Pennsylvania Measles Outbreak Passes 1,500 Cases as US Tally Hits Highest Level Since 1991

Pennsylvania’s measles outbreak has passed 1,500 confirmed cases, state health officials confirmed on Monday 9 November 2026, as the disease keeps spreading across 45 of the state’s 67 counties. The milestone makes Pennsylvania by far the hardest-hit state in a year that has already produced more measles cases across the United States than any year since 1991.

The Pennsylvania Department of Health put the total at 1,505 cases as of 9 November, up 18 from its previous update on Friday 6 November. Seventy-three new cases were recorded in the previous seven days, and hospitalisations rose to 290, with six measles-associated deaths reported in the state this year.

Pennsylvania measles outbreak — the key figures

The 1,505 figure is a cumulative total for 2026, not the number of people infectious at one time. Even so, health officials say the pace of new infections shows the outbreak is far from over.

The week Pennsylvania crossed 1,500 cases

The latest state update, reported by Reuters on 9 November, showed the outbreak still adding dozens of cases a week. Eighteen cases arrived between Friday 6 November and Monday 9 November alone, and the seven-day rise of 73 cases was one of the sharpest weekly increases of the year.

Bucks County, in the south-east of the state, reported a new case on 9 November in a resident who had recently travelled to an area of central Pennsylvania with many measles cases this year. The case showed how the outbreak, long centred on one region, is now reaching counties that had previously escaped it.

Pennsylvania’s health department has recorded six measles-associated deaths in 2026, including three people from Lancaster County, two from Jefferson County and one from Mifflin County. The CDC’s national tally lists four confirmed measles deaths for 2026, a figure the agency says is subject to change as state reports are reviewed. State and federal counts can differ while investigations continue, and the CDC notes that states hold the most up-to-date information about outbreaks in their own jurisdictions.

Lancaster County remains the centre, but the map is widening

Lancaster County, in the south of the state, still accounts for roughly a third of Pennsylvania’s total, and it was the early centre of the outbreak. The growth is no longer confined there. Central and north-eastern Pennsylvania now account for 163 confirmed cases, led by 52 each in Clinton and Snyder counties, according to the state health department.

The spread is visible in the county breakdown. Union County has recorded 20 cases, Northumberland County 14, Lycoming County eight, Schuylkill County seven, Columbia County five, Montour County four and Bradford County one. Two-thirds of Pennsylvania’s counties have now reported at least one case.

The pattern matches what epidemiologists expect from measles. The virus spreads through the air and can linger in a room for up to two hours after an infected person leaves, so a single case in a community with low vaccination coverage can seed a cluster within days.

The national picture: 5,182 cases, the most since 1991

Pennsylvania’s outbreak sits inside a national resurgence. The CDC reported 5,182 confirmed measles cases across the United States as of 5 November 2026, more than double the 2,289 recorded in the whole of 2025. It is the highest annual tally since 1991, before a second routine dose of the measles vaccine became standard.

Forty-three outbreaks have been reported in the United States in 2026, and 96% of confirmed cases are linked to outbreaks. Most infections — 59% — are among children and teenagers, according to CIDRAP’s analysis of the CDC data. Nationally, 562 people have been hospitalised, about 11% of all cases.

The scale of the resurgence has put the United States’ measles elimination status under review. A Pan American Health Organization commission met from 10 to 13 November 2026 to assess whether measles has circulated continuously in the country for more than 12 months, which could cost the US the elimination status it has held since 2000.

Why the virus is finding room to spread

Measles was declared eliminated in the United States in 2000, meaning the virus was no longer spreading continuously within the country. Its return is tied directly to vaccination gaps. The CDC reports that 96% of confirmed cases in 2026 involve people who were unvaccinated or whose vaccination status is unknown. A further 2% had received one dose of the MMR vaccine, and 2% had received two doses.

Two doses of the MMR vaccine are 97% effective at preventing measles, and one dose is 93% effective, according to the CDC. The vaccine is normally given first at 12 to 15 months of age, with the second dose between the ages of four and six, before school entry.

Coverage has slipped below the level needed to stop the virus circulating. CDC data show 92.4% of kindergarten pupils received the recommended MMR vaccinations in the 2025–26 school year, below the roughly 95% coverage needed in every community to keep measles from spreading. Health officials say reported counts probably understate the true spread, because not everyone who falls ill gets tested.

Measles is not the only health story drawing official warnings this month: salmonella in Ukrainian eggs led to a UK recall, with shoppers and caterers told what to check.

What health officials want people to do

The advice from the CDC and the Pennsylvania Department of Health is straightforward: check your vaccination status, and make sure children have had both doses of the MMR vaccine. Anyone unsure of their status should contact their clinician or local health department, which can check records and arrange a catch-up dose.

People who develop a high fever, cough, runny nose and red, watery eyes followed by a rash — the classic measles symptoms — after possible exposure should telephone a clinician or clinic before visiting in person, so that other patients, especially babies and people with weakened immune systems, are not exposed in a waiting room. Measles can lead to pneumonia, brain swelling and death, and the risk is highest in young children, pregnant women and people whose immune systems are weakened.

Health agencies on both sides of the Atlantic are urging the public to heed official alerts — the UKHSA issued its first yellow cold-health alert of the winter this week.

The next state update will show whether the weekly rise is slowing. The Philadelphia Inquirer has described the outbreak, the largest in the United States in three decades, as showing signs of slowing, but dozens of new cases are still being confirmed each week.

Your questions on the Pennsylvania measles outbreak, answered

How many measles cases does Pennsylvania have?

1,505 confirmed cases as of 9 November 2026, across 45 counties, with 290 hospitalisations and six measles-associated deaths, according to the Pennsylvania Department of Health.

How many measles cases are there in the United States in 2026?

5,182 confirmed cases as of 5 November 2026, according to the CDC, the highest annual total since 1991. More than double the 2,289 cases recorded in 2025.

How effective is the MMR vaccine?

Two doses are 97% effective at preventing measles, and one dose is 93% effective, according to the CDC. The first dose is given at 12 to 15 months, the second between ages four and six.

Who is most at risk from measles?

Young children, pregnant women and people with weakened immune systems face the highest risk of serious complications, including pneumonia and brain swelling. Most US cases in 2026 — 59% — are among children and teenagers.

Could the United States lose its measles elimination status?

Possibly. A Pan American Health Organization commission met from 10 to 13 November 2026 to decide whether measles has circulated continuously in the US for more than 12 months. Losing elimination status would be a formal recognition that the virus is spreading within the country again.

Myth-busting: what is not true about the Pennsylvania measles outbreak

One common claim is that measles is a harmless childhood illness. It is not: 290 people in Pennsylvania alone have needed hospital care this year, and six have died. Another is that a single dose of the MMR vaccine is enough. It is not: one dose is 93% effective, while two doses reach 97%, which is why health officials stress completing the course. A third is that the outbreak is confined to one county. It is not: 45 of Pennsylvania’s 67 counties have now reported cases.