The rates of measles over the last few decades have fluctuated, with outbreaks and resurgences occurring here and there. Still, overall, measles is no longer the overwhelming public health concern it used to be. However, it still warrants vigilance with early detection of outbreaks and knowledgeable promotion of vaccination, so healthcare workers must remain informed on current evidence and best practices. In the following discussion, an outbreak refers to a chain of transmission with three or more confirmed cases.
After the development and widespread availability of the vaccine, there was a sharp drop in the annual number of cases, as well as complications and long-term disabilities resulting from measles, almost immediately. In 1978, a goal was set by the CDC to eliminate measles from the United States by 1982; the goal was not met. However, measles cases were down by 80%, which was still an overwhelming success (CDC, 2020b).
Starting in the late 1980s, there were a few years of notable outbreaks among vaccinated school-aged children, which brought about the current recommendation for a second dose of the measles, mumps, and rubella (MMR) vaccine between ages four and six years. After this updated recommendation and vaccine development improvements, annual measles rates continued to decline (CDC, 2020b).
In the year 2000, the United States declared measles eliminated. Disease elimination means no endemic virus transmission occurred throughout a region (in this case, the entire country) over 12 months. Sustaining elimination status is very difficult for highly contagious diseases like measles because high vaccination rates (around 95%) must be maintained, especially among children. Vaccination rates experience periodic fluctuation for various reasons, one being that the MMR vaccine is particularly controversial among the anti-vaccine community. Another reason vaccine rates have wavered in recent years is due to disruptions in typical preventative care during the COVID-19 pandemic. Both of these issues and their effects on measles vaccination rates will be discussed later on (The College of Physicians of Philadelphia, n.d.).
In 2004, measles reached an all-time low in the United States, with only 34 cases reported to the CDC for the entire year. However, as the new century progressed, several outbreaks occurred, most often linked to international travel and spreading in areas with low vaccination rates (The College of Physicians of Philadelphia, n.d.).
In 2008, there were 131 cases reported from 15 different states; this was the highest number of cases reported since 1996. In 2014, there were 644 cases reported. The outbreak continued into early 2015 when 125 measles cases were traced back to the Disney theme park in California. A review of the cases since the turn of the century indicates that about 90% of reported cases were unvaccinated individuals (The College of Physicians of Philadelphia, n.d.).
Globally, the WHO reports a 75% reduction in measles deaths at the turn of the century. However, up to 200,000 people worldwide still die from the disease annually (The College of Physicians of Philadelphia, n.d.).
The overview of measles in recent years highlights both the vaccine's overwhelming success and the very fragile control we currently have over the disease, with even the slightest disruption in adequate vaccination rates allowing the rapid spread of the illness once more.