U.S. health officials say that between January and March, 387 cases of measles have been reported in 15 states, exceeding the count for all of last year. In 2018, 372 cases were reported, according to the Centers for Disease Control and Prevention.
Public health authorities worry about outbreaks in communities where vaccination rates are low, fueled by a growing movement of people who view the MMR vaccine for measles, mumps and rubella as dangerous. The measles component of the vaccine has been in widespread use since the 1960s, and medical experts say the MMR vaccine is safe and highly effective.
“We have growing pockets of susceptibility,” said epidemiologist Arthur Reingold of the University of California, Berkeley, School of Public Health, as the virus is carried from regions where measles is more widespread. “When we do have someone travel from New York to Israel or from Europe to Disneyland or whatever you envision, we have the opportunity for much larger outbreaks.”
Measles deaths declined worldwide from 550,000 in 2000 to 110,000 in 2017. Public health officials say the vaccine is the reason. The World Health Organization says measles immunizations prevented 21 million deaths between 2000 and 2017.
The organization says more than 95 percent of such deaths occur in countries with low per capita incomes and poor health infrastructure.
In 2017, however, 20 million infants did not receive at least one of the recommended two doses of the measles vaccine, putting their communities at risk. India, Pakistan and Nigeria are among the countries with large concentrations of unvaccinated children.
In the United States, where the inoculations are widely available, anti-vaccine sentiment has led to children at risk of contracting measles. The disease was declared eliminated in the U.S. in 2000.
The anti-vaccine movement gained momentum when a 1998 study — which was later retracted — linked autism, a developmental disability, to the MMR vaccine that inoculates against measles, mumps and rubella.
Repeated studies have shown no link between vaccines and autism, says infectious disease expert Peter Hotez of the Baylor College of Medicine in Texas.
“The scientific community responded with studies involving hundreds of thousands of children,” he said. “And we’ve clearly shown that children who get the MMR vaccine are no more likely to get autism than children who don’t.” He added that children with autism were no more likely to have received the vaccine than those without the condition.
This issue is personal for Hotez, whose grown daughter has autism. He has laid out his evidence in the book "Vaccines Did Not Cause Rachel’s Autism."
Critics are unconvinced. “Nobody can scientifically say whether the MMR is actually causing more harm than measles, mumps and rubella,” maintains Robert F. Kennedy Jr., an activist attorney. “The reason for that is, like other vaccines,” he said, “it’s not required to be safety tested.”
It is true that vaccines have not been subjected to double-blind tests, medical experts say, tracking children who have received the vaccine against others who have not, with parents unaware of which children were vaccinated. The experts say that in the United States, measles typically kills one in 1,000 who contract it, and mortality is far higher in the developing world, so a controlled trial would put many children at risk.
Major medical groups and public health agencies agree, says epidemiologist Arthur Reingold.
The "CDC (Centers for Disease Control and Prevention) or ACIP (Advisory Committee on Immunization Practices), WHO or the American Academy of Pediatrics are all in total agreement about the benefits of vaccination against measles and other diseases radically outweighing any conceivable risks,” he said.
The CDC says that study after study has verified the safety of the measles vaccine, and that the risk of severe allergic reaction is one in a million.
Growing numbers of unvaccinated children have given measles a foothold in the United States and Europe, however. Vulnerable communities include tightly knit or isolated groups, for example, of the Amish in Ohio, Orthodox Jews in New York, and eastern European immigrants in Washington State.
California, Mississippi and West Virginia have responded by refusing exemptions from vaccination, except for medical reasons. Forty-seven states allow broader exemptions.
“Of those 47,” Hotez said, “there are 18 that also allow non-medical exemptions for reasons of personal or philosophical belief, and that’s where the battleground is.”
He says misinformation about vaccine safety is spread on the web and through books sold on Amazon, while medical experts face more difficulty in having their message heard.
“We’re looking at over 500 anti-vaccine websites that are out there,” he said, adding that each of them is "amplified on Facebook and other forms of social media.”
Hotez says vaccine opponents tailor their message by region.
“So with Texas, they see the soft underbelly being the far political right, the Tea Party, and they use Tea Party language,” he said. “Up in the Pacific Northwest, in Washington State or Oregon, they might use language of the far left.”
Kennedy says the CDC works hand in hand with the industry and hides the risks.
“The parents should know more about what’s good for that child than corrupted regulatory agencies and big pharmaceutical companies,” he said.
Medical experts worldwide say the MMR vaccine is essential for public health because measles is highly contagious and potentially deadly, and one infected person may infect three others.
“Then, each of those three people might infect three other people,” said Arthur Reingold. "And then another generation after that. Each of those people might infect some other people, and we could end up having sustained transmission.”
Health experts say that could bring a return to conditions of decades ago, when measles killed millions of children each year around the world.