Health officials have not observed a change in severity among people infected with the omicron "sister variants" BA.4 and BA.5, Maria Van Kerkhove, PhD, COVID-19 technical lead for the World Health Organization, said during an April 13 media briefing.
The WHO began tracking the sublineages — which have been detected in at least five countries — April 11. So far, there are fewer than 200 sequences of the variants available in a global database for analysis. Among these cases, health officials have not detected any changes in the epidemiology of infected people compared with those infected with previous omicron sublineages, according to Dr. Kerkhove.
"We haven't really seen any change in that epidemiology; we have not seen a change in severity," she said.
The WHO is working with experts across the globe to track BA.4 and BA.5 in real time to monitor changes in transmissibility, severity and efficacy with diagnostics and vaccines.