Measles can become epidemic – vaccination coverage is too low in places

Measles was eradicated from Finland in the 1990s thanks to good vaccination coverage, but the disease has returned during the past decade. 

A report by the National Institute for Health and Welfare (THL) shows that the vaccination coverage of the MMR vaccine, which prevents measles, is still 95 per cent on average, but the coverage is below that level in many towns and municipalities.

“Large regional differences are a major concern. Even if the vaccination coverage for a given municipality is at a good level, there may be dozens or even hundreds of unvaccinated children in a given village or school. Even one case of measles in such a group results in a high probability of a measles epidemic,” says Senior Medical Officer Taneli Puumalainen from the National Institute for Health and Welfare.

According to studies, herd immunity requires a vaccination coverage of 95 per cent. At lower levels of vaccination coverage, those who are unvaccinated are at higher risk of infection. There are 61 municipalities in Finland where the measles vaccine is administered to less than 95 per cent of children. These municipalities include several population growth centres with large numbers of children.

Measles is highly contagious and one patient infects approximately 15–17 other people. The number of people exposed to the disease may be very high. In Kainuu, for example, a total of 150 people were exposed to measles due to one patient visiting a health centre and hospital. Tracking these people down took a full working day for four public health nurses, two head nurses and 1.5 physicians. A total of 62 people were vaccinated.

Each year, there are measles epidemics in Europe with thousands of people taken ill. As Finns travel a lot, exposure to the disease can occur at any time.

Sources:

• Helsingin Sanomat (in Finnish)
• THL (in Finnish)