Childhood vaccination rates against measles fell in the years after the COVID-19 pandemic in nearly 80% of the more than 2,000 U.S. counties with available data — including in states that are battling outbreaks this year.
A Johns Hopkins University study, published in JAMA this week, illustrates where more vulnerable communities are located. The results mirror trends established at state and national levels: Routine childhood vaccination rates are dropping.
“When you look at the state level or national level … you really don’t see those drastic drops. Those are there. They’re real and they’re really problematic,” said Lauren Gardner, an expert in infectious disease modeling at Johns Hopkins University who is the paper’s senior author. Gardner also built the university’s COVID-19 database.
Most of the measles cases in the U.S. this year — 1,088 nationally as of Friday — are in unvaccinated people. It has been spreading among communities due to international and domestic travel. Three people have died from measles during this year’s outbreaks, and 2025 is inching closer to becoming the worst for measles in more than three decades.
Measles was eliminated in the U.S. in 2000, and the vaccine is safe and highly effective. Public schools nationwide require two doses of the measles, mumps and rubella vaccine before kindergarten, but the number of children with non-medical exemptions from those requirements hit an all-time high in the 2023-2024 school year. Health experts say community-level vaccination needs to be at 95% or higher to prevent outbreaks.
The Johns Hopkins study looked at 2,066 counties across 33 states, comparing kindergarten vaccination rates averaged over school years from 2017-2020 to averages from 2022-2024. Where kindergarten data wasn’t available, the researchers used a comparable rate.
Here’s what it looks like in counties where there have been outbreaks this year, including in Texas counties that are the epicenter of measles.
Texas
Texas has logged 742 measles cases since late January, most in West Texas.
Gaines County has 411 cases, the most in the state. Almost 2% of its population got measles. While the county saw a two percentage-point increase in vaccination rates after the pandemic, its 82.4% rate remains below herd immunity.
Terry County (60 cases) and Yoakum County (20 cases) dropped below the 95% threshold for herd immunity after the pandemic, to 93.7% and 91.8% respectively.
Lubbock County — which has seen 53 cases and is the closest metro area to Gaines County — was just below 95% before the pandemic, but dropped three percentage points after to 91.8%.
El Paso County on the border of Mexico has had the third-most measles cases in Texas this year with 57. Its vaccination rate is higher than 95% but saw a 2.1 percentage-point decline to 96.5%.
Kansas
Counties with outbreaks in Kansas include Gray with 25 cases, Haskell with 11 and and Stevens with seven.
Vaccination rates in Gray County dropped 23 percentage points after the pandemic, from 94% to 71%.
Haskell County dropped 18 percentage points to 65%. And Stevens County dropped 0.5 percentage points to 90.5%.
Colorado
Colorado’s outbreak, which is linked to an international flight that landed at the Denver airport in mid-May, involves six cases: five in state residents and one out-of-state traveler.
Two people who got measles live in Arapahoe County in the Denver metro, where the vaccination rate dropped 3.5 percentage points to 88.4%. Three others live in El Paso County, home to Colorado Springs, where the vaccination rate dropped 3.8 percentage points to 80% post-pandemic.
North Dakota
Pre-pandemic data in North Dakota wasn’t available to Johns Hopkins researchers, but they looked at rates from school years ending in 2022, 2023 and 2024.
North Dakota’s first outbreak started in Williams County, which now has 16 measles cases. In the timeframe researchers looked at, vaccination rates in Williams rose from 84.6% in 2022 to 87.7% in 2023, only to drop back to 83.5% in 2024.
Cass County has seven cases, and its rate has stayed steady at about 92.7%, while Grand Forks County, which has 10 measles cases, dropped from 95.4% to 93.4%.
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