Although measles was declared eliminated in the United States in 2000, almost 1,300 cases of measles were reported in 31 states in the U.S. in 2019— the greatest number since 1992. The 2019 U.S. measles outbreaks were all linked to travel-related cases that reached at-risk populations (un or under vaccinated against measles) in the United States.
Increase in Measles Cases — United States, January 1–April 26, 2019, | MMWR
Outbreaks can happen in areas where people may be unvaccinated or under-vaccinated, including the United States. Right now, measles outbreaks are occurring in every region of the world. Measles can enter the United States through infected travelers entering or travelling through to the U.S. as well as through infected U.S. travelers returning from other countries.
Top 10 Countries with Global Measles Outbreaks
Rank Country Number of Cases
1 India 67,592
2 Yemen 23,680
3 Pakistan 5,853
4 Cameroon 4,926
5 Nigeria 4,389
Over 61 million doses of measles-containing vaccine were postponed or missed due to COVID-19 related delays in supplementary immunization activities. This increases the risk of bigger outbreaks around the world, including the United States.
Childhood Vaccination Rates Continue to Drop In the 2021-2022 School Year
As the years have gone by, more and more people are becoming susceptible to measles. Pretty much everyone over 63 had measles as a kid and those that recovered have lifetime immunity. Cases of measles plummeted in the US after mass vaccination campaigns in the early 1960s. The US (and Arizona) enjoyed very high vaccination rates in the next 4 or 5 decades… but after that vaccination levels started declining coinciding with the ‘anti-vax’ movement.
Vaccination rates continued to slide over the last 10 years, and the statewide immunization rate for Kindergarteners now at 91%, well below the community immunity threshold for measles of 95%. Kids that don’t get caught up (or get vaccinated once they turn 18 because their parents had not vaccinated them as kids) will remain susceptible to infections as an adult. Cases of measles tend to be worse among kids under 5 and adults over 20. Measles Clinical Information
Right now, most susceptible people in the US are under 25 years old, as childhood measles vaccination rates were very high between 1963 and 2000. Most outbreaks of measles in the US these days are a result of a susceptible young adult (unvaccinated) travels abroad to a country with lots of measles and return to communities with low vaccination rates.
Vaccination rates aren’t uniform across the state. Yuma and Santa Cruz counties continue to enjoy the highest vaccination rates (above 95% for MMR among Kindergarteners). Yavapai consistently has the lowest vaccination rates with MMR coverage at only 74% and nearly 10% of students totally unvaccinated among Kindergarteners.
The ‘Vaccines for Children’ Program Is Critical to Maintaining Childhood Vaccination Rates… but Provider Participation Plummeted During the Ducey Administration
Another continuing trend… students enrolled in charter schools have vaccination rates much lower than students in district public schools. Also, higher income districts tend to have lower vaccination rates.
There are evidence-based strategies that can be implemented at a statewide level, but such initiatives require leadership by a state health department.
Interventions to increase pediatric vaccine uptake: An overview of recent findings
For information on school immunization requirements, review the Guides to Arizona Immunization Requirements for Child Care/Preschool and Grades K-12.
