As of Friday, there were 214 confirmed measles cases in New York's Rockland County, and every day my wife goes to work here, we worry that she will soon acquire the measles, too.

Opinion: My Wife Is One More Reason to Have Your Kids Vaccinated

Some people lack the ability to develop measles antibodies after vaccination. My wife may be one of them.

For a disease that was considered eliminated in the United States 19 years ago, measles sure isn’t very accepting of defeat. An outbreak in 2014 peaked at 667 reported cases in the U.S. before being subdued. As of May 3, the U.S. Centers for Disease Control and Prevention (CDC) had tallied 764 cases. The World Health Organization (WHO), the agency said in a release late last month, has tracked a 300 percent increase in measles cases globally compared to the first three months of last year.

The reason? Rising numbers of people refusing to vaccinate their children. My wife and I know this well. We live near, and both work in, one of the primary North American outbreak areas, New York’s suburban Rockland County. Here, a sizable contingent of ultra-Orthodox Jewish residents maintain a strong, sometimes religious-based resistance to vaccines. As of Friday, there were 214 confirmed cases here, and every day my wife goes to work — she’s the office manager at a dental clinic in Monsey, New York — we live in fear that she will soon acquire the measles, too.

You see, it’s not just young children that public health officials are trying to protect by encouraging everyone to be vaccinated. It’s also not simply those who are old or already ill, and whose immune systems can’t tolerate the vaccine, who need the rest of us to get vaccinated and prevent the disease from spreading. There are those among us who, for whatever reason, do not develop the antibodies from the standard measles, mumps, and rubella (MMR) vaccine.

My wife may be one of those.

She was vaccinated as a child, of course, and thought everything was fine until she took a job at a hospital about seven years ago. They required a measles “titer” test, which checks for evidence of those specific antibodies in the blood stream. She came up negative, she recalls, and was administered another vaccination. Two months later, she says, there was barely anything there, and the nurse in charge told her any further doses would likely be just as pointless.

Just why this happens in some people today is unclear, though in the early days of measles vaccination, before the “mumps” and “rubella” portions were added, it was easier to understand. James Cherry, a distinguished research professor at UCLA’s David Geffen School of Medicine and the Mattel Children’s Hospital Division of Infectious Diseases, was involved in vaccine research in the 1970s. He noted that, back then, improper storage was part of the reason for an average 10 percent failure rate in the vaccine. Some hospitals, Cherry told me, kept the measles vaccines in the doors of refrigerators, instead of deeper in, so they were subject to continual thawing and re-cooling.

Another issue, strangely enough, was vaccinating too early. Prior to the introduction of the measles vaccine in 1963, many mothers in the U.S. would have had the measles themselves. Their very young children, under 1 year old, would have been conferred passive acquired immunity, meaning some of the measles antibodies that mothers had developed were transferred to their children, albeit only temporarily. Still, the presence of mom’s antibodies prevented the formation of the child’s own antibodies if they were vaccinated too early, so some of those youngsters grew up without immunity, even though they received the shot.

Today, though, very few mothers have been infected with measles themselves, so vaccines are given earlier again — and for the MMR, that means a first dose between 12 and 15 months of age, and a second between ages four and six. According to the CDC, measles antibodies develop in approximately 95 percent of children vaccinated at 12 months. That number increases to 98 percent in children vaccinated at 15 months. Add in the second shot for older kids, and the percentage of recipients considered developing sufficient antibodies to fend off the measles hits 99 percent.

But that still begs the question: What’s going on with the roughly 1 percent of folks like my wife?

There are a few possibilities, Cherry says. It could be the case that my wife does in fact have antibodies, but that they’re just not detected in lab tests. If she were to get measles, he posits, she would likely get a milder, modified form and have a minimal chance of the spreading the disease. Or she could be lacking circulating antibodies, but still be protected by memory cells that would activate upon infection.

Still, there is also the possibility that the vaccine just doesn’t work for her. “The mechanism isn’t clear,” Cherry says, but we know that different people have different responses. Some people may produce four times as many measles antibodies as usual, and some might not produce many at all. In short, biology is complicated.

Whatever the case may be, measles remains a far cry from an innocuous disease — despite the protestations of vaccine opponents, who often argue that measles is, at worst, a mere annoyance, and that its severity does not warrant mandatory vaccinations. Before the development of the vaccine, measles killed roughly 2.6 million people around the globe every year, according to the WHO. By 2017, that number had been reduced to 110,000 — most of them children under the age of 5.

Beyond this, there’s also a phenomenon called “immune amnesia,” which makes young children more susceptible to other potentially deadly diseases for as long as three years after having had measles.

The truth is, my wife would almost certainly survive the measles if she did get it. But as a public health worker herself, she abhors the idea of her body being a potential safe harbor for the virus. No one has told her to stay home from work yet, but the thought of being pro-science and pro-vaccine, while still being potentially vulnerable to one of the most contagious and preventable diseases on Earth, is an unsettling and frightening one for her.

It is for both of us.

“Herd immunity is particularly important,” Cherry says. Measles is so virulent that 95 percent of a population needs to be immune to keep the vulnerable among us safer, making the spread of misinformation about vaccine safety a very real public health danger.

While it may often seem like nothing will change some people’s minds, Cherry still thinks framing the argument for vaccines around the health and safety — and in some cases, the very lives — of the young, the ill, and those who can’t be vaccinated is important. In that sense, the issue is not just about the threat of fines or the exercise of personal or religious freedoms. Whatever the case may be for my wife, we need people to understand the responsibility that we all have to those among us of any age who simply cannot be made immune to measles.

“Those people,” Cherry says, “you have to protect.”

Russ Dobler is a geophysicist, journalist, and the president of the New York City Skeptics, an all-volunteer nonprofit that promotes critical thinking and science education. He is also a regular columnist for the Committee for Skeptical Inquiry and the Center for Inquiry, and the science editor of the pop culture website AiPT! Comics.