While the Centers for Disease Control and Prevention has launched a strategy to use antibody testing for studies that study the spread of the virus in various locations and populations, the federal government has not coordinated an effort to track raw data from antibody tests conducted in all states.
Antibody tests can be used to detect whether people have previously been exposed to coronavirus and developed antibodies to it, although it is still unclear whether the presence of antibodies means that someone is immune to the virus.
The current estimate of people who have been infected with coronavirus in the United States – $ 1.25 million, according to Johns Hopkins University figures – is almost certainly a subset, said Dr. Peter Hotez, professor and dean of the National School of Tropical Medicine at Baylor College of Medicine.
"The problem is we don't know if the real number is 10 times more or 20 times more, and by having extensive antibody testing that will give us a better idea," Hotez said.
Yet, of 41 states that responded to an inquiry from CNN, only 22 states said they were currently tracking or collecting data on antibody testing in any way. Some of these states, including New York, Louisiana and California, now require laboratories to report antibody test results, while others have launched limited studies to study antibody incidence.
To further complicate matters, some state health departments have expressed concern about the reliability of available antibody samples, many of which originally came on the market without reviewing the Food and Drug Administration.
States concerned with the accuracy of antibody testing
Data on antibody tests "are of questionable reliability; we do not track or analyze them," said an Oregon Health Authority spokesman.
A Vermont working group researching antibody tests for the state's health commissioner "found that currently available tests are not accurate or reliable enough to make decisions or recommendations to change behavior at the individual or population level," according to a Vermont health operations spokesman.
A spokesman for the CDC said the agency has no estimates of how many antibody tests have been performed or information on all the results of these tests. But the spokesman also said that CDC is working with states that conduct antibody testing as well as some commercial companies to get test results.
On Monday, the FDA changed its policy to require commercial antibody testing manufacturers to submit emergency use permit requests, or EUA, and validation data within ten business days.
Despite criticizing the agency's original policy, an FDA spokesman told CNN, "Without the more flexible policy, we would not be so far in our ability to use antibody testing. Now that the FDA has authorized multiple tests and the National Cancer Institute, in collaboration with us and others, conducting antibody test evaluations, we may and have changed our policy to require that all commercial manufacturer tests be FDA-authorized to remain or enter the US market. "
The FDA spokesman added that the agency has ongoing talks with states to provide technical assistance.
Progress has been uneven
Still, some state health officials say the current use of antibody tests is limited.
Massachusetts State Epidemiologist Dr. Catherine Brown told CNN that the state's health department has begun receiving results from tests that detect antibodies, but she said the numbers are small and not geographically distributed enough to draw conclusions about infection rates.
Aside from questions about the accuracy of tests that have not been FDA-approved, she said the link between the presence of antibodies and the individual's immunity to the disease remains unclear. The World Health Organization has said: "There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected against a new infection."
Brown also said there is limited knowledge about the timing and duration of different types of antibodies compared to when someone was infected.
"At the moment, without using serological tests to determine how many people in a society were exposed to the virus, it should be used sparingly and with a solid understanding of its limitations," Brown said.
Experts warn against drawing conclusions from released data
Some states have published data on antibody testing.
Other states, including Alabama, Idaho and Utah, told CNN that they are receiving results or information from antibody tests, but have not yet implemented processes to analyze the data.
Kelly Wroblewski, director of Infectious Diseases for the Association of Public Health Laboratories, which represents state and local public health laboratories, told CNN that she has heard from epidemiologists in states that are currently collecting such data from various laboratories that have lost track of what the data does because of the different quality of different tests.
"You won't necessarily get reliable dissemination data if you only collect from the labs that can use good or bad tests," Wroblewski said.
To clarify the situation, Wroblewski's organization APHL and the Council of State and Territorial Epidemiologists on Thursday issued a guidance paper on antibody testing.
The document says researchers need more data on test performance and human immune response to coronavirus for antibody testing methods to be used effectively, but also says public health officials can use antibody tests to conduct surveys to estimate the prevalence of previous infection. Another potential application listed is to identify individuals with antibodies to serve as plasma donors for patients with coronavirus.
Rhode Island Governor Gina Raimondo announced Wednesday that 5,000 residents of her state will be selected at random to receive tests that can diagnose the virus as well as antibody tests for Covid-19 so that the state can have a more accurate portrait of how many people have been exposed for the virus.
New York City, in collaboration with the Department of Health and Human Services and the CDC, will offer antibody testing for 140,000 health workers and first responders starting next week, Mayor Bill de Blasio said Tuesday.
Trumps & # 39; Testing Blueprint & # 39; leaving states on their own
Heather Pierce, senior director of science policy and regulatory advisor in the Association of American Medical Colleges, said she is not surprised that states have developed different approaches to antibody testing.
"States have been told to make their own plans, and there are no strict guidelines for testing at all, let alone serology tests," Pierce said.
Pierce said states should recognize the limitations of antibody testing, but start building databases that track antibody test results and types of tests used, so that as more information becomes available about the relationship between coronavirus antibodies and immunity, states will have the data clear.
"It is to make sure that states collect the information that will eventually be useful," said Pierce, who added that states should ideally use "the same vocabulary" in the datasets so they can be compared.
Caroline Buckee, associate professor of epidemiology at Harvard T.H. Chan School of Public Health, said knowing more about who has had the virus will reveal more about "where we are on the epidemic curve."
"And it has very important implications for politics, like whether we should go back to work and whether we will reopen schools," Buckee said.