Local doctor says COVID-19 herd immunity 'may not be necessarily attainable'

A Los Angeles-based doctor discussed with Eyewitness News on Thursday morning what scientists are learning about immune response to coronavirus.
LOS ANGELES (KABC) -- A Los Angeles-based doctor discussed with Eyewitness News on Thursday morning what scientists are learning about immune response to coronavirus.

The study, published in the peer-reviewed New England Journal of Medicine, is the first to carefully estimate the rate at which the antibodies against SARS-CoV-2 disappear, according to researchers.

Researchers analyzed antibody test results from 20 women and 14 men ranging in age from 21 to 68, including four who hadn't been tested for COVID-19 but had symptoms compatible with coronavirus and had cohabitated with people who were known to have the virus. Most had been mildly ill.

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Antibody tests were conducted of patients' blood samples at an average of 36 days and 82 days after their initial symptoms of infection.

The research showed people with mild cases of COVID-19 had antibodies that dropped sharply over the first three months. Additionally, those antibodies continued to rapidly decrease after that time period.

Dr. Anu Seshadri, with the Primary Care and Pediatrics division at UCLA Health, said although more research is needed, the findings raise some concerns about aspects of immunity.

"Immunity may not be as long lasting in those that are affected with mild illness. Mild illness (comprises a) majority of the people that are infected with COVID-19, so people may not have the so-called immunity passports that we're talking about," she said.

Dr. Seshadri added that herd immunity, which is a resistance to the spread of the disease within a population due to a majority of the people being immunized, "may not be necessarily attainable."

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The study also raises concerns about "vaccine durability," which may be difficult to achieve, according to Dr. Seshadri.

The research, conducted over a 90-day period, looked at a specific Memory-B cell - IgG. The role of T-cells -- another marker or immunity -- may also need to be analyzed, Dr. Seshadri.

"Every day we're just gathering more and more information, seeing if it's reliable and using that," she said.

City News Service contributed to this report.
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