COVID-19: younger patients develop fewer neutralising antibodies, study finds
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But older patients who had more neutralising antibodies did not recover faster
- Analysis of blood samples from 175 patients with mild COVID-19 disease, revealed that about 30% of patients had unexpectedly low levels of antibodies against novel coronavirus (SARS-CoV-2). Ten patients had such low levels of neutralising antibodies that these could not be detected, while two patients showed very high levels.
- The study threw up another surprise — the plasma of elderly and middle-age patients had significantly higher amount of neutralising antibodies and spike-binding antibodies than young patients.
- Though about 30% of patients failed to develop high amounts of neutralising antibodies even after recovering from COVID-19 disease, the disease duration was not longer than older patients. Likewise, older patients who had more neutralising antibodies did not recover faster.
- So immaterial of the amount of neutralising antibodies found, both young and old patients took the same time to recover.
- The research was not able to detect viral DNA in the blood samples collected, and information about viral load was not available for all the patients. So it is not known if the young patients had lower viral load thus resulting in lower amount of neutralising antibodies, hence ‘This study is preliminary’.
- The efficacy of passive antibody therapy, otherwise called as convalescent plasma therapy, relies on the concentration of neutralising antibodies in the plasma.
- The low levels of neutralising antibodies in younger patients who have recovered from the disease strongly suggest that convalescent plasma should be titrated before being used for therapy.
- The low levels of neutralising antibodies in about 30% of patients would put them at risk of infection rebound or reinfection and suggest that further studies are undertaken to understand this.
- The higher amounts of neutralising antibodies found in older patients may be due to “strong immune response” in aged people, the study suggests. But whether the elevated neutralising antibodies found in older people protect them from progression to severe and critical conditions is not known.
- Antibodies generated in response to novel coronavirus (SARS-CoV-2) could bind with 2003 SARS strains. However, the binding was not able to stop the SARS virus from replicating. This raises the possibility of developing a vaccine that might be effective against both novel coronavirus and the 2003 SARS virus.