Less than two decades ago, the American medical system could make an impressive boast: it had eradicated measles in the U.S.
By 2000, while some other countries were losing thousands of children to measles-related deaths, the U.S. was experiencing fewer than 100 cases per year and no deaths. Virtually all domestic measles cases originated with travelers from abroad.
It was no small achievement. Far from the mild disease that some adults think they remember from childhood, measles in the mid-20th Century used to kill 400 or 500 American children every year and cause thousands of cases of encephalitis with lasting consequences, like deafness and mental disability.
The introduction of a safe, highly effective vaccine in 1963 led to a sharp decline in cases, which once numbered 3 or 4 million per year in this country alone.
Today, however, measles is on the upswing, with more than 700 U.S. cases in the U.S. so far this year. That’s the largest number in a quarter century.
To many medical experts, the trends are ominous, not solely because of the present surge in cases, but especially because so many American children are either unvaccinated or under-vaccinated.
The U.S. appears to be a fertile ground for a return to the epidemics of the past.
A recent United Nations Children’s Emergency Fund survey found that the U.S. had 2.6 million unvaccinated children, the largest number of any high income country.
Last week, an article in the online medical newsletter STAT compared the situation to tinder that needs only a spark to ignite it.
That spark would be the exceptional ability of measles to spread. Measles can infect an estimated 90 percent of a non-immune population, medical experts advise.
The tinder-and-fire metaphor also occurs to David Witt, a Kaiser Permanente epidemiologist.
Working in Kaiser’s Northern California region, Witt worries about schools with a high percentage of children who have little or no immunity because they or their parents are vaccine “denialists.”
Medically speaking, this group of kids is the tinder ready to be ignited.
When a student from one of these schools returns from a trip abroad, having visited a country like France, Israel or India that is now suffering a major measles outbreak, they bring the disease “to a group that is highly likely to get it,” Witt said.
“Because it’s contagious four days before the rash (appears to signals its presence), it’s a really sneaky virus…(It) spreads before you are sure it’s measles.”
A child with measles may infect an extraordinary 9 to 18 others if they lack immunity, according to an article in last month’s New England Journal of Medicine.
For comparison, someone with influenza typically infects one or two others.
Witt points out that the measles vaccine is easy to obtain and has been shown again and again to be safe and highly effective.
As an infectious disease expert, he would like to see 100 percent of the population vaccinated, excepting only those with a genuine medical reason not to be vaccinated, like a child in cancer therapy.
He cites the ironic example of a child who has survived leukemia and should be able to go to school, but can’t because of the measles risk from other children who refuse to be vaccinated.
Witt’s personal experience includes providing medical help in Indonesia following the catastrophic 2004 tsunami, which killed 170,000 in the province of Aceh alone.
The first medical priority was to provide clean drinking water for the many survivors crammed into inland camps and shelters, he said.
Then a measles case appeared. The highest priority became the provision of hundreds of thousands of measles vaccinations to prevent the disastrous epidemic that could rage through an already vulnerable population under post-tsunami conditions of extreme crowding, malnutrition and stress.
Mortality and Brain Damage
Mortality can rise to 10 percent under such conditions, where there is little if any ability to treat the pneumonias and other complications that would inevitably arise from a measles epidemic, Witt said.
In healthy populations, mortality from measles is far lower, commonly cited as one or two in a thousand cases. That number can be disputed as an artifact of the pre-vaccine era, when perhaps a tenth of cases were reported to public health authorities.
If the deaths were recorded correctly, there would be 10 times as many cases of death from an unhealthy population as from a healthy one, where only one or two deaths per 10,000 cases take place.
Regardless of the actual mortality rate decades ago, history is clear that measles brought with it hundreds of deaths and thousands of disabled children at a time when the U.S. population was half of today’s, and nearly every child got the disease.
Now that there is a safe, inexpensive, effective vaccine, it makes no sense to risk these tragedies, in the view of Witt and many others.
Witt sees it in moral as well as medical terms.
“The most horrible thing parents can undergo is their responsibility for their child suffering something catastrophic”, like allowing lifelong disability or death from a readily preventable disease, he said.
The problem is not confined to the United States, of course. The New England Journal of Medicine reports that Europe experienced three times as many measles cases in 2018 as in 2017, and 15 times as many as in 2016.
The rise of measles worldwide makes it all the more important for the U.S. to put its vaccination house in order to protect its children, epidemiologists say.
As an infectious disease expert, Witt is naturally concerned about more than measles. He identifies diphtheria and tetanus as two other killers in the same category – namely, deadly but easily preventable with safe, effective vaccines.
Parents should be certain that their children have had two measles vaccinations, which create at least 97 percent immunity. (That means 97 of every 100 who receive the two vaccinations become immune.)
A single vaccination is thought to provide about 90 percent immunity, not a bad level for some diseases, but not enough to stop the spread of super-infectious measles when people mingle with one another as they do in schools and crowded urban environments.
Adults born before 1957 can assume they are immune because they grew up in a time when no vaccine was available and must have caught measles, conferring lifetime immunity.
Adults born between 1957 and 1989 need to check their immunization records. They may have received only a single immunization, as recommended until 1989.
Adults who can’t find their records or who simply want to be sure of their vulnerability to measles – for example, grandparents around small children – can learn by scheduling a simple and reliable blood test, according to Kaiser epidemiologist Witt.