Characteristics of SARS-CoV-2 reinfection with Omicron BA.2.75 subvariants in Thai Adults.

Omicron subvariants of SARS-CoV-2 may resist vaccine- or infection-induced immunity thereby increasing the risk of reinfections in previously infected persons. This study aimed to investigate the clinical severity and the average time to the onset of Omicron reinfection. This survey study collected clinical data on Omicron reinfection. Information on time of infection, reinfection interval, overall clinical presentation, and severity of infection was reported. The total prevalence of symptoms among 201 participants was significantly higher in the first infection (risk difference (RD), 9.86%; 95% CI, 7.54-12.19]) compared to the second infection, and the hospitalization rate among all participants was significantly lower for the second infection than the primary infection (odds ratio (OR), 6.25; 95% CI, 2.158-24.71). The prevalence of symptoms compared with the first infection with pre-Omicron variants was similar to that of the first infection with the Omicron variant (RD, 2.56%; 95% CI, -6.14-1.01). However, the hospitalization rate for pre-Omicron primary infection was significantly higher (OR, 6.76; 95% CI, 2.87-15.87]) than that observed with Omicron variants. The severity of the primary infection and of a pre-Omicron variant was greater than that of a secondary infection or with an Omicron variant. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the Health Systems Research Institute (HSRI); the National Research Council of Thailand (NRCT); the Center of Excellence in Clinical Virology, Chulalongkorn University; and King Chulalongkorn Memorial Hospital; and the Second Century Fund (C2F), Chulalongkorn University. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocol was approved by the Institutional Review Board of the Faculty of Medicine of Chulalongkorn University (IRB numbers 750/65). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.