The Massachusetts National Guard is expanding its mission to bus kids to school to make up for continuing shortages of drivers. Now if only they could serve school lunches.

The Guard expanded its bus-driving mission Thursday into Haverhill, Revere, Wachusett and Worcester, bringing the total to 13 districts where guard members are driving kids to school.

Baker first activated the National Guard to help with the driver shortage in September.

Pam Reipold of the School Transportation Association of Massachusetts says there are a number of reasons for the scarcity of drivers.

“Often school bus drivers were older folks. They just don’t need this right now, right?” Reipold said. “With all the worry that comes along with the pandemic ... now’s a good time to retire.”

One holdup, Reipold said, is the slow process of onboarding a new driver between the vetting, licensing and testing. She said that the process needs to be streamlined while maintaining high standards.

But the pandemic-related shortages don’t stop once children get to school. Cafeterias are facing widespread shortages, too, of both staff and supplies, said Deb Mugford of the School Nutrition Association of Massachusetts.

“Number one is the supply chain, supply disruption issues,” she said. “Naturally, the number-two concern is the labor shortage that we have in our child nutrition programs.”

Kids are still being fed nutritious meals, Mugford said, but they may not have the “Pizza Fridays” that they’re used to due to the unpredictability of ingredients.

Nationally, 97% of nutrition directors are worried about supply chain issues, a July survey found — with staff shortages just behind at 90%.

“I have not spoken to one food service director yet that did not have a staffing issue,” Mugford said. “I mean, it’s crazy.”

Mugford said she could not pinpoint the cause of the staff shortages, though she noted that most of the open positions are part time.

“A pandemic happened. Here we are,” she said. “I can't speak on behalf of why people don't do something, I can just tell you that it is truly a significant issue.”