A Portland mannequin wears a mask on Tuesday Dec. 28, 2021. Credit: Troy R. Bennett / BDN

The more contagious “stealth omicron” variant now accounts for the vast majority of new COVID-19 cases in Maine with transmission looking to tick upward here.

The greater prevalence of the BA.2 variant comes as Maine’s top health official warned earlier this week that wastewater testing data showed the virus may be back on the rise in Maine. The highly contagious strain, first identified in Maine in late February, has driven up overall cases significantly in some European countries.

In cases sampled by Walgreens over the past week, the more contagious strain accounted for between 71 and 89 percent of Maine cases, according to company data. That is up from between 12 percent and 20 percent of samples analyzed in the first week of March here.

Like the original omicron strain, the BA.2 variant seems to be less severe on average than earlier versions of COVID-19. But it still can cause severe disease and poses other challenges for health officials. Federal regulators announced earlier this week that they were halting use of a COVID-19 antibody treatment that was no longer effective against the new strain.

Other treatments, including antiviral pills, remain effective against the variant and available to high-risk patients in Maine. So far, the rise of the BA.2 variant has not been accompanied by a marked increase in hospitalizations, although hospitalizations tend to trail new virus cases.

As of Thursday, 95 patients were hospitalized statewide with the virus, with 23 in critical care beds and four on ventilators. Hospitalizations briefly rose above 100 this week for the first time in two weeks.