Study warns young adults still at COVID-19 risk after infection

A study on more than 3,000 young, healthy US Marines has found that a previous COVID-19 infection doesn't entirely protect young adults from reinfection from the virus. The research comes from the Mount Sinai School of Medicine, which notes that young people should still be sure to get the COVID-19 vaccine even if they've previously caught and recovered from SARS-CoV-2.

The study took place from May to November 2020 and found that out of the participants who had previously had COVID-19, 10-percent experienced reinfection. Using a variety of testing, the researchers found that the participants who experienced reinfection with the virus also had lower levels of antibodies compared to the participants who didn't experience reinfection during the study period.

In addition, the viral load in reinfected Marines was found to be around 10 times lower than in the people who were infected for the first time, meaning it was possible the reinfected individuals could still transmit the virus to other people — though, the researchers say, additional research on this aspect is necessary.

The majority of reinfections resulted in asymptomatic or mild cases of COVID-19. The results may be different for previously infected individuals who have extremely low antibody levels when the reinfection occurs. The study's senior author Stuart Sealfon, MD, said:

Despite a prior COVID-19 infection, young people can catch the virus again and may still transmit it to others. This is an important point to know and remember as vaccine rollouts continue. Young people should get the vaccine whenever possible, since vaccination is necessary to boost immune responses, prevent reinfection, and reduce transmission.