Although antibodies induced by SARS-CoV-2 infection are largely protective, they do not completely protect against reinfection in young people, as evidenced through a longitudinal, prospective study of more than 3,000 young, healthy members of the US Marines Corps conducted by researchers at the Icahn School of Medicine at Mount Sinai and the Naval Medical Research Center, published April 15 in The Lancet Respiratory Medicine.
“Our findings indicate that reinfection by SARS-CoV-2 in health young adults is common” says Stuart Sealfon, MD, the Sara B. and Seth M. Glickenhaus Professor of Neurology at the Icahn School of Medicine at Mount Sinai and senior author of the paper. “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.”
The study, conducted between May and November 2020, revealed that around 10 percent (19 out of 189) of participants who were previously infected with SARS-CoV-s (seropositive) became reinfected, compared with new infections in 50 percent (1.079 out of 2,247) of participants who had not been previously infected (seronegative). While seronegative study participants had a five times greater risk of infection than seropositive participants, the study showed that seropositive people are still at risk of reinfection.