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. 2021 Dec;40(12):2597-2604.
doi: 10.1007/s10096-021-04335-x. Epub 2021 Aug 11.

Low risk of reinfections and relation with serological response after recovery from the first wave of COVID-19

Maddalena Peghin  1 , Emilio Bouza  2   3   4   5 , Martina Fabris  6   7 , Maria De Martino  8 , Alvisa Palese  9 , Giulia Bontempo  10 , Elena Graziano  10 , Valentina Gerussi  10 , Valentina Bressan  9 , Assunta Sartor  6 , Miriam Isola  8 , Carlo Tascini  10 , Francesco Curcio  6
Affiliations

Low risk of reinfections and relation with serological response after recovery from the first wave of COVID-19

Maddalena Peghin et al. Eur J Clin Microbiol Infect Dis. 2021 Dec.

Abstract

The aim of the study was to assess reinfection rates in relation to long-term antibody dynamics against SARS-CoV-2 after the first wave. A prospective longitudinal study with monthly serological follow-up during the first 4 months, and then at 6, 8, and 10 months after the disease onset of all recovered adult in- and outpatients with COVID-19 attending Udine Hospital (Italy) from March to May 2020. During the follow-up, reinfections were collected. A total of 546 unselected individuals with COVID-19 acquired from March to May 2020 were included (292 female, mean age 53 years). After a median follow-up of 10 months (IQR 6.2-10.4), reinfection occurred in 6 (1.1%) patients, median age of 44.5 years (IQR 33‒49). All had a previous history of mild COVID-19 (all were healthcare workers) and reinfection occurred a median of 9 months (IQR 8.2‒10.2) after the onset of the first episode. Patients with reinfection were either seronegative (2/56, n = 3.6%), seroreverted (2/137, 1.5%), or seropositive (2/353, 0.6%) (p = 0.085). All reinfections were mild (n = 5) or asymptomatic (n = 1). After reinfection, none of patients developed IgM response and only two had a transitory boosted IgG immunization response. In an unselected population after the first wave of COVID-19, after a prolonged observation period (mean 10 months), reinfection was very uncommon; occurred in patients with a previous history of mild infection, mostly with weak or absent serological response; and manifested with mild or asymptomatic clinical presentation.

Keywords: COVID-19 reinfection; Longitudinal study; SARS-CoV-2 IgG; SARS-CoV-2 IgM; SARS-CoV-2 antibodies; SARS-CoV-2 reinfection; SARS-CoV-2 serology.

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Conflict of interest statement

MP reports receiving grants and personal fees from Pfizer, MSD, Thermofisher and Dia Sorin outside the submitted work. CT has received grants in the last two years from Correvio, Biotest, Biomerieux, Gilead, Angelini, MSD, Pfizer, Thermofisher, Zambon, Shionogi, Avir Pharma, and Hikma unrelated to the study submitted. The other authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Reinfection and serological follow-up (up to February 2021): flow diagram of in- and outpatients with COVID-19 included
Fig. 2
Fig. 2
Humoral IgM and IgG response of reinfected patients. Patient 1—blue line; patient 2—green line; patient 3—yellow line; patient 4—red line
See this image and copyright information in PMC

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