For three years, Stacy Hillenburg has made it her business to know about other people’s vaccinations and immunizations. She’s not being nosy. For her 3-year-old son, it could be a matter of life and death. When he was seven weeks old, he received a heart transplant because of dilated cardiomyopathy, a disease of the heart muscle, and he’s had to take immune suppressants ever since. As a result, he can’t have live vaccines, and his health depends on the health — including the immunity — of those around him.

So when one of her friends wanted to vaccinate her child on a selective schedule, or wait until a certain age to vaccinate, Hillenburg had to be adamant. She was not going to let her son see that friend’s child until the child had gotten MMR (Measles, Mumps and Rubella) shots. “We still talk and everything,” Hillenburg said, but “it’s hard to have to deal with that kind of thing with your friends. On the other hand, I do have to keep my son protected. It’s just one of those things where they can’t be together.”

As growing anti-vaccination sentiment and an ongoing measles outbreak together have sparked a fervent blame game over who or what is responsible, parents are reconsidering the best ways to protect their children, vaccinated or not, during playdates, birthday parties and other social events. To some, asking a parent about another child's vaccination history is necessary, even if impolite, while others who oppose vaccination argue that they are unfairly victimized and blamed for such outbreaks. It's a touchy, ideologically fraught dispute, but a subject parents feel they have to broach if they want their children to have social lives but also be protected. 

Hillenburg, who lives in Bowling Brook, Illinois, decried the fact that by choosing not to get immunizations, anti-vaxxers, as such people are nicknamed, put others at risk, her son and other immuno-suppressed people among them. If she could, “I would get him the MMR in a minute. I’d be down at the doctor’s office tomorrow if it were safe for him.” Her two daughters, aged 6 and 7, are up to date with their shots.

For unvaccinated children, “the only reason they’re protected is because everyone else is vaccinating,” Dr. Jane Seward, a medical epidemiologist with the Centers for Disease Control and Prevention (CDC), explained. If an unvaccinated child is healthy, he or she does not threaten to transmit a disease to another, but “the risk is there because of the unvaccinated child.” A vaccinated child is highly unlikely to pass on a disease — the MMR vaccine is 97 percent effective, for example, at preventing someone from catching or transmitting measles.

As the measles outbreak flourishes — the CDC reported 102 cases in 14 states in January — a major contributor to the mayhem and controversy over vaccinations is a debate over fact versus fiction. “Vaccines protect,” Seward said firmly. “No vaccine is 100 percent protective,” but vaccinated people have “drastically reduced” the risk of acquiring certain diseases or passing them on to others, and the benefits of vaccinating far outweigh the risks. The majority of those who contracted measles in the United States in 2014, when 644 cases were reported in 27 states, were not immunized, according to the CDC.

Balancing Manners And Health

“From a social standpoint, it’s not appropriate to be asking people about their medical history,” Lizzie Post, an author and spokesperson for the Emily Post Institute, which specializes in teaching etiquette, said. “People might be offended that you ask." If a parent does decide to ask if a child is vaccinated, Post recommended he or she should not be judgmental about the answer.

Last year, parents were asking so many questions about vaccines and with whom to let their children play that Every Child by Two, a vaccine advocacy group based in Washington, D.C., commissioned a series of blog posts to discuss the matter, said Amy Pisani, the group’s executive director. The first, titled “Ask Before They Play To Keep Chickenpox, Pertussis and Measles Away,” tried to answer questions such as “What do you do when you discover your child’s best friend is unvaccinated?” and, of course, “Is it any of your business?”

Those questions, and the fact that they are being asked at all, highlight what some see as a grey zone between being proactive to protect one’s child and being unfairly accusatory. The queries also reflect mounting parental anxiety as social norms shift to reflect increasingly popular doubts about vaccinations and health risks.

To Vaccinate Or Not To Vaccinate

Barbara Loe Fisher, co-founder and president of the National Vaccine Information Center, said unvaccinated “people are being marginalized, demonized, blamed” for outbreaks of disease. She called it “very premature to be pointing the finger at a tiny percentage of people who are unvaccinated.”

Fisher’s organization takes “a very pro-informed consent position,” where one has the choice to obtain all government-recommended vaccines, or some of them, or none at all. “What we do about that is a matter of personal choice,” she said. Of parents asking others if their children have been vaccinated, she said, “We have the right to ask each other these questions.”

On March 1, 2004, when her eldest daughter, Calinda, was 14 months old, Shannon Strayhorn of St. Louis took "Cali" for her regular immunizations, two months later than usual only because the doctor’s office had been so busy. “We followed the schedule to a T,” Strayhorn recalled. Until then, Cali had been developmentally perfect in every way. “She hit every milestone on time,” Strayhorn remembered. 

Not long after, Cali stopped speaking, instead screaming “this unbelievable scream that just went on 16 hours a day,” Strayhorn said. “She lost motor skills. Basically, she just disappeared." About six months later, Cali was diagnosed with autism. Strayhorn said doctors didn’t help — “they never had any answers” — and when people told her this couldn’t happen, all she could think was, well, it did. After the diagnosis, Strayhorn stopped vaccinations with Cali and decided not to vaccinate her second daughter, Melia.

The CDC refutes claims that vaccines are causally linked to autism. But Strayhorn is absolutely convinced -- in part because she never felt doctors had provided her with explanations, and in light of her experience, she says she acted in the best interests of her children. The hyped but widely discredited “link” between vaccines and autism is questioned often enough that when “vaccines” is typed into an incognito Google search, the first two suggested phrases are “vaccines and autism” and “vaccines cause autism.”

“Everybody knows our stance” on vaccinations, Strayhorn said, and they know the reason for it, too. She hasn’t held awkward conversations with people about her decision not to vaccinate Cali and Melia, describing herself as fairly vocal about her stance and background, even putting out copies of parts of Cali’s medical records. “She was injured by the vaccination,” she insists.

Requesting Private Information

Asking about another child’s vaccinations is “a very awkward question to ask because you’re basically calling into question another parent’s parental choices,” David Lesser, a stay-at-home dad and writer, said. From there, the conversation can escalate quickly.

Lesser, who has a 2-year-old son and a 6-year-old daughter, recalled a chat among several other fathers where the majority were “on board” with vaccinations. But one was not as decidedly pro-vaccinations as the others, and the discussion turned into “more of a friendly debate” over minor details, and since that father did actually vaccinate his children, the debate never escalated. “But I wouldn’t be surprised if friendships were lost over this issue,” Lesser said.

Another child's vaccinations are not her business, said Dana Summerville, who owns and runs the Parties and Playdates Studio in Butler, Pennsylvania, a parent-child play center. She said she does not discriminate against unvaccinated children in her studio or ask if children have been vaccinated. Summerville merely hoped that if children weren’t vaccinated that they stuck around the vaccinated ones, and she made sure her own children had their shots.

Recently, parents have been asking an unprecedented number of questions about where to let their kids play and with whom, Karen Ernst, a leader of Voices for Vaccines, a group that advocates for vaccination as part of the Atlanta-based Task Force for Global Health, said. “Parents with babies who are too young to be vaccinated are really concerned, especially if they live in … places with measles outbreaks,” she said. They’re unlikely to schedule playdates with anyone unvaccinated, even going so far as to cancel them if they’re afraid of encountering one.

Ernst fell into vaccine advocacy through a scare of her own, when she brought her youngest, then a 10-day-old infant, to her second child’s birthday party. Afterward, she learned that one of the children there was unvaccinated and had chicken pox. “I wish I had bothered to ask, ‘Hey, is everyone vaccinated?’” she said. “It’s scary when you realize that your baby, whom you thought was protected by the social contract because everyone would be following the same rules, is not protected.”

Ernst said parents need to make sure not to scare or shame other parents about vaccinations when having the big talk. “Parents need to keep in mind that what they’re asking is not about a personal parenting choice,” Ernst said. “They’re not asking whether or not you breastfed your children. They’re asking in order to protect their own children.”