Coronavirus immunity could last decades for some people – but only days for others

The duration of immunity to coronaviruses after being infected can vary widely from person to person, suggests a new study.

Researchers found that some people who had neutralizing antibodies against COVID-19 antibodies saw levels decrease after just a few days or even weeks.

But at least a third of the participants had no level changes after at least six months, and some even saw the levels rise, suggesting their immunity could last for decades.

At least 10 percent never even had detectable levels.

The team, from Duke-NUS Medical School in Singapore, said the results prove that some previously infected patients are more likely than others to be re-infected in subsequent waves, or even with highly contagious variants.

“ The key message from this study is that the longevity of functional neutralizing antibodies against SARS-CoV-2 can vary widely and it is important to monitor this at the individual level, ” said corresponding author Dr Wang Linfa. , director of the emerging program. Infectious Diseases at Duke-NUS Medical School.

“This work may have implications for the longevity of immunity after vaccination, which will be part of our follow-up studies.”

For the study, published in The Lancet Microbe, the team examined 164 COVID-19 patients in Singapore for six to nine months.

The patients each donated blood samples, which the researchers analyzed for neutralizing antibodies and for T cells, which are a type of white blood cell that binds to and kills viruses.

The data was then used to help create an algorithm to predict the trajectories of neutralizing antibodies over time.

Participants were classified into five groups based on the lifespan of their antibodies against COVID-19.

The first group, called the “negative” group, never had detectable neutralizing antibodies and made up about 11.6% of patients.

The next group, the “rapidly decreasing” group, made up 26.6% of patients and had variable antibody levels early on that declined rapidly within days.

Then the “ slowly decreasing ” group had antibodies that faded within six months, accounting for 29% of the participants.

The so-called “persistent” group, comprising 31.7 percent of the participants, showed little change in their antibody levels for at least six months.

Finally, the delayed response group, 1.8% of patients, showed an increase in neutralizing antibodies during the study period.

However, the study found that most of the patients had elevated levels of T cells, even among those in the “negative” group.

This implies that individuals can still be protected if they have a strong T cell response despite low levels of neutralizing antibodies.

“Our study examines neutralizing antibodies that are important for protection against COVID-19. We have found that antibodies to SARS-CoV-2 decrease in different people at different rates, ”said corresponding author Dr David Lye, director of the National Center for Infectious Diseases in Singapore.

“This underscores the importance of public health and social measures in the ongoing response to a pandemic epidemic.

“However, the presence of T cell immunity offers hope for longer term protection which will require more studies and time for epidemiological and clinical evidence to be confirmed.”