Emergency settings: be prepared to vaccinate persons aged 15 and over against measles.

In their landmark article on measles prevention in emergency settings, Toole and colleagues recommended in 1989 that all children aged 6 months to 5 years should be immunized with measles vaccine at the time they enter an organized camp or settlement [1]. In 2000, Salama and colleagues documented substantial mortality during a famine emergency in Ethiopia, with measles and malnutrition as major contributing factors. In a retrospective study of mortality, measles alone, or in combination with wasting, accounted for 35 (22.0%) of 159 deaths among children younger than 5 years and for 12 (16.7%) of 72 deaths among children aged 5–14 years. The setting was a rural population without routine childhood immunization and exposure to natural measles virus infection [2]. The authors concluded that measles vaccination, in combination with vitamin A distribution, should be implemented in all types of complex emergencies. Vaccination coverage should be 90% and extended to children up to age 12–15 years [2]. A vaccination age range up to 14 years was included in the World Health Organization (WHO)/United Nations Children’s Fund (UNICEF) statement to reduce measles mortality in emergencies [3], and the revised SPHERE project guidelines [4]. However, since then, the discussion about target age groups has increasingly included the potential need to vaccinate adults. As early as 2000–2001, Kamugisha and colleagues documented 21% of measles cases that were 16 years and older in a major outbreak in Tanzanian camps with refugees from Burundi [5]. The authors concluded that in some emergency settings, achieving population immunity adequate to prevent virus transmission may require vaccinating persons older than 15 years, and the selection of target age groups for vaccination should consider measles epidemiology in source and refugee populations [5]. A recent review documented additional measles outbreaks in emergencies that included adult cases [6], and the recommendation to review the measles epidemiology to inform decisions about vaccination target age groups has increasingly become standard in emergency [7, 8] and nonemergency settings [9]. This shift in recommendations has been a result of the changing epidemiology of measles in Africa [10]. In this issue of The Journal of Infectious Diseases, Navarro-Colorado and colleagues remind us of the need to consider those changes in epidemiology when responding to measles outbreaks in displaced populations, and to be prepared to vaccinate adolescents and adults. In 2011, a massive influx of refugees occurred to camps in Dadaab, Kenya, and Dollo-Ado, Ethiopia, when Somalis fled severe drought and ongoing armed conflict in their countries. Given that these refugees, after walking for weeks without food or services, generally arrived in poor health and often malnourished, and reports that implementing comprehensive measles control and elimination strategies in Somalia remain challenging [11], the authorities implemented vaccination on arrival to camps and routine immunization in clinics for children aged 6–59 months (Ethiopia) and 9–59 months (Kenya). In Dadaab, Kenya, a nonselective measles vaccination campaign was conducted for children aged 9 months to 14 years from 28 March to 7 April 2011. Measles outbreaks started 6 June 2011 in camps in Kenya and 9 July 2011 in camps in Ethiopia. The authors reported that the outbreak was known to affect adolescents and adults aged ≥15 years in Kenya in week 27, which corresponds to 3–9 July 2011; and in Ethiopia in week 29, which corresponds to 17–23 July 2011. However, because of lack of a policy agreement and limited availability of vaccines, no refugees aged ≥15 years were vaccinated before August 2011,whenvaccinationonarrival incamps Received and accepted 13 August 2014; electronically published 5 September 2014. Correspondence: Reinhard Kaiser, MD, MPH, Immunization, Vaccines, and Emergencies, WHO InterCountry Support Team, East and Southern Africa, 86 Enterprise Road, Harare, Zimbabwe ([email protected]). The Journal of Infectious Diseases 2014;210:1857–9 Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. Thiswork iswritten by (a) US Government employee(s) and is in the public domain in the US. DOI: 10.1093/infdis/jiu463