Measles cases among adolescents in southern Pakistan 2012-2015: The case for revisiting vaccination strategies

Aims: Surveillance of adult measles in Pakistan is a challenge as it does not enjoy the status of a reportable disease unlike childhood cases and therefore cases remain undetected and unreported or misdiagnosed. Consequently no data or estimates of young adult cases, seroprevalence, or estimates of susceptible preadolescent or young adult population exist. We have presented both laboratory conformed and clinically suspected cases of measles occurring in adolescents and adults in the southern province of Sindh in Pakistan. Methods: Through an examination of 2 independent databases, i.e. a laboratory database of measles IgM positive cases and clinically detected cases on surveillance performed by the Disease Early Warning System, we have analyzed and reported age-specific positivity rates from 2012 to 2015 in Sindh, Pakistan. Results: High rates of laboratory confirmed measles were observed in those aged 9 y and younger. Among adolescents and adults, significantly higher positivity rates were observed among those aged 10-19y. Clinically detected cases from Sindh showed similar distribution of cases. Conclusions: High burden of cases among children <9 y of age confirm that supplementary immunization activities (SIAs) among this age group are inadequate and need to be strengthened. Cases among those 10-19y further demonstrate the need for consolidating SIAs with an additional strategy to vaccinate those who remain non-immune at college entry and in institutions where outbreaks can be prevented. Such measures are essential to achieving the goal of measles elimination in the country and region.