BA.2 rise across U.S. evident even with diminishing test data

This month the Omicron BA.2 subvariant has flattened the steep downward glide in official case counts that Boston and the rest of the country had been on after the BA.1 surge in the winter. The turn is not unexpected, but it comes as in-person gatherings have resumed, vaccinations have flatlined, officially reported tests are falling and politicians and many Americans want an end to most restrictions.

And while hospitalizations and deaths remain on the decline nationally, concerns are rising for unvaccinated and unboosted people, who remain more vulnerable to serious illness and death.

BA.2, which is more transmissible and has spread even faster than BA.1, has quickly risen to account for what the Centers for Disease Control and Prevention estimates to be 86 percent of all U.S. cases. Twenty states, including the entire Northeast, have seen their daily cases rise by at least 30 percent in the past two weeks. Experts believe that two new subvariants may be contributing to this growth.