The MMR vaccine is one of the most effective vaccines ever made. Two doses are at least 99% effective at preventing measles infections. Even one dose is about 95% effective against measles.
We have measles outbreaks in the United States not because the MMR vaccine is not effective, but rather because there are still so many unvaccinated people around. Often, these unvaccinated people travel out of the country, get sick with measles, and start the outbreaks.
About Those Measles Outbreaks in China
But if the MMR vaccine is so effective, then why, as many anti-vaccine folks claim, is China having measles outbreaks when 99% are vaccinated?
The simple answer is that this claim is false – China is not having these big measles outbreaks among highly vaccinated people.
The source of the claim is from a real article in PLoS One, “Difficulties in Eliminating Measles and Controlling Rubella and Mumps: A Cross-Sectional Study of a First Measles and Rubella Vaccination and a Second Measles, Mumps, and Rubella Vaccination,” which found that in 2011, in Zhejiang province, there were:
- 9 patients with measles, including 3 infants who were too young to be vaccinated and 6 young adults who were unsure if they had ever been vaccinated
- 1122 patients with mumps
- 186 patients with rubella
So no big measles outbreaks, but why the large number of cases of mumps and rubella?
History of Measles Vaccination in China
It becomes easy to understand when you look at their immunization schedule.
In the United States, the first live measles vaccine was introduced in 1963, the MMR was introduced in 1971, and a booster dose of MMR was added to the childhood immunization schedule in 1990. That helped to stop the endemic spread of measles in 2000 and rubella in 2004.
In contrast, the measles vaccine timeline has moved much slower in China:
- a measles vaccine was introduced in 1966
- continued use of a one-dose, single-antigen measles vaccine through the 1970s and mid-1980s
- the addition of a single-antigen measles vaccine booster dose in 1985 to children who were 7-years-old
- in 2007, the switch to a measles-rubella vaccine for 8 months old, with a MMR booster at 18-24 months
- the addition of a measles-rubella vaccine booster for secondary school students in 2008
- a campaign to get children between the ages of 8 months and 4 years vaccinated with a measles-mumps vaccine in 2010
So many of the children and young adults who had mumps and rubella would not have had a chance to get a mumps or rubella vaccine. They were too old when they started giving those vaccines and there was no catch-up for older children and adults.
The study authors conclude that a timely two-dose MMR vaccination schedule is recommended, with the first dose at 8 months and the second dose at 18–24 months. An MR vaccination speed-up campaign may be necessary for elder adolescents and young adults, particularly young females.
What To Know About Those Measles Outbreaks in China
Even considering the varied vaccine schedule, the study also clearly states that even for the measles vaccine, there is less than 95% coverage in almost all age groups and that measles cases are at an historic low.
It should be clear that anti-vaccine websites are putting out false information when they say that China is having measles outbreaks when 99% of the population is vaccinated.