In September 1957—two years after church bells rang in celebration of the new polio vaccine, two years after people rejoiced in the streets, two years after Americans began lining up for their shots—the proportion of children fully vaccinated against polio remained at about 50 percent.
Supply was not the problem. Nor were doubts about the vaccine’s safety or efficacy, concluded a report from around that time by the National Foundation for Infantile Paralysis, now known as the March of Dimes, which had funded research into the vaccine. But the “initial excitement” had nevertheless “faded,” and vaccine proponents found themselves in an incremental slog to reach the remaining unvaccinated Americans. Well into the 1960s, doctors held “Sabin Oral Sundays,” dispensing sugar cubes dosed with a drop of the oral vaccine invented by Albert Sabin. It would ultimately take more than two decades to go from ringing church bells to polio eradication in the U.S.
Today, with COVID vaccinations stalled and rates in children particularly low, the COVID vaccination campaign has drawn comparisons, usually unfavorable, to that for polio. But history has a way of flattening lengths of time. Vaccine uptake in children has never been immediately universal—not for polio, not for measles, chickenpox, HPV, or any other childhood shot. In the past, vaccines have routinely taken years to go from FDA approval to being mandated in schools to high vaccination rates. COVID vaccines, meanwhile, have been available for kids under 16 for mere months, and only under emergency use. In this time, the most enthusiastic have gotten their two shots, amounting to some 26 percent of children ages 5 to 11 and 57 percent of teens ages 12 to 17. These rates, which are so far below that of adults that they suggest many vaccinated parents aren’t vaccinating their kids yet, have already prompted much hand-wringing for being too low.
But every successful vaccination campaign has had to go beyond the most enthusiastic—to reach for the parents who are indifferent or hesitant, those who might not have the time or easy access to doctors. In the past, a combination of persuasion and mandates has eventually managed to accomplish this, but both tactics have their limits. Three historical examples—polio, measles, and HPV—are instructive here. No past vaccine is a perfect analogue for COVID, but each illuminates the challenges of a task as gargantuan as trying to immunize every child in America.
For more than a year after the coronavirus first appeared, experts sought to reassure parents that COVID is far less deadly for kids, and this message, some now argue, has turned vaccinating kids into an uphill climb. But convincing parents that a disease that is familiar, that they have seen many kids recover from, is in fact worth preventing is not at all unique to COVID.
With polio, this campaign of mass persuasion began while the vaccine was still under development. In 1938, President Franklin D. Roosevelt founded the National Foundation for Infantile Paralysis to combat polio, after his own suspected bout of the disease. The foundation’s massive and massively successful fundraising efforts elevated polio “from a relatively uncommon disease into the most feared affliction of its time,” the historian David Oshinsky writes in Polio: An American Story. “If you looked at polio, in terms of other dangerous childhood diseases, it ranks rather low in numbers,” Oshinsky told me. “But what the March of Dimes did, basically, was to turn this disease and the prevention of it into a national crusade. Having the president of the United States as a polio survivor certainly helped dramatically.” By the time a vaccine finally became available, in 1955, people who had donated dimes over the years were invested in the vaccine’s success. They were ready for it. The church bells were ready too.
But this message about polio’s danger could go only so far, as the foundation’s report a few years later lamented. In its survey of public acceptance of the polio vaccine, the report found a pattern that would prove recurrent: The unvaccinated were less likely to be wealthy, to be highly educated, or to see their doctors regularly. Other reports noted that white people were also more likely to be vaccinated than those who were nonwhite. Polio cases fell markedly as the vaccine rolled out, but when outbreaks did happen, they clustered in poor, urban neighborhoods of color, says Elena Conis, a historian of medicine at UC Berkeley and the author of Vaccine Nation: America’s Changing Relationship With Immunization. In 1963, the head of the CDC declared racial disparities in vaccination a “blot” on the nation’s record.
Also in 1963, the first measles vaccine was approved. That vaccine was an inflection point in America’s vaccination history, Conis argues, changing both the type of disease considered worth vaccinating against and the role of federal and state governments in immunization. If polio struck fear in the hearts of parents, measles did not. Measles was seen as a routine childhood illness—as “inevitable as ‘wornout shoes’ and scraped knees,” according to one doctor Conis quotes. About one to four in every 10,000 children who got measles died, which was dramatically less deadly than other diseases parents knew to vaccinate against in the ’60s, such as smallpox or diphtheria, but still more than 100 times deadlier than chickenpox. “Even though people in the 1950s and ’60s thought measles was no big deal,” Conis says, “I think if people had to see their kids through today, they would think it’s a big deal.” Measles is “mild relative to stuff we can’t fathom.” Historically, Americans accepted far more illness and death in children than we’re used to today—a shift caused in no small part by the success of childhood vaccinations.
[Read: Why a three-dose vaccine for young kids might actually work]
To persuade parents to vaccinate their kids against measles in the 1960s, though, public-health officials began emphasizing rare but severe complications: ear infections, pneumonia, and swelling in the brain that could lead to deafness or even death. One ad campaign featured a 10-year-old girl named Kim who had become partially deaf and mentally impaired after a measles infection. This worked, to a certain extent. Measles cases fell after the vaccine became available, but the disease persisted, once again, in poorer, nonwhite neighborhoods with lower vaccination rates. Parents in “the middle class and upper class were easily persuaded that measles was worth preventing, but those living in poverty spoke of more pressing priorities,” Conis writes. “Long lines and short hours in out-of-reach public health clinics did not help.” In short, the U.S. didn’t learn the lessons from polio vaccination, she told me. The “same exact pattern” of uneven vaccine uptake took hold with measles.
Inconsistent funding for vaccination stymied efforts too. In 1962, emboldened by the success of the polio vaccine, President John F. Kennedy signed the Vaccination Assistance Act, allocating federal money for immunization efforts, which were previously seen as largely state and local responsibilities. But that funding lapsed under Nixon in the 1970s, and measles also resurged. Later, the Carter and Clinton administrations would expand the federal government’s role in vaccination; today, it both purchases vaccine doses and sets the recommendations for who should get them.
Faced with measles outbreaks in cities in the ’70s, though, public-health officials began utilizing another tool that remains in place to this day: mandates in schools, which are set state by state. “One of the justifications for making measles vaccines and other vaccines mandatory through school is it does have a kind of equalizing effect,” says James Colgrove, a sociomedical-sciences professor at Columbia. (School mandates existed for polio and other earlier vaccines, but they were patchwork and largely not enforced.) And this did work to raise vaccination rates dramatically. By 1980, all 50 states had measles-vaccine mandates in place. The year after that, 96 percent of American schoolchildren had been vaccinated for measles. As more and more vaccines were approved in the U.S., they were added piecewise to state immunization requirements. This process generally took years; the chickenpox vaccine, which became available in 1995, was not required in schools in any state. until 1998, and only reached all 50 in 2015.
Jumping quickly to mandates has backfired before. In 2006, Merck’s vaccine for the human papillomavirus, or HPV, won FDA approval, and the company immediately embarked on a state-by-state campaign to pass bills adding it to the list of mandated vaccines for school. The effort failed spectacularly.
HPV is a virus that can cause cancer, but it was by no means a well-known one. As Merck tried to promote its vaccine, it instead became consumed in the culture wars over teenage sexuality. Opponents argued that school mandates were inappropriate because the sexually transmitted virus doesn’t spread in classrooms like airborne or gastrointestinal viruses do. This kind of mandate wouldn’t have been unprecedented, though, because the vaccine for hepatitis B, which can also be sexually transmitted, was already routinely required for schools. But the HPV vaccine drew far more attention because it was also the first vaccine ever approved only for girls. (Years after this initial controversy, the vaccine was later approved for boys and men to prevent genital warts and anal cancer.) Moreover, adding vaccines to the school immunization list was usually a quiet bureaucratic process overseen by state health boards. Merck’s strategy, of lobbying for laws in state legislatures, was more aggressive, and it turned the process into an intensely political one where politicians were explicitly asked to weigh in. “Merck’s role in all of that ended up muddying the waters,” Colgrove says. To this day, the HPV vaccine is required in only three states plus D.C., and as a result, only half of eligible teens have gotten all of their shots—even though the HPV vaccine is about as effective and durable as vaccines get.
“Historically,” Conis told me, “we’ve turned to mandates when voluntarism wasn’t cutting it. But in recent years, we in some cases didn’t wait for that.” The HPV vaccine is a stark example. Mandating vaccines in schools has been a key policy in raising U.S. vaccination rates, but as Conis and other scholars have noted, mandates do contain a tension between respecting individual autonomy and protecting the public. The U.S. as a whole tends to mandate more vaccines than other Western countries, and the number has doubled since the ’90s. “We entered this century with a longer list of mandatory vaccines for kids than we ever had before. To me, it’s not at all surprising that that saw a rise in vaccine hesitancy and skepticism in the face of this. It’s possible we used up a lot of goodwill in doing that,” Conis said. By the time COVID arrived, had we used up too much to immediately mandate one more?
Not only have no states mandated the current emergency-use COVID vaccines for schoolchildren, but 17 have already banned schools from requiring it. (A handful will require the vaccine when it is fully approved by the FDA for children.) Experts worry that pushback against COVID vaccination could, in some cases, turn into a pushback against all childhood vaccinations. “A handful of years ago, there was no strong correlation between political ideology and vaccine hesitancy,” Asheley Landrum, a psychologist at Texas Tech University who studies science communication, told me. Now “vaccination in general and childhood vaccination in particular has become really entangled with people’s political identity.”
Still, political polarization doesn’t entirely account for the low COVID vaccination rates in children. A good number of parents whose kids are unvaccinated are not opposed: They are planning to vaccinate their kids, or they want to wait and see. And while mandates can work, they can also push people away. “Once you go down the mandate road, you’re sort of making the persuasion road a little rockier,” says Julie Downs, a psychologist and behavioral scientist at Carnegie Mellon. “So maybe we do want to go down the persuasion road with kids a little bit before we get to the mandate mode.” Perhaps, in time, as COVID fades from the headlines, Landrum told me, vaccines might not provoke the same strong feelings. They might become less politicized, less partisan, and more routine.
The viability of school mandates will also depend on how well the vaccines perform, especially in the long term. As my colleague Rachel Gutman has noted, the flu actually kills more kids every year than many diseases for which vaccines are mandated. But no states currently require the flu shot, because although schools track vaccines when kids start elementary or middle school, they don’t have a way of tracking shots for every kid every single year. If COVID vaccines are needed annually, they’ll be a lot harder to slot into the current vaccine-requirement system. But whether they will be needed so frequently is, as yet, still unclear. It hardly feels this way living through it, but in historical terms, we are still very, very early into our efforts to vaccinate against COVID.
