Registries: An essential tool for maximising the health benefits of immunisation in the 21st century

Tick-borne encephalitis vaccine uptake, effectiveness, and impact in Sweden from 2018 to 2022

Tick-borne encephalitis (TBE) is an increasing health threat in Sweden and elsewhere in Europe. TBE vaccination is commonly recommended in Sweden, but limited data are available on uptake, effectiveness, and impact of TBE vaccination. General population surveys conducted in 2019-2022 were used to estimated TBE vaccine uptake. TBE vaccine effectiveness (VE) was estimated using the screening method utilizing the surveys and public health TBE surveillance data, which predominately includes hospitalized TBE cases, from 2018 to 2022. Impact of TBE vaccination was calculated based on disease incidence and observed VE. In 2018-2022, 2,015 TBE cases were reported in Sweden; 82.8% (1,564/1,890) of cases with known TBE vaccination history were unvaccinated. Among persons surveyed from the general population with known vaccination history, 52.0% (11,562/22,247) were unvaccinated. Three dose VE against TBE was 89.0% (95% confidence interval 84.3-92.4). When stratified by age group, VE was 86.0% (55.7-95.6) in 1-15 years-of-age and 93.8% (87.5-96.9) in 16-49 years-of-age. In a conservative estimate, despite suboptimal compliance with TBE vaccination recommendations, vaccination averted an estimated thousand TBE cases, most resulting in hospitalization, in Sweden from 2018 to  2022. To prevent additional TBE cases in Sweden, enhanced efforts to increase TBE vaccine uptake and compliance to the TBE vaccination schedule are needed.

Onge JE, Shafazand S, Potter J. Vaccination in pregnancy: Healthcare provider attitudes and practices

OBJECTIVE

To assess provider attitudes and practices regarding vaccination in pregnancy to discern strategies to increase vaccination rates in pregnancy, given that in the USA, various healthcare organizations recommend that pregnant individuals be vaccinated against influenza, pertussis, and SARS-CoV-2, but vaccination rates among gravidas remain suboptimal across these vaccines.

METHODS

An Institutional Review Board-approved survey was disseminated to obstetric healthcare providers by email from June through October 2021. Questions assessed provider demographics, attitudes, and practices surrounding vaccination in pregnancy. A total of 192 providers consented, 179 initiated the survey, and 153 completed it entirely. Statistical software (SAS) was used to perform descriptive statistics.

RESULTS

All providers strongly agreed/agreed that all pregnant individuals should receive vaccines in pregnancy. Following patient vaccination consent, 13% reported needing to refer patients to alternative sites for vaccine administration. Following patient vaccination decline, 13% did not determine reasons for refusal, 30% did not re-counsel at subsequent visits, and 92% did not ask another staff member to counsel the patient.

CONCLUSION

Despite provider support for maternal immunization, uptake of vaccines in gravidas remains suboptimal, demonstrating a gap between provider recommendations and patient uptake. These data highlight opportunities for intervention regarding counseling and vaccine availability to increase vaccine uptake in pregnancy.

Characteristics associated with COVID-19 vaccine uptake among adults aged 50 years and above in England (8 December 2020-17 May 2021): a population-level observational study

OBJECTIVE

To determine characteristics associated with COVID-19 vaccine coverage among individuals aged 50 years and above in England since the beginning of the programme.

DESIGN

Observational cross-sectional study assessed by logistic regression and mean prevalence margins.

SETTING

COVID-19 vaccinations delivered in England from 8 December 2020 to 17 May 2021.

PARTICIPANTS

30 624 257/61 967 781 (49.4%) and 17 360 045/61 967 781 (28.1%) individuals in England were recorded as vaccinated in the National Immunisation Management System with a first dose and a second dose of a COVID-19 vaccine, respectively.

INTERVENTIONS

Vaccination status with COVID-19 vaccinations.

MAIN OUTCOME MEASURES

Proportion, adjusted ORs and mean prevalence margins for individuals not vaccinated with dose 1 among those aged 50-69 years and dose 1 and 2 among those aged 70 years and above.

RESULTS

Of individuals aged 50 years and above, black/African/Caribbean ethnic group was the least likely of all ethnic groups to be vaccinated with dose 1 of the COVID-19 vaccine. However, of those aged 70 years and above, the odds of not having dose 2 was 5.53 (95% CI 5.42 to 5.63) and 5.36 (95% CI 5.29 to 5.43) greater among Pakistani and black/African/Caribbean compared with white British ethnicity, respectively. The odds of not receiving dose 2 was 1.18 (95% CI 1.16 to 1.20) higher among individuals who lived in a care home compared with those who did not. This was the opposite to that observed for dose 1, where the odds of being unvaccinated was significantly higher among those not living in a care home (0.89 (95% CI 0.87 to 0.91)).

CONCLUSIONS

We found that there are characteristics associated with low COVID-19 vaccine coverage. Inequalities, such as ethnicity are a major contributor to suboptimal coverage and tailored interventions are required to improve coverage and protect the population from SARS-CoV-2.

Using observational epidemiology to evaluate COVID-19 vaccines: integrating traditional methods with new data sources and tools

Although clinical trials are necessary for vaccine approval, observational epidemiology will be required to evaluate the long-term effectiveness, safety, and population impacts of newly approved COVID-19 vaccines under real-world field conditions. In this commentary, I argue that a hybrid approach that combines new data sources and tools, including COVID-19 vaccine registries, with traditional epidemiological methods will be needed to evaluate COVID-19 vaccines using observational epidemiology. Wherever possible, primary data collection, active surveillance, and linkage with existing population-based cohorts should be leveraged to supplement secondary data sources and passive surveillance systems. Evidence-informed public health decision making around provincial COVID-19 immunization programs will need to account for potential biases, incomplete or conflicting information, and heterogeneity across subpopulations.

Suitability of databases in the Asia-Pacific for collaborative monitoring of vaccine safety

INTRODUCTION

Information regarding availability of electronic healthcare databases in the Asia-Pacific region is critical for planning vaccine safety assessments particularly, as COVID-19 vaccines are introduced. This study aimed to identify data sources in the region, potentially suitable for vaccine safety surveillance. This manuscript is endorsed by the International Society for Pharmacoepidemiology (ISPE).

METHODS

Nineteen countries targeted for database reporting were identified using published country lists and review articles. Surveillance capacity was assessed using two surveys: a 9-item introductory survey and a 51-item full survey. Survey questions related to database characteristics, covariate and health outcome variables, vaccine exposure characteristics, access and governance, and dataset linkage capability. Other questions collated research/regulatory applications of the data and local publications detailing database use for research.

RESULTS

Eleven databases containing vaccine-specific information were identified across 8 countries. Databases were largely national in coverage (8/11, 73%), encompassed all ages (9/11, 82%) with population size from 1.4 to 52 million persons. Vaccine exposure information varied particularly for standardized vaccine codes (5/11, 46%), brand (7/11, 64%) and manufacturer (5/11, 46%). Outcome data were integrated with vaccine data in 6 (55%) databases and available via linkage in 5 (46%) databases. Data approval processes varied, impacting on timeliness of data access.

CONCLUSIONS

Variation in vaccine data availability, complexities in data access including, governance and data release approval procedures, together with requirement for data linkage for outcome information, all contribute to the challenges in building a distributed network for vaccine safety assessment in the Asia-Pacific and globally. Common data models (CDMs) may help expedite vaccine safety research across the region.

The digital immunization system of the future: imagining a patient-centric, interoperable immunization information system

To ensure the effectiveness of increasingly complex immunization programs in upper-middle and high-income settings, comprehensive information systems are needed to track immunization uptake at individual and population levels. The maturity of cloud systems and mobile technologies has created new possibilities for immunization information systems. In this paper, we describe a vision for the next generation of digital immunization information systems for upper-middle and high-income settings based on our experience in Canada. These systems center on the premise that the public is engaged and informed about the immunization process beyond their interaction with primary care, and that they will be a contributor and auditor of immunization data. The digital immunization system of the future will facilitate reporting of adverse events following immunization, issue digital immunization receipts, permit identification of areas of need and allow for delivery of interventions targeting these areas. Through features like immunization reminders and targeted immunization promotion campaigns, the system will reduce many of the known barriers that influence immunization rates. In light of the global COVID-19 pandemic, adaptive digital public health information systems will be required to guide the rollout and post-market surveillance of the SARS-CoV-2 vaccine.

Estimating age-specific vaccine effectiveness using data from a large measles outbreak in Berlin, Germany, 2014/15: evidence for waning immunity

BackgroundMeasles elimination is based on 95% coverage with two doses of a measles-containing vaccine (MCV2), high vaccine effectiveness (VE) and life-long vaccine-induced immunity. Longitudinal analysis of antibody titres suggests existence of waning immunity, but the relevance at the population-level is unknown.AimWe sought to assess presence of waning immunity by estimating MCV2 VE in different age groups (2-5, 6-15, 16-23, 24-30 and 31-42 years) in Berlin.MethodsWe conducted a systematic literature review on vaccination coverage and applied the screening-method using data from a large measles outbreak (2014/15) in Berlin. Uncertainty in input variables was incorporated by Monte Carlo simulation. In a scenario analysis, we estimated the proportion vaccinated with MCV2 in those 31-42 years using VE of the youngest age group, where natural immunity was deemed negligible.ResultsOf 773 measles cases (median age: 20 years), 40 had received MCV2. Average vaccine coverage per age group varied (32%-88%). Estimated median VE was  > 99% (95% credible interval (CrI): 98.6-100) in the three youngest age groups, but lower (90.9%, 95% CrI: 74.1-97.6) in the oldest age group. In the scenario analysis, the estimated proportion vaccinated was 98.8% (95% CrI: 96.5-99.8).ConclusionVE for MCV2 was generally high, but lower in those aged 31-42 years old. The estimated proportion with MCV2 should have led to sufficient herd immunity in those aged 31-42 years old. Thus, lower VE cannot be fully explained by natural immunity, suggesting presence of waning immunity.

The impact of time since vaccination and study design on validity in parental recall of childhood vaccination status in the All Our Families cohort

INTRODUCTION

Parental reporting of childhood vaccination status is often used for policy and program evaluation and research purposes. Many factors can bias parental reporting of childhood vaccination status, however, to our knowledge, no analysis has assessed whether time since vaccination impacts reporting accuracy. Therefore, using the Calgary electronic vaccine registry (PHANTIM) as the gold standard, we aimed to test the accuracy of parental reporting of childhood vaccination status at three different time-points since vaccination.

METHODS

The All Our Families (AOF) cohort study asked parents to report their child's 2, 4, 6, 12 and 18 month vaccines (vaccination time-point) on questionnaires given when the child was 1, 2 and 3 years of age (survey time-point). We linked the AOF parental reporting of vaccination status to the PHANTIM registry and calculated the percent agreement and difference in coverage estimates between PHANTIM and AOF at each vaccination and survey time-point combination. Furthermore, we measured the sensitivity and specificity, and negative (NPV) and positive predictive values (PPV) of parental vaccine recall across time.

RESULTS

AOF parent reports of coverage rates were consistently higher than the PHANTIM estimates. While we saw significant differences in percent agreement for certain vaccination time-points, we saw no consistent directional difference by survey time-point, suggesting that parental accuracy did not change with time. We found a uniformly high sensitivity across all vaccination and survey time-points, and no consistent patterns in the specificity, PPV and NPV results.

CONCLUSION

Time since vaccination may not be the most important consideration when designing and implementing a vaccination survey. Other factors that may contribute to the bias associated with parental reporting of vaccination status include the complexity of the vaccine schedule, schedule changes over time, and the wording and structure of the questionnaires.

Using Routine Data Sources to Feed an Immunization Information System for High-Risk Patients-A Pilot Study

Background

Vaccine-preventable diseases among high-risk patients are a public health priority in high-income countries. Most national immunization programs have included vaccination recommendations for these population groups but they remain hard-to-reach and coverage data are poorly available. In a pilot study, we developed and tested an automated approach for identifying individuals with underlying medical conditions to feed an immunization information system (IIS).

Methods

We reviewed published recommendations on medical conditions that indicate vaccination against influenza, pneumococcal disease, meningococcal disease, hepatitis A, and hepatitis B. For each medical condition, we identified the International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis and procedure codes, the user fee exempt codes and the Anatomical Therapeutic Chemical Classification System codes and we reported these data in correspondence tables. Using these tables, we extracted three lists of patients recorded in three current data sources between 2001 and 2010 in the Apulia region of Italy: the hospital discharge registry, the user fee exempt registry, and the drug prescription registry. Using a unique personal identification number, we linked these three lists of patients with the regional IIS (2012 database), obtaining a list of patients with chronic diseases eligible for vaccination. We tested completeness, sensitivity, and positive predictive value (PPV) of this approach by asking a sample of 28 general practitioners (GPs) to evaluate the matching between a sublist of patients with clinical recommendations for influenza vaccination and the GPs individual subjects medical records.

Results

We included a total of 1,204,496 subjects with underlying medical conditions eligible to receive any of the aforementioned vaccinations. Of these, 9% were identified in all three data sources, 18% in two sources, and 73% in one source. The completeness of this automated process in identifying GPs high-risk patients eligible for influenza vaccination was 88.9% [95% confidence intervals (95% CI): 88.1–89.8%], with a sensitivity of 69.2% (95% CI: 67.7–70.6%) and a PPV of 85.7% (95% CI: 84.4–86.8%).

Conclusion

The high completeness of the methodology used for identifying high-risk patients in current data sources encouraged us to apply this approach for feeding the regional IIS.