Measles transmission among adults with spread to children during an outbreak: Implications for measles elimination in China 2014.

Monday, 18th of July 2016

Vaccine. 2016 Jun 18. pii: S0264-410X(16)00232-2. doi: 10.1016/j.vaccine.2016.02.051. [Epub ahead of print]

Measles transmission among adults with spread to children during an outbreak: Implications for measles elimination in China 2014.

Ma C¹ Yan S¹ Su Q¹ Hao L¹ Tang S¹ An Z¹ He Y¹ Fan G¹ Rodewald L¹ Wang H².

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Abstract

INTRODUCTION:

Following implementation of Chinas 2006-2012 Action Plan for measles elimination which led to a nadir of measles in 2012 a resurgence started in 2013 that continued into 2014. Measles typically is a disease that mainly affects children. We investigated a community outbreak in 2014 with measles virus transmission among adults without children serving as virus reservoirs. Our investigation highlights adult susceptibility to measles.

METHODS:

We conducted a retrospective active case search and analyzed confirmed case data to describe person place and time characteristics of the outbreak. All individuals with measles with onset during the first 2 months of the outbreak were interviewed face-to-face to determine source(s) of infection and transmission route (from whom and to whom).

RESULTS:

Among the 280 cases 220 (77.6%) were among ≥20-year-old adults 24 (8.6%) were among 8-23 month olds 22 (7.9%) were among <8-month-old infants and the remaining 14 (5.9%) were among 2-19 year olds. Of the 83 cases in the early stage of the outbreak 41 (49.4%) were acquired in the community 24 (28.9%) were acquired nosocomially 13 (15.7%) were acquired by family contact and 5 were imported. Among 44 clearly determined transmission linkages 37 (84.1%) were adult to other age-group (these include 29 adult-to-adult seven adult-to-child and one adult-to-infant) six were from infants to adult and children and one was child-to-child. Outbreak response immunization activities were implemented by non-selective supplementary immunization activities with 51.3% of targeted 5-19-year-old children and adolescents and 30.2% of targeted 20-49-year-old adults being vaccinated.

CONCLUSIONS:

Despite high population immunity among children and adolescents following three rounds of measles vaccine supplementary immunization activities sustained measles virus transmission still occurred among adults in this community. Adult measles immunity gaps might threaten measles elimination highlighting the importance targeting susceptible adults during outbreak response immunization.

Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.