JONATHAN M. METSCH, Dr.P.H. – – Tracking Emerging Public Health Challenges – June 28, 2026 -Measles
So say an increasingly large number of scientists, including a public health expert who this week published an essay for one of the best known infectious disease agencies in the country.
“Call it what it is,” Jess Steier stated in the headline of her piece for CIDRAP, the Center for Infectious Disease Research and Policy. “The U.S. has lost its hold on measles elimination.”
Elimination is a formal infectious disease designation, and it’s awarded to a country when it has so thoroughly stopped spread of an illness like measles that it no longer is endemic — it doesn’t live in that country, and cases can only be imported. The United States eliminated measles in 2000, after decades of public health efforts that relied heavily on immunization.”
“There are three clues that scientists study to determine if a disease has been eliminated. First is the size and continuity of the outbreaks — at the moment, the United States is looking at what appears to be a massive, unbroken chain of spread across the country, many scientists say.
First is the size and continuity of the outbreaks — at the moment, the United States is looking at what appears to be a massive, unbroken chain of spread across the country, many scientists say.
Second is where the cases are coming from. Typically, about 40% of measles cases in the United States are imported. That means the person became infected in another country, then came to the U.S., where they may have seeded a small outbreak. Those numbers have changed dramatically: Only about 6% of measles cases are imported now, meaning the vast majority are homegrown.
And finally, scientists point to the virus’ genetic makeup as evidence that measles is spreading freely. The strain in that first Texas outbreak is almost identical to the strain circulating in an outbreak in Utah last month, “far too close to write off as a coincidence,” Steier said in her essay.
“What this pattern describes is a single family tree rather than a string of unrelated introductions from international travel,” she said.” (1)
“As a regional measles outbreak that includes more than 40 Lancaster County cases continues to grow, a handful of “very sick” adults with the virus have needed inpatient treatment at Penn State Health Lancaster Medical Center.
In these patients, measles has led to electrolyte abnormalities, kidney and liver disfunction and blood-count abnormalities, putting them at risk of organ failure, secondary infection and bleeding.
“They’re very sick, and I think that the older patients or adults may have more severe cases (than children) sometimes,”… “Adults, as we know, a lot of times … continue to go to work even if we’re sick, so there’s that risk of exposure. Whereas, children, if they’re sick, they’re usually out of school — they’re not out shopping in the grocery store.””
““If an unvaccinated person is in a room with someone who has measles, there is a 90% chance that they too will get the measles,””… (2)
“The mathematics of measles in a crowd are stark. The disease has an R0 — the number of new people one infected person will infect — of 12 to 18. For comparison, COVID-19’s R0 is roughly 2 to 3. One unvaccinated person in a packed stadium can expose dozens within minutes. The virus stays infectious in the air for up to two hours after the infected person leaves the room.
Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health, said, “I would not be surprised if we saw a measles outbreak linked to the World Cup. Crowds are an ideal place for measles virus to spread.”
The World Cup is not a one-day event. It runs 39 days — through July 19. Fans will travel repeatedly between host cities, carrying any infections they acquire across borders and into their home communities.”
“Garrow made similar remarks to CNBC: “We’re seeing outbreaks throughout the U.S. and overseas, and when you have a disease that’s as infectious as this, people just have to be in the same plane for an hour or two and all of a sudden you have an outbreak that’s transferred to somewhere else.””
“The 11 U.S. host cities — New York, Los Angeles, San Francisco, Dallas, Houston, Atlanta, Philadelphia, Seattle, Boston, Kansas City, and Miami — will each host multiple matches over several weeks. Every one of these cities is a major international airport hub, meaning any measles case generated at or around World Cup events can rapidly disperse to other cities and countries.”
The Philadelphia Inquirer reported that health officials found the Philadelphia region is “pockmarked with vulnerable communities, where vaccination rates have fallen below the rate scientists say is necessary to prevent widespread illness.” Jessica Caum, director of disease control for Philadelphia’s Department of Public Health, noted: “We’re in a different place now with measles. More cases, increases in vaccine hesitancy, decreases in vaccination rates — all of these things are important to keep in mind.” (3)
World’s most contagious disease found at busy California airport, https://nypost.com/2026/06/25/health/worlds-most-contagious-disease-found-at-busy-california-airport/
Officials warn of measles exposure at Terminal 5 at O’Hare International Airport, https://www.cbsnews.com/chicago/news/measles-exposure-terminal-5-ohare-international-airport/
Measles case confirmed in Maryland resident who passed through Dulles and DC clinic, https://wtop.com/health-fitness/2026/06/measles-case-confirmed-in-maryland-resident-who-passed-through-dulles-and-dc-clinic/
1.U.S. may have lost a ‘crown jewel’ of public health, experts say, By Erin Allday, https://www.sfchronicle.com/health/article/measles-vaccine-united-states-us-22319350.php
2.Doctors warn of severe adult measles cases as Lancaster County outbreak grows, by ANNE GARBER, https://lancasteronline.com/news/health/doctors-warn-of-severe-adult-measles-cases-as-lancaster-county-outbreak-grows/article_bcb72e69-13bd-4016-a9c1-5831f627a8a0.htm
3.Public Health Officials Say Measles Poses a Bigger World Cup Threat Than Ebola, By Dorothy Brooks, https://www.medicaldaily.com/measles-world-cup-2026-health-risk-philadelphia-public-health-warning-475807
curated by Jonathan M. Metsch, Dr.P.H.
Clinical Professor of Environmental Medicine, Icahn School of Medicine at Mount Sinai