Antibody-Based COVID-19 Drugs that Neutralize Original Coronavirus May Not Be Effective Against New SARS-CoV-2 Variants

Researchers have found that new variants of the SARS-CoV-2 virus can evade antibodies that work against the original form of the coronavirus that sparked the pandemic, potentially undermining the effectiveness of vaccines and antibody-based drugs now being used to prevent or treat COVID-19.

New research at Washington University School of Medicine (St. Louis, MO, USA) indicates that three new, fast-spreading variants of the virus that cause COVID-19 can evade antibodies that work against the original form of the virus that sparked the pandemic. With few exceptions, whether such antibodies were produced in response to vaccination or natural infection, or were purified antibodies intended for use as drugs, the researchers found more antibody is needed to neutralize the new variants.


The findings from laboratory-based experiments suggest that COVID-19 drugs and vaccines developed thus far may become less effective as the new variants become dominant, as experts say they inevitably will. To assess whether the new variants could evade antibodies made for the original form of the virus, the researchers tested the ability of antibodies to neutralize three virus variants in the laboratory. The researchers looked at the variants B.1.1.7 (from the U.K.), B.1.135 (South Africa) and B.1.1.248, also known as P.1 (Brazil).

The researchers tested the variants against antibodies in the blood of people who had recovered from SARS-CoV-2 infection or were vaccinated with the Pfizer vaccine. They also tested antibodies in the blood of mice, hamsters and monkeys that had been vaccinated with an experimental COVID-19 vaccine, developed at Washington University School of Medicine, that can be given through the nose. The B.1.1.7 (U.K.) variant could be neutralized with similar levels of antibodies as were needed to neutralize the original virus. But the other two variants required from 3.5 to 10 times as much antibody for neutralization. Then, they tested monoclonal antibodies: mass-produced replicas of individual antibodies that are exceptionally good at neutralizing the original virus. When the researchers tested the new viral variants against a panel of monoclonal antibodies, the results ranged from broadly effective to completely ineffective.

“We don’t exactly know what the consequences of these new variants are going to be yet,” said senior author Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine. “Antibodies are not the only measure of protection; other elements of the immune system may be able to compensate for increased resistance to antibodies. That’s going to be determined over time, epidemiologically, as we see what happens as these variants spread. Will we see reinfections? Will we see vaccines lose efficacy and drug resistance emerge? I hope not. But it’s clear that we will need to continually screen antibodies to make sure they’re still working as new variants arise and spread and potentially adjust our vaccine and antibody-treatment strategies.”

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Washington University School of Medicine