The risk of SARS-CoV-2 reinfection in people who have recovered from COVID-19

This article is from the NEJM Journal Watch Elucidating Reinfection After COVID-19 to clarify the reinfection after COVID-19.
Comment by Thomas Glück, MDSARS-CoV-2 high-risk groups of reinfection include adults, women, and immune People with low function and those who have been hospitalized with COVID-19
.

The possibility of re-infection of SARS-CoV-2 in people who have recovered from COVID-19 is known, but the incidence and severity of re-infection (and related immunological risk factors) are still unclear
.

Two recent studies provide some evidence
.

Slezak et al.
conducted a retrospective observational study
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The study included> 75,000 California HMO members who were diagnosed with COVID-19 by PCR between March and October 2020
.

The researchers assessed the situation of SARS-CoV-2 (indicating re-infection) in the above-mentioned participants as of January 2021 (mean follow-up period, 270 days), 90 days after the initial infection
.

Among the 315 suspected re-infection patients, there were more women than men (1.
0% vs.
0.
7%, P=0.
002; adjusted hazard ratio, 1.
4)
.

Other significant risk factors include weakened immune function (risk ratio, 2.
5), hospitalization during the first infection period (risk ratio, 1.
6), and first infection after March/May 2020 (risk ratio, 1.
3 [June/August]; Hazard ratio, 2.
3 [September/October]) and adults (risk ratio range, 2.
2 to 2.
7)
.

The hospitalization rate for re-infection was higher than that of the first infection (11.
4% vs.
5.
4%)
.

Peghin et al.
tracked 546 people (mean age, 53 years; 54% women) diagnosed with COVID-19 from March to May 2020 in a medical center in Italy; prospective follow-up included monthly serological tests (median Duration, 10 months)
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The IgG seroconversion rate at 2 months is 100% (moderate to critically ill patients) to 54% (asymptomatic patients)
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At 10 months, 47% of people can no longer detect antibodies
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Six people were re-infected 9 months (median) after the initial infection
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Two of them were sero-negative, 2 were sero-negative, and 2 were sero-positive
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All 6 people had mild symptoms when they were first infected, and had mild or asymptomatic symptoms when they were re-infected
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In summary, these studies indicate that the risk of re-infection after recovering from COVID-19 is 1%
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Among the factors related to reinfection, the mechanism of certain factors (such as women’s high risk of reinfection) needs further study
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Other factors seem to be easier to explain (for example, patients with low immune function are at higher risk of re-infection)
.

In addition, it is necessary for us to clarify the risk of infection for people who have never had COVID-19 after being vaccinated
.

My own research (Infection 2021 Sep 25) and other studies have proven that after COVID-19 survivors are injected with booster shots, the level of anti-SARS-CoV-2 antibodies increases significantly, which may be further reduced compared to relying solely on natural immunity Risk of re-infection
.

Commented article [1] Slezak J et al.
Rate and severity of suspected SARS-CoV-2 reinfection in a cohort of PCR-positive COVID-19 patients.
Clin Microbiol Infect 2021 Jul 28; [e-pub].
(https: //doi.
org/10.
1016/j.
cmi.
2021.
07.
030)[2] Peghin M et al.
Low risk of reinfections and relation with serological response after recovery from the first wave of COVID-19.
Eur J Clin Microbiol Infect Dis 2021 Aug 11; [e-pub].
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