The outbreak of COVID-19, caused by SARS-CoV-2, has posed a severe threat to global public health. The omicron variant is less pathogenic and causes more asymptomatic infections, thus the emergency phase might have passed. Many governments are rolling back restrictions, and, as of Dec 19, 2022, there are 153 countries without any travel restrictions (data from Travel Off Path). However, the omicron variant shows a greater propensity for human-to-human transmission than previous variants and the wild-type strain.