Writing for The Atlantic, Sarah Zhang analyzes how past and present vaccination campaigns in the United States have attempted to boost child vaccination rates—and why vaccine uptake among children has never been "immediately universal."

'Vaccine uptake in children has never been immediately universal'

According to Zhang, "[v]accine uptake in children has never been immediately universal—not for polio, not for measles, chickenpox, HPV, or any other childhood shot." For instance, in September 1957, two years after the polio vaccine became available, just 50% of children had been fully vaccinated against the disease.

According to a report from the National Foundation for Infantile Paralysis, now known as the March of Dimes, low vaccine uptake among children was not a result of supply issues, or doubts surrounding the vaccine's safety or efficacy. Rather, according to researchers, when the "initial excitement" surrounding the polio vaccine "faded," vaccine proponents had to find ways to reach the remaining unvaccinated Americans—an effort that took nearly two decades before polio was eradicated in the United States.

Similarly, before the Covid-19 pandemic, it typically took years for vaccines to go from receiving FDA approval to being mandated in schools to achieving high vaccination rates. 

How to boost vaccination rates among kids

To boost vaccination rates among children, a successful vaccination campaign must reach the parents who remain indifferent or hesitant, as well as those who might not have the time or easy access to doctors, Zhang writes.

In previous cases, a combination of persuasion and vaccine mandates has eventually managed to boost vaccination rates—but these tactics have their limits, Zhang writes. "No past vaccine is a perfect analogue for [Covid-19], but each illuminates the challenges of a task as gargantuan as trying to immunize every child in America," she explains.

For Covid-19 specifically, one issue could stem from the first year of the pandemic, when experts consistently reassured parents that Covid-19 was significantly less deadly for children—a perspective that has since turned Covid-19 vaccination efforts for children into an "uphill climb," Zhang writes.

"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-19]," Zhang writes.

For instance, in 1963, the first measles vaccine was approved, marking an inflection point in America's vaccination history, changing both the type of disease considered worth vaccinating against and the role of federal and state governments in immunization, according to Elena Conis, a historian of medicine at UC Berkeley.

During that time, measles was seen as a routine childhood illness—as "inevitable as 'wornout shoes' and scraped knees," according to a doctor Conis quoted. As a result, to persuade parents that their children needed to be vaccinated against measles, health officials in the 1960s launched vaccine campaigns that emphasized rare but severe complications, including ear infections, pneumonia, and swelling in the brain that could cause hearing loss or death. 

In response to these efforts, 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 noted. "Long lines and short hours in out-of-reach public health clinics did not help."

The situation created an uneven distribution of the measles vaccine among children until the 1970s, when measles outbreaks hit U.S. cities and public health officials began implementing state-regulated school vaccine mandates. "One of the justifications for making measles vaccines and other vaccines mandatory through school is it does have a kind of equalizing effect," said James Colgrove, a sociomedical-sciences professor at Columbia University.

By 1980, all 50 states had implemented measles-vaccine mandates. As a result, 96% of American schoolchildren had been vaccinated against measles in 1981.

"Historically," Conis said, "we've turned to mandates when voluntarism wasn't cutting it. But in recent years, we in some cases didn't wait for that."

Although vaccine mandates in schools have historically been a key policy in raising U.S. vaccination rates, Conis and other scholars noted that mandates often trigger tension between individual autonomy and the protection of the American public. "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. 

"Once you go down the mandate road, you're sort of making the persuasion road a little rockier," said Julie Downs, a psychologist and behavioral scientist at Carnegie Mellon University. "So maybe we do want to go down the persuasion road with kids a little bit before we get to the mandate mode." 

Ultimately, "[t]he viability of school mandates will also depend on how well the vaccines perform, especially in the long term," Zhang writes.

Notably, Covid-19 vaccines have been available to children under 16 for just a few months. During this time, roughly 26% of children ages 5 to 11 and 57% of teens ages 12 to 17 have gotten both shots. 

"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," Zhang writes. However, "in historical terms, we are still very, very early into our efforts to vaccinate against [Covid-19]." (Zhang, The Atlantic, 3/10)