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

An Upsurge of Measles Cases in Mali-a Consequence of Pandemic-associated Disruption in Routine Immunization

Measles deaths highlight immunization program gaps. In the Child Health and Mortality Prevention Surveillance study in Mali, we observed a rise in under-5 measles-related deaths in 2022 that corresponded with increased measles cases at the same time and a decline in measles vaccine coverage in Mali in 2020.

Two media-reported vaccine events in China from 2013 to 2016: Impact on confidence and vaccine utilization

BACKGROUND

China media reported infant deaths following hepatitis B vaccination in late 2013, leading to temporary suspension of hepatitis B vaccine (HepB Event) until the deaths were shown to be coincidental and the vaccine was of standard, good quality. In 2016, a criminal ring in Shandong province that had been purchasing, improperly storing, and reselling Category 2 vaccines (private-sector) to 60 (of 200,000) clinics for 5 years, was exposed, publicized, and prosecuted, and the potential health and epidemiological impacts were investigated to determine whether revaccination was necessary (Shandong Vaccine Event).

METHODS

We assessed parental confidence in vaccines through 9 telephone surveys in 6 and 11 provinces before, during, and after the two events. Provider confidence was assessed through in-person interviews following each event. Vaccine utilization was assessed using Immunization Information Management System data from township clinics.

RESULTS

In the early stages of each event, approximately 30% of parents indicated vaccine hesitancy and 18% said they would refuse routine immunization. Five and nine months after each event, hesitancy and refusal decreased, but not to pre-event levels. During the Shandong Vaccine Event, 49·1% of parents indicated refusal to use Category 2 vaccines; six months later, the rate was 32·8%. Use of HepB decreased by 21% during the first 2 weeks of the HepB Event and by 12·6% during the first 4 weeks of Shandong Vaccine Event, but returned to baseline in less than 3 months. Use of Category 2 vaccine decreased by 49·5% in the first 3 weeks of the Shandong Vaccine Event and by 28·7% 6 months later. After the Shandong Vaccine Event, 64% of clinicians held high confidence in routine immunization, lower than at baseline.

CONCLUSIONS

The two events caused mistrust, loss of confidence, and decreases in use of vaccines by parents and providers. In addition to ensuring immunization program integrity, effective communications and ongoing monitoring of vaccine use and confidence should be included to restore confidence and trust in vaccines.

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.

A cross-sectional study to describe and explore factors associated with measles immunisation and recording among cases linked to an outbreak, South West England, 2016

Following an outbreak of measles across South West England in 2016, the multi-agency outbreak control team suggested that immunisation history records collected for the health protection response may not be reliable. We undertook a cross-sectional study to compare measles immunisation records collected from outbreak cases on the case management system HPZone by the Health Protection Team with the full primary care record.

A total of 122 cases were reported. We identified 86.9% cases were not fully immunised and 5.7% had an unknown immunisation status. There were 14 cases whose primary care records did not match HPZone and 18 cases where primary care records were available and immunisation status was not documented in HPZone. Complex, non-linear associations were found between age and socioeconomic deprivation status of each case and having an incorrect HPZone record. Cases who resided in postcode areas of greater socioeconomic deprivation had statistically significantly higher odds of having been fully immunised. Only 13.3% of partially or unimmunised cases received an MMR immunisation following their onset of measles infection.

Collecting immunisation status from the full primary care record during acute management of measles cases may support improvements in control and prevention of further cases.

Measuring vaccination coverage better will help achieve disease control

Timely and accurate measurement of vaccination coverage is required to evaluate the success of vaccine programmes as well as identifying susceptible groups in order to better control disease. Estimating coverage requires knowledge of how many people are eligible for vaccination, and how many have received the vaccine. Achieving this presents a number of challenges in both high and low income settings. Investing in systems that record vaccination coverage better, as an integral part of vaccine strategies, will be a step towards better control of vaccine-preventable diseases.

Loss of confidence in vaccines following media reports of infant deaths after hepatitis B vaccination in China

BACKGROUND

China reduced hepatitis B virus (HBV) infection by 90% among children under 5 years old with safe and effective hepatitis B vaccines (HepB). In December 2013, this success was threatened by widespread media reports of infant deaths following HepB administration. Seventeen deaths and one case of anaphylactic shock following HBV vaccination had been reported.

METHODS

We conducted a telephone survey to measure parental confidence in HepB in eleven provinces at four points in time; reviewed maternal HBV status and use of HepB for newborns in birth hospitals in eight provinces before and after the event; and monitored coverage with hepatitis B vaccine and other programme vaccines in ten provinces.

RESULTS

HepB from the implicated company was suspended during the investigation, which showed that the deaths were not caused by HepB vaccination. Before the event, 85% respondents regarded domestic vaccines as safe, decreasing to 26.7% during the event. During the height of the crisis, 30% of parents reported being hesitant to vaccinate and 18.4% reported they would refuse HepB. Use of HepB in the monitored provinces decreased by 18.6%, from 53 653 doses the week before the event to 43 688 doses during the week that Biokangtai HepB was suspended. Use of HepB within the first day of life decreased by 10% among infants born to HBsAg-negative mothers, and by 6% among infants born to HBsAg-positive mothers. Vaccine refusal and HepB birth dose rates returned to baseline within 2 months; confidence increased, but remained below baseline.

CONCLUSIONS

The HBV vaccine event resulted in the suspension of a safe vaccine, which was associated with a decline of parental confidence, and refusal of vaccination. Suspension of a vaccine can lead to loss of confidence that is difficult to recover. Timely and credible investigation, accompanied by proactive outreach to stakeholders and the media, may help mitigate negative impact of future coincidental adverse events following immunization.

Extracting general practice data for timely vaccine coverage estimates: The England experience

In England, primary care providers use standardised coding systems to record health events such as vaccination as well as patient characteristics. This information can be automatically extracted to estimate coverage for vaccine programmes delivered through primary care, in the general population as well as in specific geographical, ethnic, age or clinical groups. This system provides timely vaccine coverage estimates as well as the flexibility to extract tailored data in order to directly inform a continuously evolving national vaccine programme. It is however limited by the quality and completeness of clinical coding in primary care. A centralised, individual-level register would however improve data quality, completeness and reliability and remains the gold standard.

Measles immunity gaps and the progress towards elimination: a multi-country modelling analysis

BACKGROUND

The persistent circulation of measles in both low-income and high-income countries requires a better characterisation of present epidemiological trends and existing immunity gaps across different sociodemographic settings. Serological surveys, which provide direct measures of population protection against the infection, are underexploited and often supply fragmentary estimates of population immunity. This study aims to investigate how measles immunity has changed over time across different socioeconomic settings, as a result of demographic changes and past immunisation policies.

METHODS

For this multi-country modelling analysis, we developed a transmission model to simulate measles circulation during the past 65 years in nine countries with distinct demographic and vaccination histories. The model was calibrated on historical serological data and used to estimate the reduction of disease burden as a result of vaccination and present age-specific residual susceptibility.

FINDINGS

Our model shows that estimated residual susceptibility to measles ranges from 3% in the UK to more than 10% in Kenya and Ethiopia. In high-income countries, such as Italy, Singapore, and South Korea, where routine first-dose administration produced more than 90% of immunised individuals, only about 20% of susceptible individuals are younger than 5 years. We also observed that the reduction in fertility that has occurred during the past decades in high-income countries has contributed to almost half of the reduction in measles incidence. In low-income countries, where fertility is high, the population is younger and routine vaccination has been suboptimum. Susceptible individuals are concentrated in early childhood, with about 60% of susceptible individuals in Ethiopia younger than 10 years. In these countries, Supplementary Immunization Activities (SIAs) were responsible for more than 25% of immunised individuals (up to 45% in Ethiopia), mitigating the consequences of suboptimum routine vaccination coverage.

INTERPRETATION

Future vaccination strategies in high-fertility countries should focus on increasing childhood immunisation rates, either by raising first-dose coverage or by making erratic SIAs more frequent and regular. Immunisation campaigns targeting adolescents and adults are required in low-fertility countries, where the susceptibility in these age groups will otherwise sustain measles circulation.

FUNDING

European Research Council.

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

INTRODUCTION

Following implementation of China's 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.

Waning Tdap Effectiveness in Adolescents

BACKGROUND AND OBJECTIVE

Because the effectiveness of diphtheria-tetanus-acellular pertussis (DTaP) vaccine wanes substantially after the fifth dose at ages 4 to 6 years, there is a growing cohort of adolescents who rely on tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) for protection against pertussis. Yet despite high Tdap vaccine coverage among adolescents, California experienced large pertussis outbreaks in 2010 and 2014. We investigated Tdap vaccine effectiveness (VE) and waning within Kaiser Permanente Northern California among adolescents exclusively vaccinated with DTaP vaccines.

METHODS

We modeled pertussis risk in relation to Tdap vaccination status among adolescents beginning on their 10th birthday. We estimated the hazard ratio (HR) for each subsequent year after Tdap compared with unvaccinated adolescents by using Cox regression, adjusting for calendar time, age, gender, race, and facility. We calculated VE as 1 - HR. We also treated time since Tdap vaccination as a continuous variable and estimated the change in the HR per 1-year increase since vaccination.

RESULTS

On the basis of 1207 pertussis cases, Tdap VE during the first year after vaccination was 68.8% (95% confidence interval [CI] 59.7% to 75.9%), decreasing to 8.9% (95% CI -30.6% to 36.4%) by ≥4 years after vaccination. Adolescents who were more remote from Tdap were significantly more likely to test positive for pertussis than were those vaccinated more recently (HR per year 1.35, 95% CI 1.22 to 1.50).

CONCLUSIONS

Routine Tdap did not prevent pertussis outbreaks. Among adolescents who have only received DTaP vaccines in childhood, Tdap provided moderate protection against pertussis during the first year and then waned rapidly so that litle protection remained 2-3 years after vaccination..