Past Covid infections do not completely protect people from reinfection: studies

The results of a new study led by researchers at Mount Sinai School of Medicine suggest that vaccination against Covid-19 remains important, even in previously infected young adults.

Antibodies induced by SARS-CoV-2 infection are largely defensive, but young people, as evidenced by a longitudinal prospective study of more than 3,000 young and healthy members of the US Marine Corps. It does not completely protect against reinfection. Ikarn Medical University and Naval Medical Research Center on Mount Sinai.

The findings were published in the journal The Lancet Respiratory Medicine.

“Our findings show that reinfection with SARS-CoV-2 is common in healthy young adults,” said Stuart Sirphon, MD, MD, Sara B. and Seth, Mount Sinai School of Medicine. M. Grickenhaus, Ph.D. in Neurology and Senior Author, said. paper.

“Despite the previous Covid-19 infection, young people can catch the virus again and infect others. This is an important point to know as the vaccine continues to roll out. Young people should be vaccinated as much as possible because they need to be vaccinated, to boost their immune response, prevent reinfection and reduce infection. “

In this study, conducted between May and November 2020, about 10% (19 of 189) of participants previously infected with SARS-CoV-s (seropositive) were re-infected. On the other hand, it became clear that 50% (1.079) were newly infected. Of 2,247 participants who have never been infected (seronegative).

Participants in the seronegative study were five times more at risk of infection than those with seropositive, but this study showed that seropositive people were still at risk of reinfection.

The study population consisted primarily of 3,249 male Marines aged 18 to 20 years, and upon arriving at a two-week quarantine supervised by the Marines before entering basic training, the baseline SARS-CoV-2 IgG Serum positive (as defined as a 1: 150 or greater dilution with a defined receptor binding domain and a full-length peplomer enzyme-binding immunoadsorbent) [ELISA] Assay. ).

The presence of SARS-CoV-2 was assessed by PCR at the beginning, middle, and end of quarantine. After appropriate exclusion, including PCR-positive participants during quarantine, the research team conducted three biweekly PCR tests in both the seronegative and seropositive groups as recruits left the quarantine for basic training. It was conducted.

During the study, new recruits who were positive for a second COVID-19 infection were quarantined and the research team conducted additional tests. Neutralizing antibody levels were also obtained from subsequently infected sero-positive and selected sero-positive participants who were not re-infected during the study period.

Of the 2,346 Marines followed for sufficient time to analyze this reinfection rate, 189 were seropositive and 2,247 were seronegative at the start of the study. Overall, both groups of new employees were 1,098 (45% new infections during the study. Of the seropositive participants, 19 (10% were positive for the second infection during the study. Spondyloarthresis). Of the recruits who were, 1,079 (48 cents) were infected during the study.

To understand why these reinfections occurred, the authors studied the antibody response between reinfected and uninfected participants. They found that in the seropositive group, reinfected participants had lower antibody levels against the SARS-CoV-2 virus than non-reinfected participants.

In addition, neutralizing antibodies were less common in the serum-positive group (neutralizing antibodies were found in 45 (83%) of 54 uninfected individuals and 19 re-infections during the 6-week observation. Detected in 6 (32%) of infected participants).

Comparing the new infections between seropositive and seronegative participants, the authors found that the viral load of reinfected sera-positive recruits (measurable amount of SARS-CoV-2 virus) was infected sera-negative. We found that on average it was only 10 times lower than the participants in. This can mean some reinfection. Individuals may still have the ability to spread the infection. The author states that this requires further investigation.

In this study, most new Covid-19 cases were asymptomatic, 84% (16 of 19 participants) in the seropositive group, and 68% (1,079 participants) in the seronegative group. Of those, 732). No one was hospitalized.

The authors did not consider people with very low antibody levels after past infections, which may underestimate the risk of reinfection in previously infected individuals. I am aware of the restrictions.

They strongly suggest that even young people previously infected with SARS-CoV-2 will be vaccinated as efforts must be made to prevent and prevent transmission between this group. There is.