BOSTON (AP) — Gov. Charlie Baker activated up to 450 members of the Massachusetts National Guard on Tuesday to help deal with COVID-19 challenges.

Up to 200 guard members will aid in COVID-19 testing in schools throughout the state, and as many as 250 members will be available to offset potential staff shortages at the state Department of Correction due to a vaccine mandate.

More than 2,200 schools have currently signed up to participate in at least one of three types of COVID-19 testing: test and stay, symptomatic testing, and pooled testing, which allows schools to test samples in batches and then individually if COVID-19 is detected in the pooled batch.

Since the beginning of the school year, results from pooled testing show pool positivity rates of less than 1%, and test and stay — which is used to test close contacts — has saved about 25,000 school days for students who would have otherwise had to quarantine, the Republican governor said.

Guard members will begin training this week and begin administering COVID-19 testing in selected schools Monday as school-based testing continues to ramp up, Baker said.

“Today’s activations will ensure that we have additional staffing support for our school testing programs to help kids stay safe,” Baker said in a press release.

Baker said National Guard members are also preparing to respond to possible staffing shortages at the Department of Correction due to noncompliance with an executive order issued by Baker requiring all Executive Department employees demonstrate proof of vaccination against COVID-19 by Oct. 17.

Activating the Guard in advance of the deadline will allow members to immediately begin job-specific training, Baker said.

Under the plan, National Guard personnel will take over tasks that do not involve direct contact with inmates. When Guard personnel assist with providing transportation to inmates, a correctional officer will accompany them.

The two missions won’t interfere with the National Guard’s ability to respond to and assist in emergencies within the state, Baker said.

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THE NUMBERS

The number of new daily cases of COVID-19 increased by more than 4,400 over the long holiday weekend, while the number of newly confirmed coronavirus deaths in Massachusetts rose by 36.

The new numbers from Friday, Saturday, Sunday and Monday pushed the state’s confirmed COVID-19 death toll to 18,394 since the start of the pandemic, while its confirmed caseload rose to nearly 773,000.

There were more than 540 people reported hospitalized Tuesday because of confirmed cases of COVID-19, with more than 140 in intensive care units.

The average age of those who have died from COVID-19 was 72.

The true number of cases is likely higher because studies suggest some people can be infected and not feel sick.

More than 4.6 million people in Massachusetts have been fully immunized against COVID-19.

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BREAKTHROUGH CASES

The number of fully vaccinated people who have tested positive for COVID-19 since the start of the pandemic in Massachusetts is continuing to increase.

In the past week — from Oct. 2 to Oct. 9 — the number of breakthrough cases of the virus jumped by more than 4,000 — from 40,464 to 44,498.

The breakthrough cases still amount to less than 1% of fully vaccinated people, and health officials say the vaccine offers strong protection against getting infected and decreases the chances of hospitalization and death.

Of the recorded breakthrough infections in Massachusetts since the start of the pandemic, about 1,400 resulted in hospitalization and 345 resulted in death, according to the state Department of Public Health.

COVID-19 cases in vaccinated people are counted as those who test positive more than 14 days after the final dose of vaccine.