Incidence and severity of SARS‐CoV‐2 reinfection, a multicenter cohort study in Shanghai, China

Abstract

During March 2022 to January 2023, two Omicron waves hit Shanghai and caused a massive number of reinfections. To better understand the incidence and clinical characteristics of SARS‐CoV‐2 reinfection in Shanghai, China, we conducted a multicenter cohort study. COVID‐19 patients first infected with BA.2 (March 1, 2022–May 23, 2022) who were quarantined in Huashan Hospital, Renji Hospital, and Shanghai Jing'an Central Hospital were followed up for reinfection from June 1, 2022 to January 31, 2023. Of 897 primary infections, 148 (16.5%) experienced reinfection. Incidence rate of reinfection was 0.66 cases per 1000 person‐days. Female gender (adjusted odds ratio [aOR]= 2.19, 95% confidence interval [CI]: 1.29–3.83) was a risk factor for reinfection. The four most common symptoms of reinfections during the circulation of BA.5 sublineages were cough (62.59%), sore throat (54.42%), fatigue (48.98%), and fever (42.57%). Having received a booster vaccination was not associated with reduced severity of reinfection in comparison with not having received booster vaccination. After matched 1:1 by age and sex, we found that reinfections with BA.5 sublineages had significantly lower occurrence and severity of fever, fatigue, sore throat, and cough, as compared to primary infections with BA.5 sublineages. SARS‐CoV‐2 Omicron reinfections were less severe than Omicron primary infections during the circulation of the same subvariant. Protection offered by both vaccination and previous infection was poor against SARS‐CoV‐2 reinfection.

The symptoms and interval of Omicron SARS-CoV-2 reinfection among healthcare workers in a hospital of Southern China: a cross-sectional study

“…In this study, the reinfection rate among HCWs was 11.5%. This is similar to previous studies [ 22 , 23 ]. The reasons for COVID-19 reinfection are multifaceted, primarily including low antibody levels, the shortened duration of immune protection provided by antibodies, the mutation of viral strains, non-adherence to epidemic prevention measures by the population, hesitancy towards vaccination, and public fatigue due to the prolonged pandemic.…”

“…It is also relevant to note that the younger HCWs are more susceptible to infection and reinfection compared to relatively older ones in Omicron wave [ 37 ]. Previous studies have reported that females are more susceptible to COVID-19 [ 12 , 38 ] and have a higher risk of reinfection [ 23 ]. In the results of a previous study, most of cases are nurses (48%), followed by physicians (25%) and other HCWs (23%) [ 39 ], which are similar to the results of our study.…”

“…On the other hand, the effectiveness of the first infection against reinfection declines over time since first infection [ 45 ]. More importantly, protection offered by both vaccination and previous infection are not completely effective against SARS-CoV-2 reinfection [ 23 ]. Ana Rubia Guedes et al found that the mean interval between infections in days (range) is 507 (122–674) days (approximately 16 months) in Omicron period during 1 January and 10 March, 2022 [ 27 ].…”

“…The interval between primary pre-omicron infection and pre-omicron or omicron reinfection was reported to range from 45 to 672 days [ 26 , 27 ]. Most of the reinfected patients are asymptomatic, with milder symptoms or symptoms similar to those of the first infection [ 20 , 23 ]. However, the interval and symptoms of Omicron reinfection compared to the first Omicron infection remain poorly studied.…”

Hybrid Immunity and the Incidence of SARS-CoV-2 Reinfections during the Omicron Era in Frontline Healthcare Workers

“…Both types of study have shown that natural and artificial immunity both wane over time and have led to the adaptation of recommendations regarding vaccination schedules [ 8 , 17 , 19 , 27 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. Common epidemiological indicators of frequency in other studies showed increases in the number of reinfections and primo-infections in the Omicron era, similar to our study [ 25 , 26 , 43 , 44 ]. The previously published study on the first SARS-CoV-2 infection, on the same population of HCWs, showed a higher severity of the cases registered in HCWs from the high-risk departments [ 18 ].…”