Scientists do not know for sure yet, but they believe that it is unlikely that a person can contract coronavirus twice.

Health experts believe that those with COVID-19 will have some form of immunity to a second infection. But they don’t know how much protection is or how long it will last.

There have been reports of people testing positive for the virus weeks after they were believed to have recovered, leading some to believe they had been infected a second time. The most likely hypothesis, according to experts, is that they suffered from the same disease or that tests detected remnants of the original infection. In addition, it is possible that the tests yielded false positives.

Scientists say there have been no documented samples of a patient spreading the virus to others after testing positive again.

With similar viruses, studies have shown that people can become infected again between three months and a year after the first infection. At the moment it is too early to know if this is also a possibility with coronavirus.

“It’s a very emerging science,” said Philip Landrigan, director of Boston College’s global public health program.

A small US study published last week also found that antibodies to the coronavirus could last as little as a few months in people who had mild symptoms of COVID-19, suggesting they could get it again. But antibodies are not the only defense against a virus, and other parts of the immune system may help provide protection.

Settling the question of whether reinfection is a possibility is important. If it can happen, it could undermine the idea of ​”immunity passports” to return to the workplace. And it would not bode well for hopes of a lasting vaccine.