After measles outbreaks, officials are becoming wary of new threats
Measles, a highly contagious but preventable disease, is reemerging in parts of the United States, a warning of the dangers of the strengthening anti-vaccine movement.
The Centers for Disease Control and Prevention has recorded more cases this year than the 58 in all of 2023, although the agency is not expected to release the exact numbers until Friday. On Monday, the agency advised health care providers to ensure unvaccinated patients, especially those traveling internationally, stay up to date on their vaccinations.
Cases will likely continue to rise because of a sharp spike in measles worldwide, along with spring travel to some regions with outbreaks, including Britain, said Dr. Manisha Patel, chief physician at the CDC’s division of respiratory diseases.
Nearly all cases so far in the United States have involved unvaccinated travelers. “We’re not going to see widespread cases of measles across the country,” said Dr. Patel. “But we do expect that more cases and outbreaks will occur.”
Measles is among the most contagious diseases; each infected person can spread the virus to as many as 18 others. The virus spreads through the air and can linger in the air for up to two hours after an infected person leaves the room, spreading quickly through homes, schools and childcare facilities.
In Chicago, one case of measles has occurred in a migrant shelter grown to 13, prompting the CDC to send a team to help contain the outbreak. (Two additional cases in the city appear to be unrelated.)
In Florida, seven students at an elementary school contracted measles, while the state’s surgeon general, Dr. Joseph Ladapo, left it up to parents to decide whether unvaccinated children could attend school.
In southwestern Washington, officials identified measles in six unvaccinated adult members of a family living in two counties. And in Arizona, an international traveler infected with measles dined at a restaurant and transmitted the virus at least two others.
Measles was eradicated from the United States in 2000, and American children generally must be vaccinated to attend school. Still, sporadic cases lead to larger outbreaks every few years. But with vaccination rates falling, exacerbated by the coronavirus pandemic, experts worry about a resurgence.
When vaccinations are not given, “the first disease that appears is measles, because it is highly contagious,” says Dr. Saad Omer, dean of the O’Donnell School of Public Health at UT Southwestern in Dallas.
According to the CDC, nine out of 10 unvaccinated people who come into close contact with a measles patient will become infected
Measles is much less fatal in countries with high vaccination rates and good medical care. Fewer than three in a thousand American children with measles will die from serious complications such as pneumonia or encephalitis, the swelling of the brain.
Roughly anyway one in five people with measles can end up in a hospital.
Because widespread outbreaks of measles are rare, most Americans, including doctors, may not recognize the vibrant red rash that accompanies respiratory symptoms with a measles infection. They may have forgotten the impact of the disease on individuals and communities.
“Most people in our local health department have never seen an outbreak of measles,” said Dr. Christine Hahn, Idaho’s state epidemiologist, who counted a small cluster of cases last year.
“It will be a big challenge for us to respond if and when we have our next outbreak,” she said.
Before the first measles vaccine was introduced in the 1960s, the disease was estimated to kill people 2.6 million people worldwide every year. But its overall impact could have been much greater.
Measles paralyzes the immune system, making it easier for other pathogens to enter the body. A 2015 study estimated that measles may be responsible for as many as half of all deaths from infectious diseases in children.
About a month after the acute illness, measles can numb the body’s initial response to other bacteria and viruses, says Dr. Michael Mina, chief scientist at digital health company eMed and a former epidemiologist at the Harvard TH Chan School of Public Health. .
That makes patients “extremely susceptible to bacterial pneumonia and other things,” says Dr. Mina, lead author of the 2015 study.
“It is very risky for people in the first few weeks after measles,” he added.
The virus also causes a kind of amnesia of the immune system. Normally the body ‘remembers’ the bacteria and viruses it has previously fought. Dr. Mina and his colleagues 2019 showed that people who have measles lose between 11 and 73 percent of their hard-won immune repertoire, a loss that can last for years.
This does not mean that the body no longer recognizes those pathogens at all, but it does mean that the arsenal of weapons available to combat them becomes smaller.
“People need to be aware that if they choose not to vaccinate, that is the position they are putting themselves and their family in,” said Dr. Mina.
The CDC recommends getting the first dose of the measles vaccine after the age of twelve months, and a second dose between the ages of 4 and 6 years. Even a single dose of the vaccine is 93 percent effective. Measles vaccination 56 million deaths prevented according to the World Health Organization between 2000 and 2021.
Vaccination rates in the United States have a clear, albeit small, dive from 95 percent in 2019-2020 to 93 percent in the 2022-2023 school year – the level needed to protect everyone in the community. Vaccination exemption rates increased in 40 states and the District of Columbia.
In a research from last yearJust over half of Republicans said public schools should require measles vaccinations, compared to about 80 percent before the pandemic. (Support for vaccines among Democrats remained steady.)
Although vaccination rates may be high at the national or state level, there may be areas with low immunization that provide tinder for the measles virus, said Dr. Omer.
If there are enough unvaccinated cases to sustain an outbreak, even those who have been vaccinated but whose immunity may have waned are vulnerable, he said.
In Idaho, 12 percent of kindergarten children do not have a vaccination record. Part of the gap stems from parents being unable or unwilling to share the data with schools, and not because their children have not been vaccinated, Dr. Hahn said.
Still, online schools, which have proliferated during the pandemic and remain popular in the state, have some of the highest rates of vaccine exemptions, she said.
In September, a young Idaho man brought back measles from international travel and became ill enough to be hospitalized. Along the way, he exposed fellow passengers on two flights, dozens of health care workers and patients, and nine unvaccinated family members. All nine developed measles.
Idaho was “very lucky” with the outbreak because the family lived in a remote area, Dr. Hahn said. But there are most likely many other areas in the state where an outbreak would be difficult to contain.
“We have plenty of tinder, if you like,” she added.
Some major outbreaks in recent years have exploded among huge groups of unvaccinated people, including the Amish in Ohio and the Orthodox Jewish community in New York City.
In September 2018, an unvaccinated child returned to New York City from Israel with the measles virus picked up during an outbreak in that country.
Although the city maintains high vaccination rates, that one case sparked an outbreak that lasted nearly 10 months, the largest in the country in decades. The city has declared a public health emergency for the first time in more than 100 years.
“We had more than 100 transmission chains,” said Dr. Oxiris Barbot, then the city’s health commissioner, and now the president and chief executive of United Hospital Fund.
“It was a challenge to keep it all straight,” she remembers. “And to have to investigate more than 20,000 of these types of exposures, that was huge.”
Working with community leaders, city officials hastily administered approximately 200,000 vaccine doses. More than 550 city employees were involved in the response, and the final cost to the city’s health department was more than $8 million.
The CDC is working with state and local health departments to identify areas with low vaccination rates and prepare them for outbreaks, said Dr. Patel. The agency also trains healthcare providers to recognize the symptoms of measles, especially in patients with a history of international travel.
Measles is a slippery opponent, but public health is well aware of the tools needed to contain the disease: screening, contact tracing and vaccinating those susceptible.
“We are not helpless bystanders,” said Dr. Omer. “The focus should be on the public health of meat and potatoes.”