Though some experts claim widespread antibody testing is key to effective public health safety, the WHO warns positive serological tests may not indicate immunity from reinfection or transmission of SARS-CoV-2

It may be the largest program of clinical laboratory testing ever conducted in the United States. Health officials are preparing to undertake large-scale serological surveys (serosurveys) to detect and track previously undetected cases of SARS-CoV-2, the novel coronavirus, that causes the COVID-19 illness.

Microbiologists, epidemiologists, and medical laboratory leaders will be interested in these studies, which are aimed at determining how many adults in the US with no confirmed history of SARS-CoV-2 infection actually possess antibodies to the coronavirus.

Serological screening testing may also enable employers to identify employees who can safely return to their job. And researchers may be able to identify communities and populations that have been most affected by the virus.

Serological Study of COVID-19 Taking Place in Five States

In an interview with Science, Michael Busch, MD, PhD, Senior Vice President, Research and Scientific Affairs of Vitalant (formerly Blood Systems), one of the nation’s oldest and largest nonprofit community blood service providers, and Director of the Vitalant Research Institute, discussed several serological studies in which he is involved. The first study, which he said is being funded by the National Institutes of Health (NIH), is taking place in six metropolitan regions in the US: Seattle, New York City, San Francisco, Los Angeles, Boston, and Minneapolis.

The interesting twist in these studies is that they will test blood samples from people donating blood. In March, participating blood centers in each region started saving 1,000 donor samples per month. Six thousand samples will be assessed monthly for a six-month period using an antibody testing algorithm that enables researchers to monitor how people develop SARS-CoV-2 antibodies over time.

Busch told Science this regional study will evolve into three “national, fully representative serosurveys of the US population using blood donors.” This particular national serosurvey will study 50,000 donations in September and December of 2020 and in November 2021.

“We’re going to be estimating overall antibody prevalence to SARS-CoV-2 within each state, but also map it down within the states to regions and metropolitan urban areas, and look at the differences,” Busch told Science, which called the serosurvey “unprecedented.”

“It’s certainly the largest serosurvey I’ve ever been involved with,” Busch said.

Serological versus PCR Testing for COVID-19

Unlike polymerase-chain-reaction (PCR)-based COVID-19 diagnostic testing, which uses nasopharyngeal swabs to detect the presence of viral RNA, serological testing such as LabCorp’s 164055 IgG test looks for the presence of SARS-CoV-2 antibodies in blood samples. A positive test indicates a previous infection.

In the third NIH serosurvey, according to Busch, NIH blood-donor serosurveys will be compared with results from population serosurveys taking place through the University of Washington and University of California San Francisco, which involve neighborhood door knocking and sampling from hematology labs.

“An antibody test is looking back into the immune system’s history with a rearview mirror,” said Matthew J. Memoli, MD (above,) an infection disease specialist with the NIH and Director of the National Institute of Allergy and Infectious Diseases (NIAID), in a news release. “By analyzing an individual’s blood, we can determine if that person has encountered SARS-CoV-2 previously.” (Photo copyright: National Institutes of Health.)

Some of the SARS-CoV-2 serological surveys underway include:

  • The National Institutes of Health serosurvey involving as many as 10,000 adults in the US who have no confirmed history of infection with SARS-CoV-2, which will analyze blood samples for two types of antibodies—anti-SARS-CoV-2 protein IgG and IgM. Researchers also may perform additional tests to evaluate volunteers’ immune responses to the virus.
  • A World Health Organization (WHO) coordinated follow-up study to its Solidarity Trial named Solidarity 2, which will “pool data from research groups in different countries to compare rates of infection,” which WHO officials say is ‘critical’ to understanding the true extent of the pandemic and to inform policy, Research Professionals News reported.
  • In Germany, the Robert Koch Institute, the country’s disease control and prevention agency, is tackling Europe’s first large-scale COVID-19 antibody testing. Its three-phase study will include serological testing on blood from donation centers, followed by testing on blood samples from coronavirus regional hotspots and then the country’s broader population.

But Can Serological Testing Prove Immunity to COVID-19?

Dark Daily previously reported on the critical role serology testing played in Singapore to help officials use contact tracing to identify people involved in COVID-19 outbreaks. (See, “Asian Cities, Countries Stand Out in the World’s Fight Against COVID-19, US Clinical Laboratory Testing in the Spotlight,” March 30, 2020.)

However, whether having COVID-19 antibodies will make people immune to reinfection or unable to spread the disease is not yet known.

“We don’t have nearly the immunological or biological data at this point to say that if someone has a strong enough immune response that they are protected from symptoms, … that they cannot be transmitters,” Michael Mina, MD, PhD, Assistant Professor of Epidemiology at Harvard’s T.H. Chan School of Public Health and Associate Medical Director in Clinical Microbiology (molecular diagnostics) in the Department of Pathology at Brigham and Women’s Hospital, told STAT.

The Times of Sweden reported the WHO warned in mid-April that there is no proof recovering from COVID-19 provides immunity.

“There are a lot of countries that are suggesting using rapid diagnostic serological tests to be able to capture what they think will be a measure of immunity,” said Maria Van Kerkhove, PhD, the WHO’s Technical Lead for COVID-19, at a news conference in Geneva, Switzerland, the Times of Sweden reported.

“Right now, we have no evidence that the use of a serological test can show that an individual has immunity or is protected from reinfection,” she said, adding, “These antibody tests will be able to measure that level of seroprevalence—that level of antibodies—but that does not mean that somebody with antibodies [is] immune.”

In addition, the reliability and quality of some serological tests produced in China, as well as some being manufactured in the US, have come into question, the Financial Times reported.

Nevertheless, as serological testing for COVID-19 becomes more widespread, clinical laboratories should plan to play an ever-increasing role in the battle to stop a second wave of the epidemic in this country.

—Andrea Downing Peck

Related Information:

Unprecedented Nationwide Blood Studies Seek to Track U.S. Coronavirus Spread

WHO Marshalls Global Study of Coronavirus Infection

Population-based Age-stratified Seroepidemiological Investigation Protocol for COVID-19 Virus Investigation

How Many People Are Immune to the New Corona Virus? Robert Koch Institute Starts Nationwide Antibody Studies

Everything We Know About Coronavirus Immunity and Antibodies–and Plenty We Still Don’t

The WHO Warns ‘No Evidence’ of Immunity to Corona Virus for Recovered Patients

Quest for Accurate Antibody Tests in Fight Against COVID-19

Asian Cities, Countries Stand Out in the World’s Fight Against COVID-19, US Clinical Laboratory Testing in the Spotlight