Trending Clinical Topic: Antibodies

Ryan Syrek


July 10, 2020

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As the coronavirus pandemic rages on, issues surrounding the antibodies developed after infection became this week's top trending clinical topic. The protection conferred by antibodies is currently under investigation, and early reports show reasons for concern. A study from China found that people who develop antibodies after becoming infected with SARS-CoV-2 may not retain them for more than a few months. This is especially true for individuals with asymptomatic infection (see Infographic below).

A separate study of patients from New York found that, although the majority of those studied did produce antibodies after coronavirus infection, 33% of individuals tested had antibody titers that implied having no immunity to repeat infection. Those who were hospitalized for COVID-19 were more likely to have neutralizing antibodies, which suggests that those with more severe illness are more likely to be immune in the future. Although the lack of high levels of neutralizing antibodies is a concern, experts suggest that those infected a second time are not likely to have as severe an infection as their first.

Testing used to identify antibodies has also been a hot topic. In England, clinical academics and physicians expressed concerns over the rollout of COVID-19 antibody testing. The experts argue that large-scale testing is not yet clinically warranted and that the test performance has not been adequately assessed. Although hailed as a "game changer" by Prime Minister Boris Johnson, 14 experts authored a letter in BMJ that expressed doubts about the usefulness of the current approach.

Antibody testing may also play a role in assessing whether COVID-19 has invaded the brain. A small case series of three patients in a US hospital who had COVID-19 and encephalitis found that although only one had abnormal white blood cell or protein levels present in CSF, all had evidence of immunoglobulin (IgM) antibodies. Lead author Karima Benameur, MD, says the findings suggest that CSF test results that indicate normal levels of inflammatory proteins do not necessarily mean that the virus has not entered the brain. She recommends CSF IgM testing, if possible, to confirm brain involvement in these patients.

Researchers are also looking into whether antibody therapy may be a viable prevention strategy against COVID-19. Although vaccines are under development, some experts believe that antibody therapy may serve as a bridge until they are available. A team led by the company Regeneron has screened thousands of human antibodies against SARS-CoV-2 and were able to create a cocktail of two antibodies that decreased the chances of resistance against infection. That cocktail is now being investigated in humans. Scientists from the Scripps Research Institute found a "super antibody" that was able to protect hamsters dosed with the virus from getting sick. Several other groups have also made progress in identifying potentially protective antibodies.

With the World Health Organization suggesting that the worst phase of the pandemic may be yet to come, antibodies are likely to remain an incredibly important focus, as they were this week.

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