New ultra-contagious Omicron subvariants BA.4, BA.5 worsening California coronavirus wave

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.

“Because of the uncertainty of how exactly these new subvariants will affect us in L.A. County, it does remain important to use all of the measures that work to reduce COVID-19 risk,” such as vaccinations, masks, moving activities outdoors, increasing ventilation when indoors, testing and staying at home when sick, she said.

Though coronavirus reinfections have been possible throughout the pandemic, the risk has heightened of late.

“BA.4 and BA.5 are of special concern because of their apparent ability to cause reinfections in people who were already infected with other Omicron subvariants,” Ferrer said.

From early December, when Omicron’s presence was first detected in California, through the end of February, the state reported an average of about 14,325 people who were newly reinfected with the coronavirus per week, according to data from the California Department of Public Health.

That figure then receded along with the initial Omicron wave, with an average of 2,315 weekly reinfections reported from early March through early May.

But the metric has since shot up — with 10,409 weekly reinfections reported from mid-May to mid-June. That timeline roughly corresponds with when BA.4 and BA.5 started to circulate more widely.

“It is likely that increases in the total number of reinfections is a result of changes in the epidemiology of COVID-19, trends in case rates and vaccination,” as well as improvements in the realm of data compilation, including the implementation in February of automated processing for new reinfections, the California Department of Public Health said in a statement to The Times.

According to the latest figures from the U.S. Centers for Disease Control and Prevention, BA.4 and BA.5

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.