Antibodies may drop, but immunity remains in survivors: Covid-19

Even though Covid survivors may have low antibodies, they will have immunity against reinfection

Corona Virus

LUCKNOW: After a few international researchers found a significant decline in antibodies in Covid-19 patients after recovery, King George’s Medical University (KGMU) has also found evidence to support the findings.

KGMU’s transfusion medicine department, which has been collecting plasma from Covid patients after recovery, has found that in at least two plasma donations, antibodies dropped down by 75% in less than three months. A team, led by the head of KGMU’s transfusion medicine department Prof Tulika Chandra, has found 25% of plasma donors had negative antibodies which means they did not have any antibody against the virus, but tested negative after hospitalised treatment.

“We have had 18 plasma donations till Tuesday. In two cases, we took plasma again after over two months from the time of infection. We found a significant decline in antibodies. The two plasma units had just 25% antibodies left,” Prof Chandra told TOI. She, however, clarified that decrease in antibodies did not mean that immunity was lost too.

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“In case of Covid, no reinfection has been reported in any part of the world. Possibly, once antibodies against coronavirus develop in the body, memory cells in our bodies are sensitised and they get activated against the virus if it tries to enter the body again,” she said. She gave the example of chickenpox in which, once infected, a patient develops lifelong immunity against it. “In testing, you don’t find antibodies against chickenpox in a person. Every virus behaves differently and there is still much that we need to know about coronavirus,” she added.

“Even though Covid survivors may have low antibodies, they will have immunity against reinfection and their plasma would still save another patient’s life,” Prof Chandra said.

“We have also had plasma donors who had negative antibodies. This could mean that they were either false positive cases as no test can give 100% confirmation, or that they had the virus but were asymptomatic and traced through contact testing. After treatment, they would have tested negative in just a couple of days. We are still learning about the virus,” she said. “More patients should come forward to donate plasma after recovery to save lives of other patients. Their immunity will not get affected by donation,” said Prof Chandra.

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