U.S. Marines Study Finds Getting COVID Won't Protect Young People From Reinfection

FRIDAY, April 16, 2021 (HealthDay News) -- Young adults, take note: A new study finds that even if you have suffered a bout of COVID-19, it is not a guarantee against a second infection.

Researchers said the results show that even those young people who've been struck by the new coronavirus still need to be vaccinated against it.

The study was conducted between May and November 2020 and included more than 2,300 healthy U.S. Marines, aged 18-20.

During that time, about 10% of those who were previously infected with SARS-CoV-2 became reinfected, while infections were reported in 50% of those not previously infected.

Although the study looked at young, fit, mostly male Marines in crowded conditions, the findings likely apply to many young people, according to the study published April 15 in The Lancet Respiratory Medicine journal.

Despite previous infection and the presence of antibodies, young people still need to get vaccinated to boost their immune responses, prevent reinfection and reduce transmission, the researchers urged.

"As vaccine rollouts continue to gain momentum it is important to remember that, despite a prior COVID-19 infection, young people can catch the virus again and may still transmit it to others. Immunity is not guaranteed by past infection, and vaccinations that provide additional protection are still needed for those who have had COVID-19," senior study author Dr. Stuart Sealfon said in a journal news release. He's a professor of neurology at the Icahn School of Medicine at Mount Sinai in New York City.

Fortunately, a recent survey has shown that most young Americans are in favor of being vaccinated. University of Michigan researchers reported that 76% of U.S. teens and young adults were willing to get the COVID-19 vaccine in October 2020. A repeat survey in late March 2021 showed that the number of young people in favor of the vaccine had risen by then to 84%.

One expert not connected to the research said young people should heed the study's warning.

"The takeaway for everyone, but especially younger persons, is that immunity from natural infection with COVID-19 is not guaranteed," said Dr. Robert Glatter, an emergency room doctor at Lenox Hill Hospital in New York City.

"Individuals should still be vaccinated, even if you had COVID-19 and then recovered. While the risk of reinfection is low, and may likely result in asymptomatic infection, there is still a small chance that you could develop a more severe illness, and continue to transmit the infection to others," he noted.

"While natural infection provides immunity to all regions of the virus, the vaccine targets the spike protein, the key region where the virus attaches to the cells in your body," Glatter explained. "By targeting the spike protein, vaccination provides a higher degree of specific antibody protection, unlike the general antibody response from COVID-19 infection."

In the study, the researchers found that neutralizing immune system antibodies were less common among the participants who were previously infected (32%) than those who weren't reinfected (83%).

"Our study shows that some individuals with lower levels of neutralizing antibodies were reinfected, indicating that it is possible that previously infected and recovered people are susceptible to new SARS-CoV-2 infection at a later time. These reinfections may be asymptomatic, as observed in the majority of our participants," said co-author Lt. Dawn Weir, from the Navy Medical Research Center.

"The takeaway message for all young people, including our military service members, is clear -- immunity resulting from natural infection is not guaranteed; you still need to be vaccinated even if you have had COVID-19 and recovered," Weir said in the release.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 reinfection.

SOURCES: Robert Glatter, MD, emergency room doctor, Lenox Hill Hospital, New York City;The Lancet Respiratory Medicine, news release, April 15, 2021