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. 2022 Sep;15(9):983-985.
doi: 10.1016/j.jiph.2022.07.013. Epub 2022 Jul 28.

Immediate reinfection with Omicron variant after clearance of a previous SARS-CoV-2 infection

Antonella Mencacci  1 , Alessio Gili  2 , Barbara Camilloni  3 , Giulia Bicchieraro  3 , Roberta Spaccapelo  3 , Carla Bietta  4 , Fabrizio Stracci  5
Affiliations

Immediate reinfection with Omicron variant after clearance of a previous SARS-CoV-2 infection

Antonella Mencacci et al. J Infect Public Health. 2022 Sep.

Abstract

SARS-CoV-2 Omicron variant is spreading worldwide, causing unprecedented epidemic peaks due to its transmissibility and immune evasion. We searched in the archive of the Regional Microbiology Laboratory (Umbria, Italy) for immediate reinfection (i.e. infection occurring 25-60 days from primary infection) among 454,764 RT-PCR tests from 261,217 individuals. Lineage heterogeneity was assessed by S gene target failure phenomenon or whole genome sequencing. We found that BA.1 Omicron variant may cause immediate reinfection of patients just recovered from Delta infection. Immediate reinfection was not observed for any other combination of variants, including Delta over Alpha variant and BA.2 over BA.1 Omicron lineage.

Keywords: COVID-19; Delta; Omicron; Reinfection; SARS-CoV-2.

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Figures

Fig. 1
Fig. 1
Frequency of SARS-CoV-2 infection and Omicron BA.1 lineage reinfection in Umbria. Panel A, incidence of SARS-CoV-2 infection with circulating variants from the National Flash Surveys. These Surveys of the Italian Institute of Health are carried out every 2 weeks by WGS on a random sample of cases. Panel B, features of the four cases of reinfection identified during the October 2021 - January 2022 period, corresponding to the surge of Omicron BA.1 cases.
See this image and copyright information in PMC

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Supplementary concepts