A sero-survey to identify the window of vulnerability to measles in infants in north-eastern Nigeria

Abstract

As infants lose maternal measles antibodies (MMAs), they experience periods when their antibody levels are insufficient to protect them against measles. A prospective study was carried out at the University of Maiduguri Teaching Hospital. Sera collected from neonates at birth, and at six weeks, three months, six months and nine months of age, were analysed for MMAs by enzyme-linked immunosorbent assay. Seventy-seven neonates were enrolled. Of these, 73 (94.8%) had protective MMAs at birth. This figure declined to 36 (46.8%), 28 (36.4%), 13 (16.9%) and 4 (5.2%) at six weeks, three months, six months and nine months of age ( chi 2 =154.264, p-value=0.000). Protective MMAs at birth waned rapidly, resulting in an early window of vulnerability to measles by the age of six months. Protecting infants with early measles immunisation with potent, safe vaccines are recommended.