The number of new COVID-19 cases in Maine jumped Wednesday to the highest level in nearly six weeks as the latest version of coronavirus, omicron BA.2, raises infection rates across the Northeast.

Meanwhile, the Mills administration announced Wednesday that Maine schools will stop conducting pooled testing for the virus on May 13, in part because the BA.2 is so contagious that weekly tests are no longer as effective at keeping the virus out of schools. The administration said free at-home test kits, which it is providing to schools, are a better tool to prevent the virus from spreading among students and staff.

Maine reported 605 new cases of COVID-19 on Wednesday, the highest one-day total since March 4. The spike pushed up the seven-day average from about 200 cases a day to 255. The state also reported seven additional deaths.

The jump in new cases follows a slow rise in Maine’s case counts over the past two weeks.

Dr. Nirav Shah, Maine director of the Maine Center for Disease Control and Prevention, noted the overall upward trends in COVID-19 cases in a series of tweets Tuesday, although he also pointed out that hospitalizations have not increased by as much. Shah said the increases are being driven by the more contagious BA.2 omicron subvariant.

“What does all this mean? COVID is not over, though, as of now, it is not coming back with the same force as, say, BA.1 did in January,” Shah said.

The number of patients hospitalized in Maine with COVID-19 dropped to 94 on Wednesday from 103 on Tuesday. There were 20 patients in critical care and four on ventilators.

Maine hospitalizations hovered below 100 for most of the past three weeks after a steep drop from a peak of 436 patients on Jan. 13. Hospitalization counts also have remained stable in other Northeast states despite the rise in daily case counts.

New cases have begun rising nationwide, with the Northeast recording the most significant spike.

Maine has the fifth highest infection rate in the United States, with 142 cases per 100,000 residents over the past seven days, according to the U.S. Centers for Disease Control and Prevention. The national infection rate is 64.3 cases per 100,000 people.

Infection rates in Maine range from 261 cases per 100,000 people in Aroostook County to 77.5 in Piscataquis County. Cumberland County’s infection rate is 123.73 cases per 100,000 and York County has a rate of 114.6 cases per 100,000, according to the federal data.

The U.S. CDC data was last updated Tuesday and does not account for the jump in cases Maine recorded Wednesday. Washington, D.C., Rhode Island, New York and Massachusetts had the four highest infection rates.

On Tuesday, Philadelphia became the first major city in the United States to reinstate a mask mandate amid rising case numbers. Starting Monday, masks will again be required in indoor spaces in the city.A number of institutes of higher education – including Columbia University in New York and American University and Georgetown University in Washington D.C. – have also reinstated mask mandates.

But in Maine, the state is dropping one of its key strategies for reducing the spread of COVID in schools. The state plans to end pooled testing on May 13, the state Department of Health and Human Services announced Wednesday.

The department said pooled testing is significantly less effective with the extremely contagious BA.2 variant than it was with previous variants

Since May 2021 the state has funneled money to schools to test groups of students and staff for Covid. The federally funded program has cost an average of almost $2.5 million per month. A positive result in the group tests is followed by tests of individuals to find out who is infected. The surveillance testing has been used to identify infected individuals who don’t have symptoms before they can pass it along to others.

But the time between contracting BA.2 and showing symptoms is estimated to be much shorter than it was with previous variants – only 1.2 to 1.4 days, according to DHHS. And it usually takes longer than that – around two days according to DHHS – to get results from the PCR tests used for pool testing, defeating the purpose of the surveillance testing. Incubation periods for earlier strains of COVID have ranged between two to 14 days.

“Because the BA.2 variant is significantly more contagious than previous strains of the virus and given the longer time period to receive PCR results, the likelihood of detecting, identifying, and isolating an individual with COVID-19 through pooled testing before that individual has spread the virus to others is now significantly lower,” said DHHS.

To replace pooled testing, DHHS and the Department of Education will make 1.1 million at-home rapid test kits available to all K-12 schools in the state, enough to provide every student and school staff member one test kit with five to six tests. Rapid test results can come back in a matter of minutes. The department announced its plan to offer these free COVID tests to schools last week.

Schools can place orders for at-home tests up until Friday. DHHS said it will start shipping the kits to schools the week of April 25, and they may take a few weeks to arrive.

Xavier Botana, superintendent for Portland Public Schools, said he wants to learn more about why pooled testing is no longer an effective COVID mitigation strategy before calling off the program. However, at a Tuesday night school board meeting Botana noted that the school district has always followed the science when making decisions about COVID protocols and will continue to do so.

The Maine CDC also announced Wednesday it had overstated the number of Maine residents who were fully vaccinated by nearly 33,000.

The agency said some clinics misreported doses that had been used for second booster shots as the final doses of initial vaccinations. As a result, the number of people fully vaccinated was reduced from more than 1 million back to 996,919, or 74 percent of the Maine population.