London's catch-up vaccination campaign against measles, mumps, and rubella reaches less than a quarter of children who were unvaccinated

Triangulation of measles vaccination data in the United Kingdom of Great Britain and Northern Ireland

Objective

To illustrate how data triangulation involving routine data sources can optimize data usage and provide insights into vaccine programme effectiveness by considering measles vaccination and disease incidence data in England.

Methods

We obtained data on measles, mumps and rubella (MMR) vaccine coverage in birth cohorts from 1985 to 2016 from child health records and adjusted for under-ascertainment and catch-up campaigns. We assumed that the population had no natural immunity and that vaccine effectiveness was 95% for one dose and 99.75% for two doses. Vaccinations done outside the routine schedule and in people who entered England after the age of immunization were identified from primary care records. Measles susceptibility was defined as the percentage of individuals who were not immune despite all vaccination activities. We triangulated measles susceptibility and incidence data.

Findings

Median susceptibility was 4.6% (range: 1.2–9.2). Among cohorts eligible for two MMR vaccine doses, those born between 1998 and 2004 were most susceptible. Measles incidence was highest in these cohorts. Data from primary care and child health records were comparable for cohorts after 2000, suggesting that little supplementary vaccination took place. For cohorts before 2000, primary care data quality was insufficient for accurately estimating coverage.

Conclusion

Triangulating routine data on measles vaccination coverage and disease surveillance provided new insights into population immunity and helped identify vulnerable groups, which was useful for prioritizing public health actions to close gaps in immunity. This approach could be applied in any country that routinely records vaccine coverage and disease incidence.

Evaluation of the measles, mumps and rubella vaccination catch-up campaign in England in 2013

In January-March 2013 in England, confirmed measles cases increased in children aged 10-16 years. In April-September 2013, the National Health System and Public Health England launched a national measles-mumps-rubella (MMR) campaign based on data from Child Health Information Systems (CHIS) estimating that approximately 8% in this age group were unvaccinated. We estimated coverage at baseline, and, of those unvaccinated (target), the proportion vaccinated up to 20/08/2013 (mid-point) to inform further public health action. We selected a sample of 6644 children aged 10-16 years using multistage sampling from those reported unvaccinated in CHIS at baseline and validated their records against GP records. We adjusted the CHIS MMR vaccine coverage estimates correcting by the proportion of vaccinated children obtained through sample validation. We validated 5179/6644 (78%) of the sample records. Coverage at baseline was estimated as 94.7% (95% confidence intervals, CI: 93.5-96.0%), lower in London (86.9%, 95%CI: 83.0-90.9%) than outside (96.1%, 95%CI 95.5-96.8%). The campaign reached 10.8% (95%CI: 7.0-14.6%) of the target population, lower in London (7.1%, 95%CI: 4.9-9.3) than in the rest of England (11.4%, 95%CI: 7.0-15.9%). Coverage increased by 0.5% up to 95.3% (95% CI: 94.1-96.4%) but an estimated 210,000 10-16 year old children remained unvaccinated nationally. Baseline MMR coverage was higher than previously reported and was estimated to have reached the 95% campaign objective at midpoint. Eleven per cent of the target population were vaccinated during the campaign, and may be underestimated, especially in London. No further national campaigns are needed but targeted local vaccination activities should be considered.

Impact of supplementary immunization activities in measles-endemic areas: a case study from Guangxi, China

Because of limited resources, each year during the period from 1999 through 2007, only about one-quarter of the 111 counties in Guangxi province were selected by means of risk assessment to participate in Supplementary Immunization Activities (SIAs), targeting children aged 8 months to 14 years during 1999-2003 and 8 months to 10 years during 2004-2007. Approximately 2 million doses of measles vaccines were administrated each year during SIAs. Estimated from the National Notifiable Diseases Surveillance System, with a reliable internal consistency over years, the average annual incidences of measles before SIAs (1993-1998), during the first phase (1999-2003), and during the second phase (2004-2007) were 16.05, 9.10, and 2.46 cases per 100,000, respectively. The overall provincewide annual incidence decreased by 84.67%, from 12.12 cases per 100,000 in 2000 to 2.10 cases per 100,000 in 2007. The percentage of counties with annual incidence ≥10 cases per 100,000 decreased from 55% in 1993 to <1% in 2007. Compared with the pre-SIA period, the greatest decrease in annual incidence was 83.93% for the 10-14.9-year-old group and the smallest decrease was 46.16% for children <1 year old. The multiple-year SIAs targeting children in selected high-risk counties were effective in controlling measles in mountainous, impoverished, and multiethnic measles-endemic areas.