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.
Additionally, “there’s strong evidence they can spread even faster than other subvariants,” said Los Angeles County Public Health Director Barbara Ferrer.
“There also have been some concerning findings in laboratory studies, which found that BA.4 and BA.5 were better able to infect lung cells than the earlier BA.2 subvariant of Omicron,” she said.
BA.4 and BA.5 are likely to affect countries and regions differently, depending on the overall level of immunity and the number of older and medically vulnerable people. But “all of the information to date points to the need for us to prepare for the likelihood of significant transmission in the upcoming weeks,” Ferrer said.
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