Epidemiology of SARS-CoV-2 Beta Variant (B.1.351) and Risk Factors for Severe Illness in the Southernmost Provinces of Thailand, April-September 2021

Abstract

        This study aimed to explore the epidemiology of the SARS-CoV-2 Beta variant (B.1.351) outbreak in the seven southernmost provinces of Thailand. A cross-sectional study was conducted on confirmed Beta variant cases. The surveillance and case investigation data of the Office of  Disease Prevention and Control 12 Songkhla were reviewed from 1 April to 30 September 2021. The Beta variant was confirmed in 551 cases (18.93%) out of 2,911 lineage-known SARS-CoV-2 cases. The top three highest proportions of Beta-variant cases were found in Narathiwat, Satun and Pattani provinces at 50.78%, 34.13% and 13.66%, respectively. Of all cases, 294 were male and 217 were female. The age range was 1–100 years (median 34 years). Most of cases were Thai (99.27%), most of whom were Muslim (96%). The first cluster of Beta variant was found in May 2021, while the peak of cases occurred in July 2021. Risk factors of the outbreak were gatherings in Islamic activities. The retrospective cohort study was conducted by reviewing outpatient cards and investigation documents of 286 patients (including 14 severely ill cases or deaths) who were diagnosed with Beta variant in Narathiwat and Satun from 1 April to 30 September 2021. The risk factors of severe or dead cases were age over 60 years (adjusted OR = 11.26, 95%CI: 2.42–52.59), chronic lung diseases (adjusted OR = 23.80, 95%CI: 1.23–458.61) and male gender (adjusted OR = 7.36, 95%CI: 1.02–52.76). Risk factors of the Beta variant outbreak were illegal influx across the Thai-Malaysian border and Islamic gatherings. Thus, the following should be undertaken: strengthening border surveillance to prevent illegal influx; banning religious gatherings, and improving vaccination coverage in elderly and chronically ill persons.