Last week, the Centers for Disease Control and Prevention released new information on its website reviving a widely-debunked claim that vaccines could be linked to autism. U.S. Department of Health and Human Services Secretary Robert Kennedy subsequently took responsibility for the website change change.
From a public health standpoint, the danger of misinformation around vaccination comes from the possibility that vaccination rates will fall. Vaccination is one of the best tools the public has to prevent the incidence of life-threatening diseases and reduced rates of vaccination can lead to diseases being reintroduced into local populations.
Despite the Centers for Disease Control and Prevention’s new website information, the site still hosts an useful tool for answering questions around vaccination and one major disease–measles. The Centers’ Measles Outbreak Simulator lets anyone simulate a measles outbreak in a community and what different vaccination rate and policy interventions would do to stymie the spread of the disease in the public.
Let’s look at a community of 100,000 people to see what the simulator tells us.
First, let’s look at the best-case scenario. Currently, West Virginia’s measles vaccination rate is over 98%, the highest in the United States. If a community of 100,000 with 98% vaccination rate has a measles case, the simulator expects only one measles case will occur and no one will be hospitalized. Widespread vaccination works. If we drop this number to a 95% vaccination rate, the goal rate for vaccination and the rate we see in Tennessee, we only get one additional case and a single hospitalization.
Most states are below this rate, though. The median U.S. state, South Carolina, is at 92% measles vaccination. The introduction of a single measles case in a 92% vaccinated community, though, would only lead to a total of five measles cases in our simulation community, and only a single hospitalization.
Things start to pick up once you drop below this median number, however. The 25th percentile of states (states like Arizona and Hawaii) are vaccinated at under 90%. A single measles case introduced in a community of 100,000 with 90% vaccination coverage would blossom into a total of 5,800 cases and about 860 hospitalizations. If the death rate mirrors 2025 U.S. death rates, an outbreak like that would lead to about 10 deaths.
Things get even more dangerous once you drop below 80%, which only the state of Idaho has done so far. A community of 100,000 with 80% vaccination rates would see over one in five people infected with measles, about 21,000 cases and 3,100 hospitalizations. At current U.S. measles death rates, this would also lead to about three dozen deaths.
Okay, so let’s say we get to this disaster scenario and a community at 80% vaccination rate has a measles case introduced. What can they do? Well, the simulator from the Centers for Disease Control and Prevention also lets us test different interventions.
One intervention is to catch up with vaccinations. If the community starts a vaccination campaign a few days after the first case is caught and gets 75% of unvaccinated people vaccinated over the course of a few weeks, total measles spread will drop to 16, a 99% reduction and three dozen lives saved. Even vaccinating half the unvaccinated population would lead to a 57% reduction in measles cases and save 21 lives. A more conservative campaign that only gets 20% of the unvaccinated population vaccinated would cut infection rates by 21% and save seven lives.
Less aggressive vaccination campaigns that vaccinate people more slowly or begin later are also effective at reducing measles spread. Even a five-month vaccination campaign started at the beginning of infections and reaching a total of 20% unvaccinated population vaccination rate would have similar results to stymie the spread. Similarly, a vaccination campaign that begins a few months after the first measles case is similarly effective to one that starts a few days after the first measles case. This means that the public health response should not feel like they “missed the boat” if they did not respond right away: widespread vaccination can still make a difference as long as it is implemented within a few months of the first recorded cases.
What if a community isn’t willing to turn to widespread vaccination? Another option is isolation of measles cases. The problem with this intervention is how quickly measles spreads. If 50% of people who contract measles isolate for a whole year each, only 9% of measles cases would be prevented. These durations of isolation are likely unachievable, making this an unviable strategy for making strong gains against measles.
Another option is quarantine. A communitywide quarantine would have to last more than a month and achieve 50% adherence to significantly reduce measles rates. A community of 100,000 would have to work very hard to achieve these adherence rates for this duration to stop the spread of measles in their community.
What I learned from this simulator is this: vaccination is still king when it comes to measles. As much as a barrier vaccine hesitancy is, isolating people who contract the disease from the public for a year or shutting down a community for over a month are each less practical and more disruptive than community-wide vaccination campaigns.
Which brings us back to the public policy issue at hand. The Centers for Disease Control shares in their own simulations that vaccination is the best way to prevent spread of dangerous communicable diseases. Scaled up to a state like Ohio, vaccination rates dropping from its current 89% to 80% could mean thousands of measles deaths per year. State health departments have a strong interest in combatting sources of misinformation that lead to vaccine hesitancy among the general public. If people skip out on vaccination, it puts them in harm’s way, and it also endangers their neighbors. Preventing states from backsliding on vaccinations means saving lives, preserving individual choice, and keeping the economy on its rails at the same time.