Between Aug. 25 and Sept. 1, investigators from the tested nearly 3,000 Jefferson County residents for the to detect the presence of the virus in participants’ nasal swabs by the polymerase chain reaction (PCR) method and for the presence of antibodies against the virus in their blood.

The results showed that approximately 1.1% of all the participants tested positive for active coronavirus infections. Among vaccinated participants only 0.7% had an active infection, while nearly 5% of unvaccinated participants were actively infected. This number would roughly correspond to 7,260 active infections in the county, a nearly tenfold increase in infection rates over the rates measured in April, despite a sharp increase in vaccinated residents, as shown in Figure 1.

As in previous testing rounds, the team also tested for antibodies in participants. They found that independent of their vaccination status, in both the sampled and volunteer groups, nearly 16% of the participants had natural infection antibodies against the virus suggesting that they must have been infected by the virus in the recent past. These data indicate that in the last few months, at least 100,000 adults in Jefferson County have had COVID-19.

“These results highlight the steep rise in coronavirus infections in our community and provide a startling snapshot of the current state of the pandemic,” said Aruni Bhatnagar, director of the Envirome Institute. “Our estimates suggest that the number of infected individuals may be twice as high as that indicated in public records.

“Our work shows the vaccine is working as intended. Our population was almost 90% vaccinated, much higher than the 64% of fully vaccinated county residents. In the entire cohort, vaccinated people were over 12 times less likely to be infected compared with unvaccinated people. Though in our volunteer group, 65% of the active infections were in fully vaccinated individuals who had received the vaccine earlier this year. Most reported no or mild allergy-like symptoms and did not recognize that it may be a COVID infection thus did not think they needed to get tested.”

The study also provided estimates of where in Jefferson County the infections are most prevalent. To identify infection rates in different areas, the researchers classified the participants into neighborhood zones, as shown in Figure 2.

The highest rate of active infection was found in Zone 3A, or far southwestern Jefferson County. The highest rate of those recently having had an infection was found in Zone 3B, central southern Jefferson County, as shown in Figure 3.

Participants from Zone 3B also reported lower rates of vaccination, although vaccination rates were lowest in Zone 1B in western Jefferson County, as shown in Figure 4.

“Even though nearly 90% of the participants in the entire study population were vaccinated, we had areas that reported as low as 60% vaccination, and the persistence of infection in some geographical areas seems to be related to lower rates of reported vaccination,” said Rachel Keith, associate professor of environmental medicine at UofL who conducted the study. “Our results show that much work remains to be done and that knowing that rates of infection are high in their community may be an added incentive for some individuals to get vaccinated.

“Additionally, knowing that fully vaccinated individuals may still get an active infection allows those individuals to take additional precautions such as masking or testing which helps keep the community safe, including any young or immunocompromised friends and families who may need extra protection.”

“The vaccine is very effective. Nearly 96% of vaccinated individuals had detectable levels of antibodies against the virus in their blood. However, in a small number of people (less than 0.6%) the levels of antibodies were undetectable in our assay, even though these individuals were fully vaccinated,” Keith said. “The lack of a measurable response in some individuals even after vaccination may be due to their health and immune status. We are analyzing our results to find out more about why some rare individuals do not develop high antibody levels in response to vaccination.”

Using the data from more than 7,000 individuals tested over the past year, the team is trying to identify personal and environmental characteristics that increase the risk for coronavirus infection and how vaccination reduces this risk.

For this round of testing, the team collected samples at 13 locations across Jefferson County. Active coronavirus infections were analyzed by Bluewater Labs and antibodies against the virus were assayed at at the .

To randomly sample people from all parts of the city and to include proportional number of individuals of different age and race/ethnicity, researchers at UofL partnered with Westat to mail approximately 30,000 letters asking people to participate in the study. Nearly 1,000 people who responded to this invitation were tested and an additional 1,886 booked their own appointments after hearing about the study in the news or on social media.

This study was supported in part by a contract with the Centers for Disease Control and Prevention.

UofL detected the variant, a Brazilian strain known as P.1, early in April in a wastewater sample from western Jefferson County. Once researchers received the results, they alerted the Louisville Metro Department of Health and Wellness as well as the state, which confirmed a positive case in the same zip codes with different testing methods a week later.

“The ability to detect viruses early, such as in this case, gives officials more time to take precautions and contain their spread,” said Aruni Bhatnagar, professor of medicine and director of , which leads the wastewater research. “With pandemics, every second counts. In as little as one week, the virus can spread significantly, and then it becomes much harder to contain. This work gives us more time and an opportunity for targeted testing.”

UofL researchers began testing wastewater last year as part of the , a groundbreaking partnership to track COVID-19 in Louisville Metro.

The Louisville/Jefferson County Metropolitan Sewer District has sent weekly samples from 12 sites representing multiple neighborhoods and five wastewater treatment facilities that aggregate the entire county.

Those samples are taken to the , where pharmacology and toxicology assistant professor Josh Fuqua and his team process the samples and isolate viral RNA, and to the UofL Genomics and Bioinformatics Core facilities, where computer science and engineering professor Eric Rouchka analyzes the virus sequences to detect variants.

UofL recently announced the expansion of this work, backed by an . That expansion goes one step further than previous work — from identifying whether disease exists in a neighborhood to estimating how prevalent it is there.

Bhatnagar said understanding that connection could “revolutionize the way we track and contain pandemics, and not just COVID-19.”

Rather than rely solely on direct testing, such as with nasal swabs, wastewater testing can give health departments another tool to gauge the severity of community infection and to identify areas where the infection is prevalent. The tool also is faster, more efficient and less invasive.

“This is cutting-edge work – and the fact that it’s being done right here in Louisville – right here at UofL – places us at the forefront of public health innovation,” said Louisville Mayor Greg Fischer. “It shows we’re doing the work to keep our city and cities around the world safe.”

Since the beginning of the pandemic, the Co-Immunity Project has conducted ongoing testing and surveys to better understand the spread of the coronavirus and COVID-19. In the past year, UofL researchers have tested more than 12,000 people for COVID-19 infection and antibodies, beginning with frontline health care workers. They also have worked to gauge how local citizens feel about COVID-19 vaccines, with 91% of Jefferson County residents in a recent poll saying they would like to be vaccinated.

“This is one more example of how UofL has led the charge in finding new and innovative ways to detect, contain and fight COVID-19,” said Kevin Gardner, UofL’s executive vice president for research and innovation. “Developing these new, more efficient tools for tracking pandemics, such as wastewater monitoring, is a big step in advancing health for our community and beyond.”

The Co-Immunity Project needs 2,000 residents to undergo random testing for COVID-19 infection and antibodies the week of May 17-23 as part of this ongoing research. To learn more, , call 833-313-0502 or email covidsupport@louisville.edu.

UofL researchers already are testing wastewater to determine whether coronavirus infection exists in different neighborhoods around Jefferson County. This new work goes one step further, with the goal of estimating how many people within those neighborhoods are infected. If virus levels are high in the wastewater, it may be a signal of widespread infection in the community.

“This could revolutionize the way we track and contain pandemics, and not just COVID-19,” said Aruni Bhatnagar, professor of medicine. “It gives us an invaluable tool that could offer a clearer view of where and how the virus spreads.”

Researchers at UofL’s , where Bhatnagar is director, began testing wastewater last year as part of the Co-Immunity Project, a groundbreaking partnership with the to track COVID-19 in Metro Louisville.

As part of that effort, the from 12 sites representing multiple neighborhoods and five water quality treatment centers that aggregate the entire county to the UofL Center for Predictive Medicine for virus analysis.

In this new work, MSD and other community partners will continue collecting wastewater samples over the next six months. After analysis, UofL will also send the results to the CDC’s National Wastewater Surveillance System, which will help inform efforts across the U.S.

As with previous rounds of COVID-19 testing conducted through the Co-Immunity Project, researchers will recruit participants by sending letters to selected households across Jefferson County. They hope to continue to enroll a few thousand people every month and will compare their COVID-19 infection and antibody results with wastewater samples from the same area, with the goal of finding how they correlate.

“The aim of the project is to figure out whether we can estimate how many people in a given area are infected by simply testing the community wastewater,” said Ted Smith, associate professor of medicine and a lead on the wastewater epidemiology project. “Additionally, this is a passive and comparatively low-cost way to monitor community infection and has the additional benefit of being inclusive of all communities in our city and is a promising step to ensuring public health equity.”

Since the beginning of the pandemic, the Co-Immunity Project has conducted ongoing testing and surveys to better understand the spread of the coronavirus and COVID-19. In the past year, UofL researchers have tested more than 12,000 people for COVID-19 infection and antibodies, beginning with frontline health care workers. They also have worked to gauge how local citizens feel about COVID-19 vaccines, with in a recent poll saying they would like to be vaccinated.

“This is critically important work in our fight against COVID-19,” said Kevin Gardner, UofL’s executive vice president for research and innovation. “Our hope is that by working with the CDC, we can develop these new, more efficient tools for tracking pandemics and take a big step in advancing health for all of our community.”

Last year, U.S. Senator Mitch McConnell (R-KY), then-Senate majority leader, negotiated and championed five historic and completely bipartisan COVID-19 rescue packages. In addition to supporting workers and propping up the economy, these relief bills also allocated for COVID-19 testing. McConnell personally called then-U.S. Secretary of Health and Human Services Alex Azar to request that the CDC direct a portion of that funding to UofL’s Co-Immunity Project.

“Our country has responded to this terrible pandemic with innovation and discovery and Kentucky continues to play a major role in beating this virus. I’d like to congratulate Dr. Bhatnagar and UofL’s entire Co-Immunity Project on their groundbreaking study,” McConnell said in a statement. “After hearing about their work, I took this project to the highest levels of the federal government to help accelerate their research with additional federal funding.��As UPS and other Louisville employers are sending safe and effective vaccinations around the country, I’m proud top researchers right here at UofL are pushing the boundaries of knowledge in detection and prevention.”

In February, the researchers asked adults living in Jefferson County their perceptions about the coronavirus vaccine in order to identify potential barriers to vaccine uptake and to better understand vaccine hesitancy. Letters were mailed to 35,999 households across all geographic sectors of the county inviting the recipients to take part in the survey as well as to make an appointment for free testing for COVID-19, also part of the Co-Immunity Project.

“We wanted to better understand which residents had access to the vaccine as well as their attitudes toward the vaccine,” said Aruni Bhatnagar, Ph.D., director of the . “This information would help us improve equity in vaccine availability as well as help us understand the reasons behind vaccine hesitancy in our community. So, we incorporated the survey opportunity into our outreach for random community testing for the virus.”

The survey included questions about whether the person had been vaccinated, where they received most of their information about the vaccine and where they would prefer to be vaccinated. They also had an option to indicate they would not get vaccinated. They also were asked what would make them more likely to be vaccinated and what influenced those who were hesitant to vaccination.

Participants completed the questionnaire on a website that also offered them the opportunity to schedule an appointment for COVID-19 infection and antibody testing. Most of the 1,296 survey participants were age 60 or over (44%), female (61%) and white (84%) and 90.2% reported being unvaccinated.

An overwhelming majority of participants (91%) indicated they would choose to be vaccinated, with slightly lower rates among minority participants. Vaccine-hesitant participants suggested that more evidence of safety and effectiveness or their health provider’s recommendation would increase their likelihood of getting vaccinated. Although vaccines are provided for free, concerns about cost were seen in more than half the participants.

While most vaccine-hesitant participants expressed concern about side effects and safety, followed by not “tested on enough people who are like me,” minority participants expressed these concerns at higher rates and many vaccine participants from all races had concerns about the timeline of vaccine development. Other concerns were related to the efficacy of the vaccines, vaccines in general and government mistrust.

About 3% of white and 8% of minority participants indicated they would never choose vaccination. Minority participants reported they were more likely to choose vaccination with celebrity endorsement, offerings by faith organizations and vaccination requirements. White participants were more likely to choose vaccination if their family and friends or elected officials were vaccinated and with evidence of efficacy.

Most participants would prefer to be vaccinated by their health care provider, followed by a mobile or walk-in clinic, a pharmacy or a hospital. Other sites, such as community organizations, community recreation centers, workplaces or schools were of interest to one-fourth or less of participants. Minority participants were less interested in vaccination at work, pharmacies, libraries and mobile or walk-up clinics and more interested in being vaccinated at food distribution centers or by their health care provider.

Compared with white participants, minority participants were less likely to report knowing how to find out their vaccine eligibility or sign up for a vaccination.

While they acknowledge limitations to the study due to the fact that it was delivered along with the testing invitation and that it required a computer and internet access to complete, the researchers believe analysis of the results will be helpful in increasing access and acceptance of vaccines among different populations.

“Obtaining information on how to get a vaccine continues to be burdensome and solutions to this problem will help with more equitable vaccine distribution,” said Rachel Keith, Ph.D., assistant professor in the UofL Department of Medicine and a lead investigator in the Co-Immunity Project.

From December 10-14, project researchers tested 700 individuals in South Louisville for both active infection and antibodies, indicating previous infection, to develop a “snapshot” of the rates of infection in that area of the county. From those test results, the researchers estimate that as of these dates, nearly 11.16% of South Louisville residents have been exposed to the virus. Extending this estimate to all of Jefferson County would mean that nearly 73,636 individuals (1 in 10) have been infected with SARS-CoV-2 since the beginning of the pandemic.��

“The latest rates are the highest we have seen since we began testing in June and are higher than we had expected based on our previous testing drives,” said Aruni Bhatnagar, director of the UofL Christina Lee Brown Envirome Institute. “These rates show that the pandemic continues to grow at an accelerated rate. Indeed, it is likely to get worse before getting better.”

Key findings from the project’s latest round of testing:

• About 3.57% of those tested had an active coronavirus infection.
• Antibody testing indicates that the true rates of infection may be 1.6 times higher than reported in publicly available data.
• More than 28,000 Louisville residents may have been infected between November and December.
• About 73,000 people in Louisville likely have had a coronavirus infection at some point since the beginning of the pandemic, based on antibody testing.
• The highest rates of infection in December were found in people 18-to-34 years of age (10%), which was four times higher than those 35-to-59 years of age (2.6%).
• Women and men had similar rates of infection.
• Current rates of infection were much higher among non-whites (8.8%) than among whites (1.43%). To-date, nearly twice as many non-whites as whites have been infected by the virus.

The is a unique series of studies to estimate the true prevalence of SARS-CoV-2, the virus causing COVID-19, in Jefferson County. This phase of the project involves testing a representative sample of individuals from different areas in the city in proportion to the age and race of the population of the area. For this round of testing, the project researchers tested individuals living in South Louisville neighborhoods that are part of Green Heart Louisville, a separate, ongoing project to test whether increasing green space in a neighborhood improves air quality and human health.

Data released for the December tests show at least 3.57% of participants from the area were currently infected by the virus, which is nearly double the rate reported for the entire County in November (2%).

The project researchers with the , directed by Kenneth Palmer, also tested samples from the participants for antibodies against the virus and found a 1.6-fold increase in the number of individuals who previously had been exposed to the virus. Study researchers estimate that by December 14, about 73,000 individuals had been infected by the virus rather than the 48,228 known cases documented so far. These data also suggest that approximately 15,000 individuals became infected between November and December.

“Reasons for the increase in the rates of infection are not clear, but may relate to a drop in temperature,” Bhatnagar said. “From our previous work we know that . However, part of the reason may also be fewer precautions by young people and increased travel during the Thanksgiving holiday.”

Bhatnagar said he expects infection levels to continue to rise due to colder weather temperatures.

“Our models suggest that infection rates likely will continue increasing at least until the end of December and that things are likely to get much worse in the coming months as temperatures dip even further,” he said. “We are entering the most dangerous and deadly phase of the pandemic and we have to maintain high vigilance for at least the next two months until the temperatures begin to rise again or a large number of individuals are vaccinated.”

“In what may be a glimmer of hope, we have seen a consistently increasing awareness of the importance of repeated COVID-19 testing among the residents of Jefferson County, especially the South Louisville area where there was a robust push for testing and awareness by the local community members,” said Alok Amraotkar, a postdoctoral research fellow in the Envirome Institute who conducted the study. “We will keep building on these relationships with the community to curb the spread of COVID-19 virus.”

In an effort to obtain a uniform sample of residents, investigators at the Brown Envirome Institute mailed 20,000 letters to households across the study area. The invitations were sent to individuals selected using addresses derived from��U.S. Census Bureau tract boundaries. In addition, any adult resident of the area was invited to participate through news, emails and social media messages.

Nearly 1,000 individuals were tested, 700 of whom live in the Green Heart Louisville study area. The testing took place at community drive-up or walk up locations. Participants were tested both for the presence of the virus via nasal swabs, indicating current infection, and for antibodies against the virus in their blood, indicating a previous infection. Samples for the virus were tested by Bluewater Diagnostic Laboratory and antibodies were measured at UofL’s Regional Biocontainment Laboratory by the .

Wastewater monitoring results reinforce findings

The Co-Immunity Project also has been monitoring the presence of SARS-CoV-2 in Louisville wastewater in collaboration with MSD since June. During this round of community testing, daily wastewater samples were gathered from seven manhole locations within the study area. All locations revealed daily presence of the virus at levels consistent with those found across Louisville in this time period. These levels are 10 times higher than area levels just six weeks ago.

The researchers are planning to conduct a fourth round of randomized coronavirus testing in Jefferson County January 22-28.

This study was supported in part by the City of Louisville, the James Graham Brown Foundation, the Owsley Brown Family Foundation, Foundation for a Healthy Kentucky, the Jewish Heritage Fund for Excellence and others.

Between Nov. 9 and 16, researchers at the tested samples from 2,800 individuals representing all parts of Jefferson County for both active infection and antibodies, indicating previous infection. From those test results, project researchers estimate that during these dates, 1 in 50 Louisville residents were infected and that the rates of infection were nearly five times higher than the publicly reported number of cases, estimated at 0.4% of the population.

“At this rate, as many as 13,000 Louisville residents likely are infected today, many of them asymptomatic and who unwittingly may be spreading the virus,” said Aruni Bhatnagar, director of the institute. “These rates are startling and should make every person living in Louisville re-evaluate their personal precautions to avoid coronavirus, especially as we approach the holidays.”

Other key findings from the project’s latest round of testing:

• Antibody testing indicates a 150% increase in antibody presence compared to documented cases.
• Nearly 13,000 Louisville residents likely were infected between September and November.
• About 45,000 people in Louisville likely have had a coronavirus infection at some point since the beginning of the pandemic based on antibody testing.
• Shively and Northeastern Jefferson County currently show the highest rates of infection in the city.

Benefits of representative sampling

The is a series of studies to estimate the true prevalence of SARS-CoV-2, the virus causing COVID-19, in Jefferson County. This phase of the project involves testing a representative sample of individuals from different areas in the city in proportion to the age and race of the population of the area. Researchers say this approach provides a more reliable estimate of the breadth and spread of coronavirus infection in different parts of the city than testing only those who have reason to believe they may have the virus. The team tested its first community sample in June, a second in September and the most recent in November.

In addition to the 2% infection rate among randomized participants, individuals who participated without an invitation showed a 3.3% rate of infection. This is higher than the random sampling because individuals self-selecting for testing are more likely to have been exposed to the virus.

“Most of the individuals we identified as having coronavirus infection did not have overt symptoms, which indicates that a large number of cases are likely to remain undetected,” said Rachel Keith, assistant professor of environmental medicine at UofL, who conducted the study. “We do not know for sure, but it seems likely that the recent increase in infections may be in part due to asymptomatic individuals.”

The project also tested for antibodies against the virus and found a one-and-a-half-fold increase in the number of individuals who previously had been exposed to the virus. Study researchers estimate that by Nov. 20, more than 45,000 individuals had been infected by the virus, rather than the 20,500 known cases documented so far. These data also suggest that approximately 15,000 individuals became infected between September and November.

��

“One reason for the recent increase in coronavirus infection may be the recent drop in temperature,” Bhatnagar said. “ shows that low temperatures promote the spread of the virus. Hence, we were expecting the rates of infection to rise in winter, but this increase is much more than we thought.

“Unfortunately, things are likely to get much worse in the coming months as temperatures dip even further. Therefore, we urgently need collective action, maybe just for a few months more. An effective vaccine is on the horizon so it seems that there is clear hope ahead that might hearten us to make the necessary sacrifices for a little longer.”

In an effort to obtain a uniform sample of city residents, investigators at the institute mailed 30,000 letters to households across Louisville for the November round of testing. The invitations were sent to individuals selected using addresses derived from��U.S. Census Bureau tract boundaries in proportion to the total population in each geographic area.

In addition, any adult resident of Jefferson County was invited to participate through news and social media messages.

A total of 2,800 individuals were tested, 1,091 in response to the invitations and an additional 1,709 who booked their own appointments. The testing took place at 10 community drive-up or walk-up locations. Participants were tested both for the presence of the virus in participants’ nasal swabs and for antibodies against the virus in their blood, indicating a previous infection. Samples were analyzed at UofL’s Regional Biocontainment Laboratory (RBL) by assistant professor Krystal Hamorsky, and Amanda Lasnik, at the Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases.

The random sampling of different neighborhoods also allowed the team to identify areas with higher prevalence of infection. Although infections were spread throughout the county, the highest rates were in the Shively area as well as northeastern Jefferson County.

The researchers are planning to conduct a fourth round of randomized coronavirus testing in Jefferson County Dec. 9-14.

This study was supported in part by the City of Louisville, the James Graham Brown Foundation, the Owsley Brown Family Foundation, Foundation for a Healthy Kentucky and others.

The involves testing a representative sample of Jefferson County residents to discover the true prevalence of COVID-19 infection, as well as to learn how many people may have had the virus previously. Volunteers are administered a nasal swab to detect an active infection as well as a finger-stick blood test to detect antibodies to the virus, indicating a previous infection. Testing is free and no insurance is required.

In order to ensure an accurate representation of the population of the county (gender, age, race, neighborhood), invitations to participate were sent to specific households throughout Jefferson County. Individuals who received the letter are encouraged to respond according to the information in that letter. However, any resident age 18 and over who lives in Jefferson County may volunteer to participate by making an ,��or by calling 1-833-313-0502.

Testing is done at convenient drive-through or walk-up locations throughout Jefferson County. Test results are provided and there is no charge to the volunteer.

This round of testing will conclude on Nov. 15.

For testing, 1,100 health care workers collected their own blood and nasal swab samples and delivered them to researchers at . The samples were tested for both the presence of the coronavirus and antibodies against the virus, which indicate previous exposure. The samples were analyzed by the Center for Predictive Medicine for Biodefense and Emerging Infectious Disease (CPM) in (RBL), one of only 12 such NIH-funded laboratories in the nation and the only one in Kentucky.

In the new survey, the overall positivity rate for active infection was 0.45%, which is three times higher than the rate of 0.14% seen in 1,372 health care workers tested for the project in April and May.

“Although the overall number of positive cases among health care workers remains low, it has more than doubled from what we saw between April and May,” said UofL Assistant Professor in the Division of Environmental Medicine in the Department of Medicine Rachel Keith, who conducted the study. “The almost threefold increase in the number of infected individuals reflects a similar increase in the number of infections reported in Jefferson County over the same time period (100-200 cases in May to 500-700 in July).

A similar uptick was seen in the number of health care workers with antibodies against the coronavirus. About 2.2% of individuals tested positive for antibodies in this round, compared with 1% in April.

“Although we saw that the number of health care workers who tested positive for coronavirus antibody increased from May to July, it seems that coronavirus infection among health care workers has been lower than in the general population,” said Aruni Bhatnagar, director of the UofL Christina Lee Brown Envirome Institute. “In June, we conducted a random survey of 2,237 participants living across Jefferson County and found that nearly 4% of the general population had antibodies against the virus. In comparison, it appears that the number of health care workers infected by the virus may be half that of the general population.”

“The lower rates of exposure to coronavirus among our health care workers may be because they are more likely to wear masks, personal protective equipment (PPE) and maintain social distancing,” Keith said. “Many of those who tested positive work in areas that increase their exposure to coronavirus, such as emergency departments and intensive care units, although we cannot account for where they contracted the infection. For those that reported no known contact with COVID-positive patients or consistent use of PPE, it shows the impact that community transmission can have on essential workers.

“Strikingly, our male study population had 2.4% positivity and our female population had 1.6% positivity for antibodies. The sex-dependent positivity rates follow national trends,” Keith said.

Results from this round of testing also reveal what changes occur in the levels of antibodies in those who showed a positive antibody response in Round 1 testing.

“Of the individuals who tested positive for antibodies in Round 1 and who returned for testing in Round 2, 78.5% maintained a high level of SARS-CoV-2 antibodies,” said Krystal Hamorsky, assistant professor of medicine with the CPM at UofL, who conducted the antibody testing.

Kenneth Palmer, director of the CPM, added, “The high percentage of participants who retained antibodies suggests that there is little or no decline in the level of immunity acquired by those infected by the virus within three months and that any potential immunity imparted by the antibodies may be maintained at least for a few months.”

The Co-Immunity Project is a collaboration between the Louisville Healthcare CEO Council and the Christina Lee Brown Envirome Institute at the University of Louisville. The purpose of Phase I of the project is to test health care workers to identify those who have been exposed to the coronavirus and to determine how their body responds to the infection by making antibodies. If someone tests positive for antibodies to the virus, they may be able to donate plasma to help the sickest COVID-19 patients should they wish to do so.

Co-Immunity Project researchers plan a third round of testing for health care workers in October.

For , Round 2 testing begins in September of an additional 3,000 residents in different parts of Jefferson County to determine the existing prevalence of COVID-19 infection and antibodies in the general population. were announced in July.

This project has been made possible by the generous support of Christina Lee Brown, the James Graham Brown Foundation, the Jewish Heritage Fund for Excellence and many more.

Photo of health care workers wearing PPE .

From June 10-19, researchers conducting Phase II of the tested members of the Louisville community for both the presence of the novel coronavirus in the participants’ nasal passages and for antibodies against the virus in their blood. Samples were collected at five community drive-up locations across Louisville by UofL Health and researchers from the . Samples were analyzed by UofL’s Center for Predictive Medicine for Biodefense and Emerging Infectious Disease in its Regional Biocontainment Laboratory.

To obtain a representative sample for the study, households in Jefferson County were organized into geographic regions based on U.S. Census Bureau tract boundaries. Households within each region were sent invitations to participate in proportion to the population of that region. Within the regions, areas that had higher concentrations of non-white residents were sampled at a higher rate to increase their representation.

Invitations were mailed to a total of 18,232 addresses. Based on the ages and sexes of all adults in the household as provided by those responding to the invitation, one adult from each household was asked to provide a sample.

The researchers tested 509 people who responded to the mailed invitations. An additional 1,728 community members booked appointments on their own and were tested after hearing about the study in the news or on social media. Many individuals who were invited to participate did not book an appointment.��

Of the 2,237 individuals who were tested, 10% were non-white. The ages of tested individuals was as follows:

• 21% between 18-34
• 40% between 35-59
• 40% age 60 or older

Residential locations of the 2,237 participants are shown in Map 1 (below). Overall, nearly 0.4% of the population of Jefferson County was sampled.

Analysis of the study data found that at least 0.05% of the participants had an active infection during the time of the study and approximately 4% (5.1 to 3.2%) of people had detectable levels of antibodies in their blood, indicating they had been exposed to the virus earlier in the year.

“These results allow us, for the first time, to more accurately estimate the spread of coronavirus within our community. If we extrapolate the results from this study to the general population, it would suggest that as many as 20,000 people may have been exposed to the virus – many more than the 3,813 cases reported in the city by the end of June,” said Aruni Bhatnagar, director of the Brown Envirome Institute.

This difference may be due to the fact that people did not have symptoms and were not aware they were infected.

“We were told by several participants that they believed they had COVID-19 before testing was widely available. Nonetheless, our preliminary data suggest that the estimated number of people who have had COVID-19 may be 4 to 6 times higher than those who have tested positive to-date,” said Rachel Keith,assistant professor of environmental medicine at UofL who conducted the study. “This suggests that the virus is much more widespread in our community than previously estimated. I believe this indicates a need for continued and widespread testing, including antibody testing, which plays an important role in understanding the spread of disease.”

“The random sampling of the population also allows us to calculate the true mortality associated with COVID-19,” Bhatnagar said. “Previous estimates of COVID-19-related mortality have varied from 0.5 to 15%. However, given that the city had reported 209 deaths by the end of June, our results suggest that the rate of mortality associated with the virus, at least in Kentucky, may be 1.3%. This is significantly higher than the 0.65% rate suggested by the CDC. Our research suggests that many who are infected with the virus nationwide have not been tested and that there is urgent need to continue random testing so that we can calculate the most accurate mortality rate.”

The study data also provide an estimate of the spread of the infection in Louisville.

“Because participants were drawn from all parts of the city, we could estimate which areas have had the highest rates of infection,” Keith said. “Although we are still analyzing all our data, our early results show that the highest cluster of individuals exposed to the virus is in Western Louisville. (See Map 2, below). We found that the prevalence of exposure was twice as high in non-white participants as in white participants. Most (54%) of those who tested positive for the antibody were between the ages of 35-59 years old,” she said.

The researchers cautioned that because so little is known about SARS-CoV-2 and because the rates of community infection and exposure are changing rapidly, the results of this survey are applicable only to the period of June 10-19.

“Although many individuals had detectable levels, the amount of antibodies in blood varied greatly among the participants,” said Kenneth Palmer, director of the CPM. “As a result, we are not sure to what extent they are protected from re-infection. Indeed, some of our early results show that the levels of antibodies decline rapidly within a month. Therefore, we are planning to re-measure individuals who had antibodies in their blood to see if those levels are maintained over time and, if so, for how long.”

Currently, the researchers are repeating the antibody test in those health care workers who were found to have anti-SARS-CoV-2 antibodies during . They also plan to repeat community-wide testing in Jefferson County in September.

This study was supported in part by the James Graham Brown Foundation. The Co-Immunity Project is a collaboration of the UofL Christina Lee Brown Envirome Institute, the Louisville Healthcare CEO Council and three health systems in Louisville – Baptist Health, Norton Healthcare and UofL Health.

Throughout May, Phase I of the tested 1,372 health care workers at hospitals in the system. Samples were collected by UofL’s and tested at ��at the Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases.

The study found just two participants had an active infection of SARS-CoV-2, the virus that causes COVID-19. An additional 14 workers tested positive for antibodies, suggesting that they have been exposed to the virus. Unfortunately, due to low amounts of blood in some samples, antibody levels could not be tested in 128 workers.

The Co-Immunity Project, launched in April with an announcement by Kentucky Gov. Andy Beshear, is a collaboration between the and the Brown Envirome Institute. The purpose of Phase I of the project was to test health care workers at the , and UofL Health systems to identify those who have been exposed to COVID-19 and to determine how their body produced a response, or antibodies, to such infection. This information will help identify potential donors of high-quality plasma for treatment of patients with severe COVID-19 symptoms.

Interested health care workers collected their own blood and plasma samples and delivered them to researchers with the Brown Envirome Institute. The samples were then tested at the RBL, one of only 12 such NIH-funded laboratories in the nation and the only one in Kentucky. Results from Baptist Health and Norton Healthcare will be provided at a later date, but researchers say the results from workers at UofL Health facilities provide data that can be used to provide information about the pandemic and its effects.

UofL Health consists of five hospitals, four medical centers, nearly 250 physician practice locations, the UofL Health – Frazier Rehab Center and the UofL Health – James Graham Brown Cancer Center.

“The rates of infection and exposure among our health care workers is surprisingly low,” said CPM/RBL Director Kenneth Palmer, a co-investigator of the project. “Even though the number of individuals who tested positive for the antibody is more than those who had the active virus, this is still a low number, especially for those who are working in high-risk environments such as hospitals.”

“This is good news,” said UofL Assistant Professor of Medicine Rachel Keith, who conducted the study, “It shows that the precautionary measures adopted by our hospitals are working, and that patients seeking care in our hospitals are at a low risk of being infected by their health care providers.��

“These results show the need for appropriate precautions, indicating that with proper PPE and social distancing, we can minimize the threat posed by the virus to our health care community.”

Researchers advised, however, that because so little is known about the novel coronavirus SARS-CoV-2 and the disease it causes, COVID-19, much more research is necessary.

“The rates of infection among health care workers nationwide remains unknown. A recent study of health care workers in Germany who had direct contact with COVID-19 patients did find that only 1.6% tested positive for SARS-CoV-2 antibodies. This is within range of the 1% of antibody-positive health care workers our study found in Louisville,” said Brown Envirome Institute Director Aruni Bhatnagar, a co-investigator with the project.

“However, fewer individuals with antibodies against the virus also could mean that few individuals have acquired immunity, and therefore many of our health care workers may be vulnerable to the virus still lingering in our community. They may remain susceptible should infections increase again, either in the fall or some other time.”

Individuals who have recovered from COVID-19 and have antibodies against the virus are being asked by Norton Healthcare to donate plasma to help treat high-risk patients. More information is available on the .

opened earlier this month to the community to sample 2,400 participants who reside in different parts of Jefferson County to determine the existing prevalence of COVID-19 infection and immunity in the general population.

The project also will re-test health care workers across UofL Health in July to see whether the rates of infection and immunity have changed since May. The results from this second survey will be critical in monitoring how an increase in non-critical care activities in UofL hospitals has affected SARS-CoV-2 infections and see what changes occur to the levels of antibodies in those who showed a positive antibody response in Phase I testing.