Measles Resurgence in Europe: Migrants and Travellers are not the Main Drivers

Measles is a highly transmissible viral infection that may lead to serious illness, lifelong complications, and death. As there is no animal reservoir for measles, measles resurgence is due to human movement of viremic persons. Therefore, some have blamed the enormous migration into Europe in the past 5 years for the measles resurgence in this region. We set out to determine the main driver for measles resurgence in Europe by assessing vaccine coverage rates and economic status in European countries, number of migrants, and travel volumes. Data on measles vaccine coverage rates with two vaccine doses of measles, mumps and rubella (MMR) [Measles Containing Vaccine (MCV)2] and total number of measles cases in 2017 for Europe, including Eastern European countries, were obtained, in addition to Gross Domestic Product (GDP), and number of migrants and tourist arrivals. The outcome measured, incidence of measles per 100,000, was log transformed and subsequently analyzed using multiple linear regression, along with predictor variables: number of international migrants, GDP per capita, tourist arrivals, and vaccine coverage. The final model was interpreted by exponentiating the regression coefficients. Incidence of measles was highest in Romania (46.1/100,000), followed by Ukraine (10.8/100,000) and Greece (8.7/100,000). MCV2 coverage in these countries is less than 84%, with lowest coverage rate (75%) reported in Romania. Only vaccine coverage appears to be the significant predictor in the model (p < 0.001) for incidence of measles even after adjusting for international migrants, international tourist arrivals, and GDP per capita. With one unit increase in vaccination coverage, the incidence of measles decreased by 18% [95% confidence interval (CI): 10-25]. Our results showed that number of migrants and international tourist arrivals into any of the European countries were not the drivers for increased measles cases. Countries with high vaccine coverage rates regardless of economic status did not experience a resurgence of measles, even if the number of migrants or incoming travellers was high. The statistically significant sole driver was vaccine coverage rates. These analyses reemphasize the importance of strategies to improve national measles vaccination to achieve coverage greater than 95%.