With over 500 million COVID-19 cases and more than 6 million deaths, the COVID-19 pandemic remains a global health threat maintained by the impact of a changing virus. Emerging SARS-CoV-2 variants have changed the endgame of the COVID-19 pandemic. As new variants and/or subvariants emerge by virtue of mutations in the virus, there is a risk of new surges of infection. To date, the three globally dominant SARS-CoV-2 variants have been D614G, Delta and Omicron. Omicron subvariants BA.1 and BA.2 were the causes of majority of COVID-19 infections over the last few months around the world but are currently being overtaken by BA.4 and BA.5 in South Africa. The impact of new variants varies in individuals in relation to age, vaccination status and time since last vaccine dose; nevertheless, COVID-19 vaccines still offer individual and community benefits. The various vaccines have had varying effectiveness in preventing asymptomatic and clinical infection but have proven to be highly effective in preventing severe disease, hospitalization and death over time for all past variants. Vaccines also lower secondary attack rates, ie. they reduce SARS-CoV-2 transmission to contacts such as household and workplace contacts. Secondary attack rates are lower because vaccinated individuals who get infected are less infectious due to a lower viral load and a shorter duration of infectiousness. Waves of infection can continue to be expected if past trends continue. In South Africa, a new surge of infections driven by BA.4 and BA.5 may lead to a fifth wave of COVID-19 infections.
1. Describe the global epidemiology of SARS-CoV-2 infection.
2. Describe the impact of SARS-CoV-2 variants on the trends of the ongoing pandemic.
3. Discuss the individual and community benefits of Covid-19 vaccines.