Natural immunity to coronavirus can last for years, study finds

New research released on Wednesday is expected to give comfort to covid-19 survivors worried about losing their natural immunity to the coronavirus anytime soon. The results suggest that in most people, a robust immune response to the virus lasts at least eight months – and there is good signs that it could even last for years.

The decline in immunity has raised concerns since the start of the pandemic. Related coronaviruses that cause common cold are known to often re-infect people, and scattered reports of re-infections of covid-19 have emerged in 2020. Some studies have also suggested that antibody levels against the virus may drop significantly three months.

On the other hand, immunity is a complicated mess. Antibodies aren’t the only source of immunity we get against germs like the coronavirus. And, So far at least, confirmed accounts of reinfection still seem rare. This new study, published in Science, seems to provide the most up-to-date look at how our immune responses to the virus change over time – and the verdict is largely positive.

Scientists studied the blood of 180 volunteers who had confirmed covid-19, including from samples taken more than six months after infection. Antibody levels against the virus dropped slightly after infection but remained stable after that up to eight months in most people. The virus-specific T cells also declined a little after three months, but remained stable again thereafter. Meanwhile, memory B cells, which help the immune system wake up in response to a familiar threat and create more antibodies when needed, were actually more abundant by the sixth hour.month mark than one month. This is especially encouraging, as these B cells are essential for longer-term immunity, one that lasts for years.

The results don’t directly show that our immunity to covid-19 will last absolutely eight months and more. Scientists are still trying to figure out how these immune responses in the body translate to protection in the real world. But all in all, 95% of people in the study had some level of immune memory in their antibodies, B cells., and virus T cells five to eight months after the onset of their symptoms. This indicates, the authors wrote, that “lasting immunity against the secondary disease of covid-19 is a possibility in most individuals.”

Antibodies tend to be the most important part of immunity in preventing re-infection with germs. This research and others have shown that our levels of antibodies to the coronavirus can vary widely from person to person. So this could explain why a few people got re-infected in such a short time, with some cases appearing only three months later. But as the experts have noted, the other remaining aspects of our immunity should generally protect people from more serious illnesses if they are infected second time.

That said, the current pandemic situation is still very bad, with daily cases, hospitalizations, and deaths in the United States at record-high levels. IIt will take longer to resolve other important issues, such as the duration of immunity provided by the vaccine. But in a sea of ​​bad news, there is at least some hope to be seized.