Boston-area COVID wastewater rises as BA.5 variant takes over: ‘More infectious and evading some prior immunity’

The closely watched Boston-area COVID wastewater data is rising yet again as the omicron BA.5 variant spreads across the region and infectious disease experts warn of a “summer wave.”

The predictive wastewater tracker shows that average virus sewage samples have jumped 29% in the south of Boston region during the last two weeks — from 548 copies per milliliter to 709 copies.

In the north of the city region, the average has increased 28% over the same time frame — from 567 copies to 728 copies.

Meanwhile, the BA.5 variant is gaining steam across the region. The highly contagious variant accounts for 59.7% of new cases in New England, according to the CDC variant tracker.

“I’m getting more concerned that we are going to have a summer wave different from previous years,” said Matthew Fox, a Boston University School of Public Health epidemiology professor. “Usually our waves are more at the end of the summer or start of the fall. Here we might be starting to see one beginning with the increase in BA.5 being more infectious and evading some prior immunity.

“I’m not ready to conclude that this will be a big wave and certainly we still have effective tools to fight the severity of illness,” he added. “But it does mean people should be sure to get boosters if they have not already and wearing masks in indoor gatherings is a helpful precaution for reducing risk.”

Because the variant appears to be more transmissible and can better escape immunity, there’s a potential risk for at least a moderate rise in infections this summer or early fall, said Davidson Hamer, a Boston University School of Public Health infectious disease specialist.

Hamer added, “Higher-risk individuals, especially those who have not been vaccinated, older members of our population, and those with underlying diseases or clinical states that increase risk need to be cautious over the next few months.”