Researchers Seek to Pin Down Whether COVID-19 Antibodies Fade Quickly or Last Months

Although a recent study found that coronavirus disease 2019 (COVID-19) antibodies can last between 5 and 7 months after recovery, contradictory research suggests that they fade within weeks. The different findings come as investigators seek to understand whether plasma treatments are effective in patients with COVID-19.

Study Finds Long-Term Antibodies

In a study conducted at the University of Arizona, investigators found high-quality antibodies in patients between 5 and 7 months after their recovery, suggesting that the antibodies are effective and long-lasting.¹

According to the study investigators, when the virus first infects cells, the immune system deploys plasma cells that produce antibodies to fight the virus. According to a press release by the study authors, those antibodies appear in blood tests within 14 days of infection. The second stage of the immune response involves the creation of long-lived plasma cells, which produce high-quality antibodies that provide lasting immunity.¹

To investigate how long these antibodies survive, investigators tracked antibody levels over several months in patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. They found that the virus’s specific antibodies are present in blood tests at viable levels for at least several months, although they believe immunity lasts significantly longer.¹

“We clearly see high-quality antibodies still being produced 5 to 7 months after SARS-CoV-2 infection,” said investigator Deepta Bhattacharya, PhD, in a press release. “Many concerns have been expressed about immunity against COVID-19 not lasting. We used this study to investigate that question and found immunity is stable for at least 5 months.”¹

According to the press release, earlier studies have extrapolated antibody production from initial infections and suggested that antibody levels drop quickly after infection, with only short-term immunity. Bhattacharya said these conclusions focused on short-lived plasma cells and did not take into account the long-lived plasma cells and the high-quality antibodies that they produce.¹

For their research, the investigators first created a blood test to detect the SARS-CoV-2 antibodies. They partnered with the state to test 5882 volunteers beginning April 30, with the testing efforts later expanded statewide. Notably, the investigators said most tests only analyze the S1 region of the SARS-CoV-2 virus. Their test also analyzed the S2 region, and antibodies must be present in both locations for the test to be declared positive.¹

“When we began, the first test we developed was 99% accurate for measuring antibodies in 1 part of the virus,” said researcher Janko Nikolich-Zugich, MD, PhD, in the press release. “We decided to confirm, and hopefully improve, that accuracy level by looking at another part of the virus that makes antibodies independent of the first location. We then validated that test, knowing some people will make antibodies more consistently for 1 part of the virus than the other. We put the 2 tests together, and only people who show antibody production for both parts of the test are determined to be positive.”¹

According to the press release, the test has an extremely high positivity rate. Of 5882 tests completed and analyzed in the published paper, only 1 has returned a false positive, a rate of less than .02%. Nikolich-Zugich said the team has now tested nearly 30,000 people, and antibody tests are still available for patients 18 years of age and older at multiple locations throughout Arizona.¹

Research Suggest Antibodies Fade Quickly

Contradicting the research at the University of Arizona, a study published in mBio found that the ability of plasma to neutralize the COVID-19 virus decreased significantly soon after symptom onset. In a press release, the investigators said understanding how long antibodies last is essential to understanding whether plasma treatments are effective and for how long.²

If convalescent plasma is shown to have a benefit, the researchers said it might need to be collected during a specific window of time after the patients’ recovery. However, they noted that recovery patients cannot donate blood until at least 14 days after their symptoms have subsided.²

“We don’t want to transfuse the virus, just transfuse the antibodies,” said investigator Andre Finzi, PhD, in a statement. “But at the same time, our work shows that the capacity of the plasma to neutralize viral particles is going down during those first weeks.”²

According to the press release, previous studies have found that antibodies against the SARS-CoV-2 spike protein peak between 2 and 3 weeks after the onset of symptoms. An earlier cross-sectional study conducted by Finzi et al found that the ability of plasma to neutralize the virus decreased between 3 and 6 weeks after symptom onset.²

In the new study, the team analyzed blood samples collected at 1-month intervals from 31 individuals recovering from COVID-19. They analyzed the levels of immunoglobulins that act against the coronavirus S protein and tested the ability of the antibodies to neutralize the virus.²

Through this research, they observed variations in the levels of individual patients but identified consistent levels of immunoglobulins G, A, and M, which target the binding site. These immunoglobulin levels all decreased between 6 and 10 weeks after symptom onset, during the same period in which the efficacy of the antibodies decreased.²

The group has continued studying blood samples from the patients in order to understand how the levels of antibodies change over time. In the press release, Finzi said this is critical both for optimizing the use of convalescent plasma and for understanding vaccine efficacy.²

REFERENCE

• UArizona Health Sciences Study Shows SARS-CoV-2 Antibodies Provide Lasting Immunity [news release]. University of Arizona; October 12, 2020. https://opa.uahs.arizona.edu/newsroom/news/2020/uarizona-health-sciences-study-shows-sars-cov-2-antibodies-provide-lasting. Accessed October 21, 2020.
• In recovering COVID-19 patients, antibodies fade quickly [news release]. EurekAlert!; October 16, 2020. https://www.eurekalert.org/pub_releases/2020-10/asfm-irc101520.php. Accessed October 22, 2020.