Super contagious, able to reinfect: California faces big coronavirus risk from BA.4, BA.5

Are people in your life being infected with the coronavirus, even after being caught up in an earlier wave?

You aren’t alone. For the third straight year, the arrival of summer has brought fresh uncertainties about the COVID-19 outlook in California.

The latest development upending the pandemic landscape is the growing dominance of two subvariants — BA.5 and, to a lesser degree, BA.4 — that not only are ultra-contagious but have shown the ability to reinfect those who contracted earlier Omicron strains.

This combination of initial and recurring infectivity carries enormous implications. Here’s what we know:

How common are BA.4 and BA.5?

According to the latest figures from the U.S. Centers for Disease Control and Prevention, BA.5 comprised an estimated 53.6% of new cases nationwide for the weeklong period that ended Saturday. This completes a stunning rise to dominance for the subvariant, which only a month ago was thought to be responsible for a bit less than 10% of new cases.

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