Effectiveness of a nationwide measles vaccination campaign in Libya, 2005: Retrospective study

Abstract

Background: Measles is a highly contagious virus. An effective vaccine has been widely administered for over three decades, but the measles burden is still high, causing 134,200 deaths globally in 2014. In Libya, a national mass measles vaccination campaign took place in 2005 targeting all residents of Libya age 9 months to 20 years between February 2005 5, and March 1, 2005. To date, no evaluation of its effectiveness has been conducted. Materials and Methods: Measles surveillance data were obtained for a 6 years' period (2002–2007) spanning the 3 years before and the 3 years following the mass vaccination campaign. The incidence of measles cases was calculated pre- and postvaccination campaigns and relative change in incidence was determined. Results: During the campaign 2,431,167 people age 9 months–20 years were vaccinated, resulting in a coverage rate of 98.4% in that age range. Comparing incidence of measles cases pre-and postvaccination campaign demonstrates an effectiveness of 96%, P = 0.021. Seasonality of measles cases was identified with a peak in April and May. Effectiveness varied by the age group, ranging from 82% in people lower than 5 years of age. Conclusion: A significant reduction was demonstrated following a national immunization campaign. Supplementary immunization campaigns should be initiated to keep the Libyan measles rate low; allowing the country to move into an elimination period.