No immunity? Studies show that COVID-19 reinfection is “common” in healthy young adults

New York – The worldwide number of cases of COVID-19 continues to increase, and a key issue in guiding public health efforts during a pandemic is that natural infection with SARS-CoV-2, the cause of viral disease, is against reinfection. Whether to bring immunity. Unfortunately, new studies show that this is not the case for everyone.

A study conducted by scientists at Ikarn Medical College and the Naval Medical Research Center on Mount Sinai is the first to assess the risk of reinfection in young adults. The authors of the study conclude that antibodies produced by natural infections may not be universally protected against reinfection.

“Our findings show that reinfection with SARS-CoV-2 is common in healthy young adults,” said senior author Dr. Stuart Sirphon. statement.. “Youth Need to be vaccinated As much as possible, as vaccination is needed to boost the immune response, prevent reinfection and reduce infection. “

Part of the COVID-19 Marine Corps Health Behavior Response (CHARM), this study measured the reinfection of more than 3,000 young and healthy US Marine Corps recruits over a six-week period. The study participants were mainly men aged 18 to 20 (92%).

Following two weeks of unsupervised home quarantine, new employees traveled in compliance For masking Social distance to monitored quarantine facilities, where they were offered the opportunity to enroll in the study. Nasal swabs were obtained from each of the 3,249 study participants at enrollment and tested for active SARS-CoV-2 infection by PCR.Blood samples were also evaluated for baseline antibodies SARS-CoV-2..

Of these participants, 3,168 who were negative for SARS-CoV-2 infection by PCR and underwent a final baseline antibody test continued under 2-week surveillance. Quarantine period.. During this time, the recruits were wiped with a cotton swab and PCR tested for infection two more times. In total, 3,076 participants who underwent three negative tests at the end of the second quarantine period were followed for an additional 6 weeks after transitioning to basic training.

Participants during the 6-week study period Tested again For new SARS-CoV-2 infections at Weeks 2, 4, and 6. Of the first 3,076 participants, 640 were either lost due to follow-up or excluded due to definitive test results. This left a total of 2,436 new employees, completing the survey.

Serum positive vs. serum negative

Research participants were classified as either Serum positive Or Cello negative, Based on baseline Antibody test.. Serum-positive individuals test positive for antibodies, indicating a previous infection. People with a negative serum response have a negative baseline antibody test, suggesting that they are more likely to have never been infected before.

Researchers report that young adults who are positive for serologic reactions have about one-fifth the risk of reinfection compared to individuals who are negative for seropositive reactions. Of the 189 participants who were serum positive at the beginning of the study period, 19 (10%) were positive by PCR at least once. In contrast, of the 2,247 seronegative participants, 1,079 (48%) were positive.

Within the seropositive group, researchers have found that antibody baseline levels Risk of infection.. They found that participants reinfected with SARS-CoV-2 had lower antibody levels than participants who were not reinfected.

Looking specifically at the levels of neutralizing antibodies, which are antibodies that can block infection, the results show that those who have re-infected have lower levels than those who have not. Only 32% of reinfected sera-positive individuals had detectable levels of neutralizing antibodies compared to 83% of non-infected sera-positive individuals.

Researchers also have measurable SARS-CoV-2, or Viral load, Between seropositive and seronegative participants. They report that the viral load of reinfected seropositive people is only one-tenth that of infected seronegative people on average. The authors state that the findings suggest that some re-infected individuals may spread the infection to others at the same rate as those who were first infected.

Doctors urge COVID-19 reinfection and take all precautions to prevent infection

“Despite the previous COVID-19 infection, young people can be infected with the virus again, yet Send to others“Dr. Sealfon explains. “This is an important point to know as the vaccine continues to roll out.”

The authors report that the clinical outcomes of the two groups are similar, with a majority (84% in the seropositive group and 68% in the seronegative group). Being asymptomatic.. None of the study participants were hospitalized or died.

As a limitation of the study, the authors warn that these results may underestimate the risk of SARS-CoV-2 infection in previously infected individuals. This is because it is unclear whether any of the seronegative participants may have been infected before, but there were not enough levels of antibody to detect.

The study is published at Lancet Respiratory Medicine..