Monitoring the age-specificity of measles transmissions during 2009-2016 in Southern China

Abstract

BackgroundDespite several immunization efforts, China saw a resurgence of measles in 2012. Monitoring of transmissions of individuals from different age groups could offer information that would be valuable for planning adequate disease control strategies. We compared the age-specific effective reproductive numbers (R) of measles during 2009–2016 in Guangdong, China.MethodsWe estimated the age-specific R values for 7 age groups: 0–8 months, 9–18 months, 19 months to 6 years, 7–15 years, 16–25 years, 26–45 years, and ≥46 years adapting the contact matrix of China. The daily numbers of laboratory and clinically confirmed cases reported to the Center for Disease Control and Prevention of Guangdong were used.ResultsThe peak R values of the entire population were above unity from 2012 to 2016, indicating the persistence of measles in the population. In general, children aged 0–6 years and adults aged 26–45 years had larger values of R when comparing with other age groups after 2012. While the peaks of R values for children aged 0–6 years dropped steadily after 2013, the peaks of R values for adults aged 26–45 years kept at a high range every year.ConclusionsAlthough the provincial supplementary immunization activities (SIAs) conducted in 2009 and 2010 were able to reduce the transmissions from 2009 to 2011, larger values of R for children aged 0–6 years were observed after 2012, indicating that the benefits of the SIAs were short-lived. In addition, the transmissions from adults aged between 26 and 45 years increased over time. Disease control strategies should target children and adult groups that carry high potential for measles transmission.

Early Waning of Maternal Measles Antibodies in Infants in Zhejiang Province, China: A Comparison of Two Cross-Sectional Serosurveys

“…One of the changes was that children aged <8 months, who were expected to be protected by maternal antibodies before receiving the first dose of MV (MV1), became the age group with the greatest risk of infection in recent years. The age-specific incidence of measles among young infants was higher compared to the other age groups [7,8]. Some local serological studies conducted among young infants found that early waning of maternal antibodies against measles might be the primary cause [9,10,11,12].…”

Phylogenetic and Epidemiological Analysis of Measles Viruses in Shenzhen, China from January 2015 to July 2019

“…In Mongolia from 2015 to 2016, the measles season among children age 0–11 months occurred from July to October [16]. From 2012 to 2016, the number of confirmed measles patients under age 18 months was highest between May and August in Guangdong province [17]. In our study, 71.32% of patients were under age 18 months, which could be a factor affecting the measles season.…”

Epidemiological changes in measles infections in southern China between 2009 and 2016: a retrospective database analysis

“…Relatively high proportions of adult patients were also observed after the SIAs were introduced in other studies [20,21]. The decreasing incidence in the overall population, declining birth rate, and increasing vaccination coverage among infants and children compared to the low coverage rate in the 1980s and earlier [37,38] all contributed to the increasing mean age of infection and build-up of susceptible individuals among adults [39]. In China, infections among adults were mainly due to susceptibility caused by missed vaccinations and decreased opportunities for acquiring immunity through natural infection [38,40].…”