ECDC ups BA.4, BA.5 to variants of concern, warns of case rises

The European Centre for Disease Prevention and Control (ECDC) last week designated the BA.4 and BA.5 Omicron subvariants as variants of concern (VOC) and said they could fuel increases in infections in the region in the weeks and months ahead.In US developments, key outbreak markers continue to rise, especially in the Northeast and Midwest.New subvariants will soon dominate in PortugalIn an update on variants of concern as of May 12, the ECDC has BA.4 and BA.5 on its current VOC list, alongside the Delta variant, the original Omicron variant (BA.1), and BA.2, the earlier Omicron subvariant.

BA.4 and BA.5 were first detected in South Africa in January and February, respectively, though it's not clear where they originated.In a May 13 epidemiologic update, the ECDC said BA.4 and BA.5 have already become dominant in South Africa, and Portugal's health ministry estimates that BA.5 as of May 8 already accounts for about 37% of cases.

The ministry added that Portugal's increasing proportion of BA.5 subvariant cases has also come with rising case numbers and rising COVID-19 test positivity.With 12% to 13% growth advantage over BA.2, the ECDC estimated that BA.5 will become dominant in Portugal by May 22.The growth advantage is probably due to immune escape from earlier infection, including from the original Omicron variant, and vaccination, for which protection against Omicron viruses has been shown to wane over time.Infections from BA.4 and BA.5 could significantly increase in Europe in the coming weeks and months, and though limited data don't suggest increased severity, a substantial increase in cases could put pressure on hospitals and intensive care units—similar to earlier Omicron surges.