credit: Rayne Zaayman-Gallant / European Molecular Biological Lab
In the spring and summer of 2017, Minnesota experienced the largest outbreak of measles since 1990. More than 8,000 people were exposed, 500 stayed at home because they were potentially infectious, and 22 people were hospitalized. Seventy one cases were among people who had not been vaccinated. And 81% of all cases were among Somali immigrants, a group than in 2014 had a vaccination rate of only 42%. A CDC analyses concluded that rates declined due to “concerns about autism, the perceived increased rates of autism in the Somali-American community, and the misunderstanding that autism was related to MMR.”
Cases spiked in the spring but by June public health officials were able to contain it. By August, state health officials announced an end to the outbreak.
The Minnesota outbreak offers several lessons
First, high vaccination rates among the Minnesota population protected most people and checked the growth of the virus. For measles, the desired vaccine rate is 93% . Yet high statewide averages concealed much lower vaccination levels in certain regions, among specific groups. The Minnesota case demonstrates that a highly contagious but vaccine preventable virus like measles is very effective at finding the unvaccinated.
Second, amid the outbreak, vaccine skepticism deteriorated. The graph below shows that as measles cases peaked in April and May, MMR vaccine doses administered – especially in the hardest hit parts of state, increased dramatically. Compared to the previous year, thousands of more doses were administered. Since 2017, Minnesota has had only 2 confirmed cases of measles.
Anxiety about a disease seemed to overwhelm misinformation about vaccines. The outbreak threatened many of the unvaccinated – particularly those in the impacted region. Vaccines transformed from a potentially hazardous substance to a welcomed remedy. Vaccine skepticism may not be so deeply rooted after all.
Third, in 2000, the World Health Organization declared measles eliminated from the United States. But international travel reintroduced the disease and, as Minnesota demonstrated, lower vaccination rates contributed to local outbreaks.
In 2019, New York and Washington declared public health emergencies in response to significant measles outbreaks. Clark county Washington was the epicenter and considered an anti-vaxxer hot spot. Most cases were children under 10. The Washington legislature responded quickly and passed a bill that limited exemptions for the MMR vaccines and children could not attend public or private school without proof of vaccination or exemption records.
In New York, a flight attendant developed measles which then spread to several Brooklyn neighborhoods. The mayor ordered mandatory vaccinations and the unvaccinated were barred from public places for 30 days. The New York legislature later enacted a law repealing religious and philosophical exemptions to vaccinations.
In total, 1282 cases occurred in 2019 across 30 states – the largest number since WHO declared measles eliminated from the United States (see graph below). The outbreaks inspired many states to tighten vaccines exemption laws.
Finally, the Minnesota case and others illustrate what may eventually occur with COVID-19. The Minnesota governor and opposition party supported public health officials. Political elites did not send competing messages. Health officials were decisive and broke the chains of transmission. Similarly, in New York and Washington public health officials moved swiftly, beat back the virus, and the legislatures and governors responded with laws that tightened vaccination requirements and refined specific exemptions. In short, local, and state governments cooperated.
The COVID-19 future
Measles was not eliminated – even though 90% plus of the public was vaccinated. For many highly contagious diseases, full immunity may never be realized – eradication may not be possible. Rather, public health strategies will focus on containment. After all, COVID-19 vaccines — while highly effective — won’t last a lifetime. Health experts in fact often discuss a booster or annual shot for COVID-19. Thus, like the flu, COVID-19 likely becomes a constant feature of life, expanding in one season and diminishing in another.
Even if COVID-19 immunization rates surpass 85% to 90% – year after year, that does not guarantee rates would be equal across states or across counties within the states. Some counties will show modest participation while others will reach maximum levels.
This patchwork reflects federalism and the politicization of COVID-19. Future outbreaks are inevitable. The fight against COVID will continue for some time. The virus may recede, temporarily, and then resurface in various regions across the country.
When cases spike, state and local public health officials will act quickly to stop transmission. The news media will report events, the CDC will follow up, health officials will gather data, and state legislatures will scrutinize vaccination laws. Vaccination rates will increase among those impacted and cases decline.
Past measles outbreaks offer a roadmap. The knowledge and infrastructure is in place – and with the latest 2 trillion dollar COVID relief bill, it should receive a considerable influx of resources.