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COVID Antibodies May Last Days To Years, Depending On Severity Of Infection

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  1. The Good Doctor

    The Good Doctor Golden Member

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    Antibodies against SARS-CoV-2 are likely to wane at different rates depending on the severity of the infection, new research suggests.

    "The key message from this study is that the longevity of functional neutralizing antibodies against SARS-CoV-2 can vary greatly and it is important to monitor this at an individual level," Dr. Lin-Fa Wang, with the Program in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, said in a news release.

    The researchers followed 164 COVID-19 patients for up to nine months after infection. They identified five distinct groups based on patterns of neutralizing antibodies.

    - A 'negative' group of patients who did not develop neutralizing antibodies at the 30% inhibition level. These people comprised 12% of patients in the study.

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    - A 'rapid waning' group (27%) who had varying early levels of antibodies from around 20 days after symptom onset, but sero-reverted in less than 180 days.

    - A 'slow waning' group (29%) who remained mostly antibody-positive at 180 days post-symptom onset.

    - A 'persistent' group (32%) who showed little change in their antibody levels up to 180 days.

    - A 'delayed response' group (2%) who showed a marked rise in neutralizing antibodies during late convalescence (at 90 r 180 days after symptoms appeared).

    In their Lancet Microbe paper, the researchers note that persistence of neutralizing antibodies was associated with disease severity and sustained levels of pro-inflammatory cytokines, chemokines, and growth factors. However, T-cell responses showed "no clear correlation" with the different patterns of neutralizing antibody dynamics. T-cell responses were similar among the different groups.

    Based on the different decay dynamics, the researchers developed an algorithm that predicted a "wide range of neutralizing antibody longevity, varying from around 40 days to many decades," which has implications for vaccination.

    "The rate of waning suggests reinfection during second and later waves of infection is likely to occur, limiting the viability of a herd immunity strategy before an effective vaccine. Assuming similar rates of waning after vaccination, annual administration is likely to be necessary to prevent large outbreaks as population immunity declines," they note in their article. On the other hand, neutralizing antibodies might persist for many years in some patients who have recovered from COVID-19.

    "This work may have implications for immunity longevity after vaccination, which will be part of our follow-up studies," Dr. Wang added in the news release.

    Funding for this research was provided by the National Medical Research Council, Biomedical Research Council, and A*STAR, Singapore. Dr. Wang is a co-inventor on a patent application for the surrogate virus neutralization test technology and a commercial kit being marketed by GenScript Biotech.

    —Reuters Staff

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