HARRISBURG, Pa. (AP) — Pennsylvania’s two-month-old coronavirus exposure notification app can now be used by mobile phone users as young as 13 as health officials work to stop the virus' spread in schools around the state, officials said Monday.

The app, named COVID AlertPa, had previously been limited to people 18 and over.

“By expanding the age range, middle- and high-school students will be able to add their phones to the fight and help in contact tracing that occurs in their schools if a positive case is identified,” state Health Secretary Dr. Rachel Levine said at a virtual news conference.

A parent or legal guardian must approve the minor’s use of the app, she said. So far, more than 627,000 mobile phone users have downloaded it, according to the state.

Some school districts continue to conduct in-person instruction, even though each of Pennsylvania's 67 counties — except for northwestern Pennsylvania's rural Cameron County, with fewer than 5,000 residents — has passed the threshold of new cases where the state Department of Education recommended fully remote instruction.

Approximately 20% of schools are offering full in-person instruction, 30% are offering some in-person instruction and 50% are fully remote instruction, the Department of Education said Monday.

Pennsylvania is now reporting an average of more than 6,400 new virus cases each day over the last week of November, triple the number from the last week in October. Hospitalizations, deaths and the testing positivity rate are up sharply, as well.

Meanwhile on Monday, the state Republican Party, in a fundraising email, accused Gov. Tom Wolf of “a whole new level of government overreach” and “abusing government permission to use wireless data" by using the Wireless Emergency Alert system last Wednesday night.

In the message, Wolf's administration urged people to “stay home if possible” because “COVID-19 rates are rising & hospitals could soon be at capacity.”

The GOP's fundraising email, though, characterized it as Wolf, a Democrat, of having “ordered us not to leave our homes by sending a mass text."

"Emergency text alerts are sent for just that, emergencies,” it said.

President Donald Trump declared a nationwide coronavirus emergency in March, and the Federal Communications Commission has advised state and local governments that they can use the Wireless Emergency Alert system “as a tool to provide life-saving information to the public” during the pandemic.

Maryland's Republican Gov. Larry Hogan also used the system Wednesday, as governors and mayors ratchet up mask mandates and restrictions on indoor gatherings. Public health officials fear that Thanksgiving gatherings will put greater stress on strained hospitals and lead to an even bigger spike in sickness and death over the holidays.

In Allegheny County, Dr. Debra L. Bogen, director of the county's health department, said in a statement Monday that she expects rising cases of Covid-19 from Thanksgiving gatherings and travel and is concerned that, if cases continue rising at the current rate, “it will strain the capacity and staff of our region’s hospitals.”

Two weeks ago, Wolf's administration mandated people who are traveling to Pennsylvania from another state, as well as Pennsylvania residents who are returning home from out of state, to quarantine for 14 days if they do not test negative for the virus within 72 hours before they arrive.

The state has no plans to enforce that measure, but is asking for voluntary compliance.

Levine on Monday urged people who attended Thanksgiving gatherings to consider getting a test or going into quarantine, and urged people not to travel during December's upcoming holidays.

Before a vaccine is available, the upcoming winter months, Levine said, look like they will be “the peak time in terms of transmission of COVID-19 for this global pandemic.”

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This story has been corrected to show that one county, Cameron County, does not meet the new cases threshold where the state Department of Education recommends fully remote instruction.

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Follow Marc Levy on Twitter at https://www.twitter.com/timelywriter. Follow AP coverage of the pandemic at https://apnews.com/UnderstandingtheOutbreak.