A study of more than 3,000 young U.S. Marines found that those without a history of COVID-19 were five times more likely to be infected than those previously infected, according to findings published in the journal Lancet Respiratory Medicine .
The study also found that approximately 10% of young marines who were COVID-19 survivors developed a second infection.
“However, past infections do not guarantee immunity, and vaccination remains crucial,” The Lancet said on Twitter, providing the link to the findings.
“Among 189 seropositive participants, 19 (10%) had at least one positive PCR test for SARS-CoV-2 during the 6-week follow-up (1 · 1 cases per person-year),” the study found.
The previously infected mariners who were re-infected had lower antibody levels and less neutralizing antibodies, compared to previously infected marines who were not re-infected, the study found.
“Although antibodies induced by initial infection are largely protective, they do not guarantee effective SARS-CoV-2 neutralizing activity or immunity against subsequent infection,” the study said.
“This analysis was conducted as part of the prospective COVID-19 Health Action Response for Marine Study (CHARM). CHARM included mainly male U.S. Marine recruits, ages 18-20, after a two-week quarantine without supervision at home,” it said .
A separate study published in the Lancet in March found that the majority of people who had COVID-19 were protected from getting it back for at least six months, but older people are more prone to reinfection than younger people. read more
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