When Amanda Peet’s daughter, Molly, was just 8 months old, she contracted whooping cough, also known as pertussis. She had already received two of the three shots necessary to be fully immunized from this potentially fatal respiratory illness, which strikes 10,000 to 40,000 adults and children in the United States each year. For Peet, the situation was beyond terrifying. “She was sick–really, really sick–for six weeks,” she says (Molly, now 4, has fully recovered). The health scare reaffirmed Peet’s interest in advocating for vaccines around the world. She’d been vocal on behalf of smaller pro-vaccine organizations in the past but in 2012 was approached by the United Nations Foundation (UNF) to get even more involved. So last summer she traveled to kenya as an ambassador for their Shot@Life campaign, which offers free immunizations against illnesses such as measles, mumps, rubella (MMR) and polio. “Ever 20 second a child dies from a disease that could’ve been prevented by a vaccine that already exists,” says Peet.

For most people, vaccinations are just something doctors say you have to do, so you do it. Molly’s illness must have changed your perspective on their importance.
It did. It was particularly scary because we had potentially exposed a lot of our friends’ babies, who weren’t fully vaccinated yet. Thankfully, none of them caught it.

Are you surprised by the controversy surrounding vaccines in this country? 
It’s a very complicated and divisive issue. But in my family growing up, science was the thing. So I say what I always say: Look at the data. Talk to the scientists and researchers. Talk to pediatricians, biochemists, and vaccinologists. Don’t talk to people who don’t actually know what they’re talking about.

Is the pro-immunization movement working?
Domestically, yes. The fact that the 1998 study [linking the MMR vaccine to autism] was refuted was a huge turning point in the anti-vaccine fervor here. [The study was also retracted by the medical journal that originally published it.] But I’m still very concerned about the developing world, where children just don’t have access to vaccinations.

What took you to Africa with Shot@Life, and where did you focus your energy?
There was an outbreak of polio that required attention, so the first place we went was Nairobi. I went to some medical facilities where polio shots were being administered to children. Then we went southwest to Migori and visited a couple of villages that were also doing a polio campaign.

Is your impression that the communities understand the importance of vaccines?
We met a young boy whose mother and two siblings are blind. He had walked his little sister three miles to the community center to get immunized. The sense of communal parenting was an inspiration.

Are you optimistic that these diseases will get wiped out?
It’s so overwhelming. You feel like, God, I can’t do anything. How will we ever get this done? But they did it in India with polio. It was incredibly complicated, but they did it. So yes, I know we can do this.

–Kevin Hayes

For more, turn to page 96 of InStyle’s May issue, now available on newsstands and for digital download.