Roughly two decades ago, doctors had eliminated measles within the United States. It is now back. According to the CDC, there have been 760 cases of measles in The United States since this past January.
A new study published in the journal “Science” finds the US is moving backward on the usual path of disease elimination. Researchers studied thirty years’ worth of data compiled by the World Health Organization (WHO) on vaccination rates and measles cases. They found that countries trying to eliminate measles follow a predictable path as they do so.
In the beginning, there would be lots of measles cases, but the number of cases would drop as vaccination rates increased. In countries just starting anti-measles programs, most patients would be children. As the program progressed, however, more children would be vaccinated and measles would be seen more often in older people.
As the number of measles cases drop within a country, outbreaks become sporadic and harder to predict. Some years might see several outbreaks while other years would see no outbreaks. Eventually, there would be fewer and fewer outbreaks until measles was eliminated altogether in a region or country.
The researchers found that countries could veer from the path for both good or bad reasons. In some cases, a country would have a very strong and successful elimination program that would enable them to zip through the period of unpredictable outbreaks and head straight to elimination. This seems to have been the case with some countries in the Americas. North and South America had shared the distinction of being the only continents to have fully conquered measles, until measles cases appeared in the US, Brazil and Venezuela. Brazil had over 2,000 cases in 2018, and Venezuela had over 5,000 cases during that same year.
Bad reasons include failed programs and refusal to get vaccinated. While the US is still further along the path to total elimination of measles within its borders than many other countries, it has now re-entered the period of sporadic and unpredictable outbreaks.
WHO has a goal of eradicating measles from its sex regions, which include every continent except Antarctica. None of its regions have currently met that goal.
