Spend 10 minutes with actresses Alyson Hannigan and Sarah Michelle Gellar and the best friends vibes from their “Buffy the Vampire Slayer” days eases into the conversation.

Hannigan, who will always be “Lily” of “How I Met Your Mother” fame, was in town to spearhead the Ask2BSure campaign, a public health push to raise awareness about meningitis among parents of teens and young adults ages 16-23.

The two are moms to teens now: Hannigan to daughters Satyana, 16, and Keeva, who turns 13 this month, and Gellar to daughter Charlotte, 15, and son Rocky, 12. And both are partnering with GSK, a biopharma company, to encourage parents to talk to their child’s pediatrician about meningitis risk and vaccinations.

GSK is sponsoring “Pretty Hurts,” a Lifetime movie premiering June 28. It stars Haylie Duff and includes a storyline about meningococcal disease, or meningitis, an uncommon but serious illness that can be fatal.

It was Hannigan who told Gellar about the teen health issue, including how parents should ask about five kinds of vaccinations for different groups of meningitis.

“It’s funny because it kind of switched,” Hannigan said. “I always go to Sarah for advice because she’s an encyclopedia of knowledge.”

It didn’t take much for Gellar to get behind the campaign.

“This is such a huge transition time as a parent because you’re trying to start to give them autonomy and you want them to take over the accountability and to advocate for themselves,” she said. “This is when things really will fall through the cracks, and as a parent, I think we both feel this way. You don’t want to just protect your child. You want to protect everyone’s children.”

Pediatrician Dr. Aprel Barnes said parents are the best advocates for their teens and thus can discuss the seriousness of meningitis and the importance of prevention via vaccines.

The public health effort on Ask2BSure.com hopes to spark conversations between moms and their child’s pediatrician and others.

“So much information, especially as moms, we get from other moms, that’s where you learn so much of this stuff, so share it,” Gellar said.

Their hopes for their daughters are that “they take the good from us, and I hope that as we have grown older, we’ve learned certain things that we want to teach our children to do differently than we have and to look at the world differently” like not to take everything to personally and to have a thicker skin.

Both joke about how they’ll react when their oldest goes off to college (“I’ll be over here, broken in the corner,” Gellar deadpans.) They also appreciate how they’ve become part of many families’ lives and memories. (mine included.)

“That matters to me, that we’ve been really fortunate as an actor, you hope you do work that resonates, that means something, but also that stands the test of time,” Gellar said.

A “Buffy” reboot she is producing has created mounting excitement among their fans.

But their roles as moms aren’t going to take a backseat to anything.

Hannigan said she doesn’t even really remember life before motherhood, which is saying a lot considering her memorable television career.

Gellar said motherhood is a profound relationship.

“I have two little best friends for life.”