By Marie Rosenthal, MS

The U.S. public health laws that require vaccination before entering school have prevented considerable pediatric morbidity and mortality, and yet, they are being eroded, according to public health experts and pediatricians.

In 1981, all 50 states had vaccine mandates for school entry with few exceptions. As of 2019, all 50 states still required some vaccination for school entry, but not necessarily all the CDC-recommended childhood vaccines. However, 29 allowed medical or religious exemptions; 17 allowed medical, religious or “philosophical” exemptions; and some did not require vaccination for homeschooled children, according to the latest report by the CDC’s Public Health Law Program (bit.ly/4amqKmk-IDSE). In addition, the documentation required to obtain an exemption varied by state.

These exemptions mean more parents can send their unvaccinated children to day care or school, endangering people in their communities.

Measles is one of the first diseases that start appearing when vaccination rates go down, according to Paul Offit, MD, the director of the Vaccine Education Center and an attending physician in the Division of Infectious Diseases at Children’s Hospital of Philadelphia. “Measles is the canary in the coal mine because it is that contagious,” Dr. Offit told Infectious Disease Special Edition. “It has a contagiousness index of 18 R0 compared with COVID-19 or flu, which has a 2 to 4 R0.”

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Herd immunity must be above 95% to prevent measles, and having a growing number of unimmunized children increases the risk for measles outbreaks. It’s that simple, experts explained.

“In the U.S., for the 2022-2023 school year, our rate for measles vaccine coverage for kindergartners is only 92%,” explained Sarah Lim, MBBCh, a medical specialist at the Minnesota Department of Health. “Now, those numbers sound high, but measles is so contagious, vaccination rates need to be 95% or higher to contain transmission.

“And it’s not enough to have a high national coverage rate,” Dr. Lim added. “Every state and every community need that high level, and that is not happening. For example, in my state of Minnesota, only 87% of kindergartners are fully vaccinated, and we have pockets of communities and schools where the rates are even lower,” she said at a press briefing about measles, sponsored by the Infectious Diseases Society of America (IDSA).

Brief History Lesson

Before the measles vaccine was approved in the 1960s, 3 million to 4 million cases of measles, mostly among children, were reported every year in the United States. “There were roughly 48,000 hospitalizations and 500 deaths, and when children died, they died of pneumonia, dehydration or encephalitis,” Dr. Offit said.

“School mandates are the key to the measles story,” he added. The journey to elimination “showed the power of school mandates.”

By the 1970s, about 40 states had school vaccination mandates. By 1981, after several large outbreaks, all 50 states had school mandates, which required children to receive one dose of measles-mumps-rubella (MMR) vaccine.

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a As of March 28, 2024
Source: CDC

Between 1989 and 1991, there was a large measles outbreak; 11,000 people were hospitalized, and 166 people died from measles complications. This led to the recommendation for a second dose given between 4 and 6 years of age, which again was required for school entry.

And by 2000, the United States eliminated measles from this country—an amazing achievement.

“This is arguably the most contagious infectious disease, and we eliminated it because we had herd immunity at a greater than 95% level either from vaccination or natural infection,” Dr. Offit said.

However, measles vaccination took a hit in 1998 when Andrew Wakefield published a paper—which other researchers have refuted many times—claiming the MMR vaccine caused autism (see sidebar). His paper, which was published in The Lancet, was retracted in 2010, and Mr. Wakefield lost his medical license over misconduct related to the study. A fitness to practice panel found he performed unnecessary and invasive tests on children without permission from a review board and did not report study funding from MMR litigants.

“Now, that paper was wrong,” Dr. Offit said. “Studies showed it was wrong; nonetheless, it scared parents, and you started to see an erosion in vaccine rates. Whenever you see even a mild fraying of vaccine rates, measles is always the first one to come back.” (The Autism Science Foundation has a resource page for providers and parents that explains the science of autism and discusses vaccination: bit.ly/3vGFuxf-IDSE.)

Although that happened more than 25 years ago, Mr. Wakefield and anti-vaxxers are still touting misinformation about the measles vaccine. “It’s hard to un-ring the bell,” Dr. Offit said. “I think once you’ve scared people, it’s hard to un-scare them.”

A Modern-Day Primer: Fighting Bad Information With Good Science

Misinformation and disinformation about medicine, particularly aimed at vaccinations, have been circulating since Edward Jenner developed the first vaccine against smallpox in 1796. Since he used cowpox for the inoculation, anti-vaxxers said it would turn people into cows.

It’s easy to smile at the scientific ignorance of people in the 18th century, but is it that far removed from thinking the COVID-19 vaccination campaign is enabling Bill Gates to inject people with microchips?

These campaigns have been “on steroids” since COVID-19, according to Paul Offit, MD, of Children’s Hospital of Philadelphia.

“With the COVID mandates, we leaned into a libertarian left hook, and you started seeing a lot of legislation pushing back on vaccine mandates, including school mandates,” he explained.

And this has affected people’s beliefs about all vaccinations. Coverage of kindergartners with all required vaccines has declined 2% from 95% in 2019-2020 to 93% in 2022-2023, according to the CDC. In addition, the exemptions to school mandates increased in 41 states, the agency said.

Although this is still a high number of vaccinated children, rates of the measles-mumps-rubella vaccine must reach 95% to stop transmission; 93% coverage leaves about 250,000 children unprotected against measles.

Vaccines are one of the most common topics on social media for misinformation and disinformation, agreed Joshua Barocas, MD, of the University of Colorado Anschutz Medical Campus, in Aurora, who added that it was important for public health officials to advocate for the evidence.

“Our job as infectious disease physicians and public health officials is to advocate for what works based on the best science and the best evidence,” Dr. Barocas said. “We have decades of safety data [about vaccines].”

Dr. Offit agreed that “you need the science. When Joseph Ladapo [the surgeon general of Florida] says the mRNA vaccines are contaminated with DNA fragments, and Robert Malone, who is an MD, gets up in front of Congress and says the same thing, what do you do?”

You give the facts, Dr. Offit said, but you explain them in layman’s terms. “Not everybody has to understand exactly how DNA fragments work, but they need to know they won’t enter your DNA. When you eat food—assuming you eat anything made from plants or animals—DNA will be absorbed into your circulation, but it cannot insert itself into your DNA. It never gets past the cytoplasm.”

When Andrew Wakefield falsely blamed autism on MMR vaccination, the Autism Science Foundation surveyed parents of children with autism—90% said it was possible MMR caused autism. “Now with 18 studies done in seven countries on three continents involving hundreds of thousands of children and costing tens of millions of dollars, if you ask the same question, that 90% number is down to 15%,” Dr. Offit said. “So, science does make a difference.”

However, it takes a “tremendous amount of effort on a community level, on an individual level to counteract that misinformation,” admitted Sarah Lim, MBBCh, a medical specialist at the Minnesota Department of Health.

Dr. Offit knows only too well the personal toll of trying to help people distinguish between bad information and facts when discussing vaccination. He has had three death threats that the FBI called legitimate, and he has been told he is on a death list of 100 American Jews.

“People may attack my science, which is fine, because that is how science gets better,” he said. “But the minute you take on the anti-vaccine groups by name, it is not science anymore. It is politics, and politics is mean; it’s personal and it’s ugly.

“I think it was the Hyman Roth character in ‘The Godfather II’ who said, ‘This is the business you’ve chosen.’ I’ve made that choice [to speak out against the disinformation].

“I don’t like to see children come into our hospital with a vaccine-preventable disease because their parents had bad information. They suffer, and they occasionally die. That is always in my head,” he added. “You have to put the information out there the best you can knowing you are trying to stop Hurricane Katrina with a plastic cup, but that’s all we have.”

An interesting report about the anti-vax movement is available here: https://counterhate.com/research/the-disinformation-dozen/.

—Marie Rosenthal, MS

That intransigence can be explained, at least in part, by “the null hypothesis,” Dr. Offit noted. “You can never accept the null hypothesis; you can never prove never,” he said. “That is the way the lawyers grill you on depositions: ‘Can you say that it can’t do that?’ And you can only say that one thing is associated with another at a certain level of statistical power.

“But MMR does not cause autism even though, technically, the scientific method doesn’t allow you to say that,” he said.

Time Out

“The second big hit was COVID,” Dr. Offit said.

With more children attending school virtually, fewer children received their routine immunizations. In addition, misinformation and disinformation, much of it about the mRNA technology used in the new COVID-19 vaccines, which caused a high level of distrust of the government, the pharmaceutical industry, medical professionals, journalists and public health were rampant during the pandemic. In fact, 21 states have banned a COVID-19 vaccination requirement for school entry, according to the National Academy for State Health Policy (bit.ly/3xpbZR9-IDSE).

“Misinformation and disinformation were always around,” Dr. Offit said, “but they just went on steroids during COVID.”

Joshua Barocas, MD, an associate professor of medicine at the University of Colorado Anschutz Medical Campus, in Aurora, agreed that misinformation surrounding vaccinations is a significant problem—one that public health officials can address by advocating for the evidence about what works best.

“We have seen decades of safety data, and there is no reason to believe that vaccines are anything but helpful when it comes to preventing measles,” Dr. Barocas said during the IDSA media briefing.

Unfortunately, that distrust, particularly of the COVID-19 vaccines, spread to other vaccines. Globally, more than 61 million doses of measles-containing vaccine were postponed or missed from 2020 to 2022 because of COVID-19. These missed opportunities increase the risk for international outbreaks, including in the United States, according to the World Health Organization.

“We’re seeing an increase in measles globally, primarily because of declining vaccination rates due to the disruption of the COVID pandemic,” Dr. Lim said. “The World Health Organization has reported that in 2022, only 83% of children had received a dose of measles vaccine by their first birthday. That is the lowest since 2009.”

An estimated 128,000 people died from measles in 2021 alone, according to the WHO. Most cases were among children younger than 5 years.

Considering the rise in measles cases globally, the risk for importations is almost unavoidable, and as of April 11, 2024, 121 cases were reported by 18 U.S. jurisdictions: Arizona, California, Florida, Georgia, Illinois, Indiana, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York City, New York state, Ohio, Pennsylvania, Virginia and Washington. Sixty-five patients were hospitalized, according to the CDC. Most of the cases and hospitalizations were among children younger than 5 years.

Although the vaccination status of 24% of the cases are unknown, 59% of the cases were unvaccinated and 12% only received one dose of the MMR vaccine. Only 5% of people, who were all older than 20 years, received two doses of MMR.

There have been seven outbreaks (defined as at least three related cases) reported in 2024, and 72% of cases (70/97) are outbreak associated. For comparison, four outbreaks were reported during 2023 and 48% of cases (28/58) were outbreak associated.

As this outbreak plays out, it is important for all healthcare workers to be prepared, Dr. Lim said. They should make sure they know how to diagnose measles—it has been so rare that most younger staff have no idea what measles looks like—and talk to parents about assuring their children catch up on not only measles but all their routine childhood immunizations, she said.

“It’s important to identify cases as soon as possible because of that risk for exposure,” Dr. Lim said. This is essential in a hospital where there are so many vulnerable and immunocompromised people.

The crux of the matter is that the United States and countries around the world need to get caught up on their measles vaccinations, Dr. Barocas added.

“We have to get this message across that all of the current and long-standing data say that MMR vaccine has been tested for safety and efficacy,” he said. “These are not only efficacious at preventing disease, but they are incredibly safe. Vaccines can improve the health of not just your community, but also reduce the burden on your family.”

This article is from the April 2024 print issue.