COVID-19 began as an outbreak in Wuhan, China, in December 2019 and was declared a pandemic by the World Health Organization (WHO) in March 2020 (WHO, 2020). The disease, caused by SARS-CoV-2, has affected >271,900,000 people worldwide and led to >5,000,000 deaths as of December 19, 2021 (WHO, 2021c). There are currently five SARS-CoV-2 variants that are classified as variants of concern: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and more recently, Omicron (B.1.1.529) (WHO, 2021b).
