The beta variant was the most deadly of all the COVID-19 strains that the World Health Organization deemed variants of concern, according to a meta-analysis published Jan. 31.
The research, published in the International Journal of Infectious Diseases, analyzed 112 studies from multiple countries to determine the case fatality rates among five variants of concern. The studies were published between January 2020 and March 2023.
In order of severity, the meta-analysis found beta's death rate was 4.19%, gamma's was 3.6%, alpha's was 2.62%, delta's was 2.01% and omicron's was 0.7%. Researchers determined the death rates based on which variant was dominant during specific time periods.
More than two years have passed since the WHO has designated a SARS-CoV-2 strain as a variant of concern. Since then, "a substantial body of epidemiological research has accrued, forming a robust foundation for a comprehensive analysis of epidemic trends and [case fatality rate] levels during VOC epidemic periods," the researchers said.
Overall, the fatality rate during the period was 2.62%, with rates in North America slightly higher than the average at 2.67%. Limitations to the meta-analysis include the intensity of testing, which can differ between regions depending on vaccine availability and resource strains, such as exhausted healthcare workers, the authors said in conclusion.
More recently, virologists are testing the severity of JN.1, an omicron strain that accounts for more than 9 in 10 U.S. COVID-19 cases. The CDC has dismissed findings from Ohio State University researchers, saying there's "no evidence" the JN.1 variant is more severe than previous strains.