Latest estimates from the Centers for Disease Control and Prevention (CDC) indicated on Tuesday that BA.4 and BA.5 sub-variants of Omicron made up about 8% and 13% of all coronavirus cases for the week ending June 11, respectively.
The World Health Organization (WHO) added the BA.4 and BA.5 sub lineages to its monitoring list in March, and the strains have already been classified as variants of concern in Europe.
CDC’s sequencing data showed that BA.4 and BA.5 accounted for about 5% and 8% of cases a week ago.
According to the European Union’s disease prevention agency, the new variants are spreading faster than other variants which could cause more hospitalizations and deaths as they become predominant in the region.
Dr. Gregory Poland, head of Mayo Clinic’s vaccine research group in Rochester, Minnesota expressed concerns over the spread of the new subvariants noting that data from South Africa indicated their potential to evade immunity driven by vaccinations or prior infection.
BA.4 and BA.5 could potentially lead to a spike in COVID infections during summer as children return to schools and the efficacy of second booster shot drops, Reuters reported quoting Dr. Poland.
According to latest CDC estimates Omicron lineage BA.2 and its spinoff, BA.2.12.1 continue to drive a majority of U.S. COVID cases with ~64% and ~14%, respectively. BA.2 sub-variant of Omicron became dominant in the U.S. in late March.