Measles, mumps, rubella, and varicella seroprevalence in refugees in Germany in 2015

The current extent of migration poses emerging socio-economic and humanitarian challenges. Little is known on vaccination rates in migrants entering Europe, and the implementation of guidelines for serological testing and vaccination of refugees are pending.

We conducted seroprevalence analyses for measles, mumps, rubella and varicella (MMRV) in 678 refugees coming to Germany during the current crisis.

The mean age of refugees was 28.8±11.4 years, and 76.1 % of subjects were male. Overall, IgG seronegativity was 7.4 % (95 % CI 5.5-9.6) for measles, 10.2 % (95 % CI 8.0-12.5) for mumps, 2.2 % (95 % CI 1.2-3.4) for rubella, and 3.3 % (95 % CI 1.9-4.9) for varicella. Seropositivity rates were age-dependent with considerably low values in children. For example, overall MMR immunity was 90.9 % (95 % CI 88.8-93.1), but only 73.1 % of minor aged refugees displayed complete seroprevalence against all three diseases, and only 68.9 % of children and adolescents were completely MMRV immune.

Our initial data set suggests overall satisfactory MMRV immunity in adult migrants coming to Europe, but the observed low MMRV seroprevalences in refugee children support thorough and prompt vaccination of young migrants entering Europe. Taken together, our data set underlines the urgent need to implement and validate vaccination guidelines for refugee care in the current crisis.