LOS ANGELES — The growing dominance of two new ultra-contagious omicron subvariants is prolonging a wave of coronavirus cases in California and sparking growing concerns from health officials that coming weeks could see significant spread and increased hospitalizations.
BA.4 and BA.5 are now believed to be responsible for most new infections nationwide. The strains are of particular concern because they are not only especially contagious but also capable of reinfecting those who have survived earlier omicron infection.
When it comes to BA.4 and BA.5, their “superpower is reinfection,” said Dr. Peter Chin-Hong, a UC San Francisco infectious-disease expert.
