CORONAVIRUS DISEASE-2019 CHARACTERISTICS AMONG THAI ADULTS REINFECTED WITH SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS-2

Abstract

Some severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) omicron subvariants may be resistant to vaccines and/or infection-induced immunity increasing the risk for reinfection.  In this study, we aimed to determine coronavirus disease-2019 (COVID-19) severity, need for hospitalization, symptoms and time to reinfection with SARS-CoV-2 among previously infected Thai adults in order to inform efforts to control COVID-19 in Thailand.  The study subjects were Thais aged >18 years, currently living in Thailand who had two previous COVID-19 infections at least 90 days apart confirmed by either an antigen test or COVID-19 real-time polymerase chain reaction testing, where the reinfection was presumed to be an omicron variant based on the most prominent strain of COVID-19 occurring at the time of reinfection.  Study subjects were recruited via advertisements on the social media applications Line and Facebook.  Each subject was asked to complete an online questionnaire asking about demographic data, dates of COVID-19 infections, time from the initial infection to reinfection, severity of infection, hospitalizations and symptoms during both infections.  The minimum number of subjects determined to be needed for the study was 220.  The study was conducted during 12-31 January 2023.  A total of 201 subjects were included in the study, 59.7% female.  The mean (±standard deviation (SD)) age of study subjects was 44.3 (±11.4) (range: 20-81) years.  The symptoms significantly more common in the first infection than the second infection were: anosmia (36.8% vs 13.9%) (p<0.001), dyspnea (36.3% vs 18.9%) (p<0.001) and myalgia (60.2% vs 43.8%) (=<0.001), respectively.  The hospitalization rate was significantly higher during the first infection than the second infection (14.9% vs 3.5%; crude odds ratio (cOR) = 6.25; 95% confidence interval (CI): 2.16-24.71; p<0.001).  The average time from first infection to reinfection was 263 (range: 96-725) days.  In summary, anosmia, dyspnea, myalgia, and hospitalizations were more common during first than the second COVID-19 infection among study subjects and the time between infections averaged 9 months.  We conclude, as COVID-19 immunity decreases over time, there is a need for a booster, possibly updated, vaccine to reduce the risk for reinfection.