Adaptive Immune System Against COVID-19 Can Last For At Leas
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New data suggest that nearly all COVID-19 survivors have the immune cells necessary to fight re-infection. The findings, based on analysis of blood samples from 188 COVID-19 patients, suggest that responses, SARS-CoV-2, from all major players in the adaptive immune system, which learns to fight specific pathogens, can last for at least eight months after the onset of symptoms from the initial infection.

The new study helps clarify some concerning COVID-19 data from other labs, which showed a dramatic drop-off of COVID-fighting antibodies in the months following infection. Some feared that this decline in antibodies meant that the body wouldn't be equipped to defend itself against reinfection.

The researchers found that virus-specific antibodies do persist in the bloodstream months after infection. Importantly the body also has immune cells called memory B cells at the ready. If a person encounters SARS-CoV-2 again, these memory B cells could reactivate and produce SARS-CoV-2 antibodies to fight re-infection. They found that spike-specific memory B cells actually increased in the blood six months after infection.

COVID-19 survivors also had an army of T cells ready to fight reinfection. Memory CD4+ helper T cells lingered, ready to trigger an immune response if they saw SARS-CoV-2 again. Many memory CB8+ killer T cells also remained, ready to destroy infected cells and halt a reinfection.

The different parts of the adaptive immune system work together, so seeing COVID-fighting antibodies, memory B cells, memory CD4+ T cells and memory CD8+ T cells in the blood more than eight months following infection is a good sign.

The team cautions that protective immunity does vary dramatically from person to person. In fact, the researchers saw a 100-fold range in the magnitude of immune memory. People with a weak immune memory may be vulnerable to a case of recurrent COVID-19 in the future, or they may be more likely to infect others.

Source:
https://science.sciencemag.org/content/early/2021/01/05/science.abf4063
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