Abstract
This study investigated measles infection in vaccinated and unvaccinated children presenting with fever and maculopapular rash during measles outbreaks in the southern and western states of Nigeria. Measles, an acute viral illness caused by a virus in the family Paramyxoviridae, is a vaccine-preventable disease. Measles outbreak is common in Nigeria, despite the national immunization program. Children presenting with symptoms of measles infection in general hospitals and health centers in the states of southern and western Nigeria were recruited for this study. Vaccination history, clinical details, and 5 mL of blood were obtained from the children. Their sera samples were screened for specific immunoglobulin M antibodies to measles virus. Of 234 children tested (124 [53.2%] female), 133 (56.8%) had previously been vaccinated against measles virus, while 93 (39.7%) had not been vaccinated. Vaccination information for eight children could not be retrieved. One hundred and forty-three (62.4%) had measles IgM antibodies. Of these, 79 (55.3%) had been vaccinated for measles, while 65 (44.7%) had not. Despite the ongoing vaccination program in Nigeria, a high number of children are still being infected with measles, despite their vaccination status. Therefore, there is need to identify the reason for the low level of vaccine protection.