Measles Elimination: Identifying Susceptible Sub-Populations to Tailor Immunization Strategies

Viruses
Volume 11, Issue 8 (August 2019)
https://www.mdpi.com/1999-4915/11/8

 

Open Access Communication
Measles Elimination: Identifying Susceptible Sub-Populations to Tailor Immunization Strategies
by Peter Kreidl, David Ammerer, Reinhard Würzner, Anita Luckner Hornischer, Dorothee von Laer and Wegene Borena
Viruses 2019, 11(8), 765; https://doi.org/10.3390/v11080765
Received: 31 July 2019 / Revised: 14 August 2019 / Accepted: 16 August 2019 / Published: 20 August 2019
Abstract
Measles elimination has been identified as a public health priority in Europe for a long time but has not yet been achieved. The World Health Organization (WHO) recommends identification of susceptible sub-populations to target supplementary immunization activities. We used three different sources of information: retrospective samples investigated for measles IgG between 1997 and 2016, vaccine coverage data from the existing electronic registry for birth cohorts 2015 to 1999, and surveillance data from 2009 until 20 July 2019. We calculated susceptibility by birth cohort using seroprevalence data, adjusting vaccine coverage data with reported effectiveness (93% for the first and 97% for the second dose, respectively), and compared it with measles incidence data, aggregated by birth cohorts and districts. Susceptibility levels for persons 10–41 years (birth cohorts 2007–1976) were 10.4% and thus far above the recommended values of WHO (5%). Older birth cohorts were sufficiently protected. Districts with the highest susceptibility estimates corresponded with districts with the highest incidence rates. Birth cohorts with susceptibility levels > 10% showed a 4.7 increased relative risk of having had more than one measles case. We conclude that retrospective serosurveys are a cheap and useful approach in identifying susceptible sub-populations, especially for older birth cohorts whose coverage data remain scarce.