Estimate Vaccination Coverage Research Articles

Influenza Vaccination Coverage Among Medicare Fee-for-Service Beneficiaries

Influenza vaccination is the best prevention strategy to protect against influenza infection. Determining accurate influenza vaccination coverage is critical. This study assesses the concordance between self-reported and claimed-based influenza vaccination coverage and examines vaccination disparities in the U.S. Data from the 2016-2019 Medicare Current Beneficiary Survey linked to survey participants' influenza vaccination claims were analyzed in 2022. The study population included survey participants aged ≥65 years and enrolled in a Medicare fee-for-service plan. Sensitivity, specificity, kappa statistics, and net bias (the difference between the estimated vaccination coverage based on survey and claims data) were reported. Associations between receipt of influenza vaccine and beneficiaries' characteristics and sex, racial and ethnic, and urban‒rural disparities in influenza vaccination were examined using logistic regressions. The analysis included 20,854 beneficiaries. Claimed-based vaccination coverage was 60.0%, and survey-based coverage was 76.3%. The net bias was 16.3 percentage points, and kappa statistic indicated moderate data agreement. The sensitivity of self-reported influenza vaccination was 98.7%, and the specificity was 57.4%. Net bias was high among male, non-Hispanic Black and Hispanic beneficiaries, and rural residents. Sex, racial and ethnic, and urban‒rural disparities in influenza vaccination were noticeably smaller according to the survey than claims data. The level of data agreement differed by beneficiaries' characteristics and was low among males, racial and ethnic minority groups, and rural residents.

EPH96 Infant Immunization Coverage in a Colombian Poor Municipality in the Post-Conflict Era

Colombia has an expanded program of immunization of >22 biologics mainly for younger than 6 years old. We aimed to estimate vaccination coverage in children under 6 years old in San Jacinto (Bolivar), in a post-conflict and COVID-19 pandemic scenario.

Accuracy of mother’s reporting on child immunization in Yemen between 2012 and 2013

There is a complex interaction between infectious diseases and child nutritional status as infections usually entail some nutritional setback and vice versa. Therefore, vaccination against childhood infectious diseases is an important preventive measure against malnutrition itself, playing a key role in reducing child mortality. However, whereas referring to vaccination coverage it is crucial to have it clear how this coverage is measured, once it may vary considerably depending on the source of information. While child vaccination status is obtained from medical records in developed countries, in developing countries, they are mostly taken from vaccination cards and/or mothers’ reports. Nevertheless, some researchers have come to diverse conclusions in terms of the accuracy of parents’ reports. Based on a rich longitudinal household survey available for Yemen collected in 2012 – 2013, we find that although mothers’ reports should not be discarded when estimating vaccination coverage (otherwise, coverage would be extremely overestimated), this information should be used with caution.

Influenza Vaccination Among Pregnant Women: Self-report Compared With Vaccination Data From Electronic Health Records, 2018-2020 Influenza Seasons.

Having accurate influenza vaccination coverage estimates can guide public health activities. The objectives of this study were to (1) validate the accuracy of electronic health record (EHR)-based influenza vaccination data among pregnant women compared with survey self-report and (2) assess whether survey respondents differed from survey nonrespondents by demographic characteristics and EHR-based vaccination status. This study was conducted in the Vaccine Safety Datalink, a network of 8 large medical care organizations in the United States. Using EHR data, we identified all women pregnant during the 2018-2019 or 2019-2020 influenza seasons. Surveys were conducted among samples of women who did and did not appear vaccinated for influenza according to EHR data. Separate surveys were conducted after each influenza season, and respondents reported their influenza vaccination status. Analyses accounted for the stratified design, sampling probability, and response probability. The survey response rate was 50.5% (630 of 1247) for 2018-2019 and 41.2% (721 of 1748) for 2019-2020. In multivariable analyses combining both survey years, non-Hispanic Black pregnant women had 3.80 (95% CI, 2.13-6.74) times the adjusted odds of survey nonresponse; odds of nonresponse were also higher for Hispanic pregnant women and women who had not received (per EHR data) influenza vaccine during current or prior influenza seasons. The sensitivity, specificity, and positive predictive value of EHR documentation of influenza vaccination compared with self-report were ≥92% for both survey years combined. The negative predictive value of EHR-based influenza vaccine status was 80.5% (95% CI, 76.7%-84.0%). EHR-based influenza vaccination data among pregnant women were generally concordant with self-report. New data sources and novel approaches to mitigating nonresponse bias may be needed to enhance influenza vaccination surveillance efforts.

Estimation of infant vaccination coverage at national and region level in Ethiopia: a cross-sectional study.

Introductionan increasing trend of routine immunization performance has generally been observed over the past decade in Ethiopia. However, inconsistencies were observed over time and among different sources of data. This review analyzed systematically data from various sources and produced regional and national coverage estimates for antigens offered in the infant immunization program in Ethiopia.Methodswe collated data from administrative reports, population-based surveys and other sources to produce annual estimates of vaccination coverage. We obtained relevant data for each of the 9 Regional States and 2 city administrations, for the period 2007-2016. Region level estimates were produced based on survey results, interpolation between or extrapolation. We aggregated the resulting region level estimates, using a population-weighted approach, to give national estimates.Resultswe found that the national Penta 3 coverage of Ethiopia increased from 59% in 2007 to 71% in 2016. For the 110 vaccination estimates produced at region level, 71 were based on interpolation or extrapolation from empirical anchor points; 18% were based on surveys and 17% were based on administrative data.Conclusionwhile we recognize the critical importance of improving the quality of information on vaccination coverage from administrative reporting systems, we are also cognizant of the expected continued need for region level surveys and improved rapid-monitoring exercises.

COVID-19 vaccination coverage and associated factors in seasonal fruit workers in Lleida

ObjectivesSeasonal fruit workers are a high-risk group for SARS-COV-2 infection. We aimed to estimate vaccination coverage and factors associated with vaccination in seasonal fruit workers. MethodsWe carried out an anonymous survey of seasonal fruit workers in the 2021 campaign in Baix Segria region and Lleida city (Spain) on vaccination, knowledge and attitudes about the COVID-19 vaccine. Univariate and bivariate descriptive analyses were performed comparing vaccinated versus non-vaccinated. Multivariate analysis was performed using to assess factors associated to vaccination uptake. ResultsWe included 286 seasonal workers. The prevalence of confirmed COVID-19 background was 39.5% and overall vaccination coverage was 78.7%. Factors associated with vaccination were age (aOR = 0.96; 95% CI: 0.94–0.99), good knowledge of disease (aOR = 1.87; 95% CI : 1.01–3.47) and having a high-perceived vaccine effectiveness (aOR = 2.94; 95% CI : 1.50–5.73). High vaccination coverage in workers was associated to knowledge (OR = 3.69; 95% CI: 1.61–8.48), safe transport (OR = 2.84; 95% CI: 1.40–5.76) and appropriate housing (OR = 2.62; 95% CI: 1.25–5.46) as important non-pharmacological measures to reduced transmission. ConclusionThe study confirms the high prevalence of COVID-19 history and moderate vaccination coverage in seasonal fruit workers. Health education programs to improve knowledge about COVID-19 and its vaccination can help improve vaccination uptake.

Evaluation of influenza vaccination coverage in Shanghai city during the 2016/17 to 2020/21 influenza seasons

ABSTRACT Influenza is a common infectious disease resulting in substantial morbidity and mortality globally. The most effective strategy for preventing influenza is annual vaccination; however, the coverage rate of the influenza vaccine in Shanghai has not been well explored or reported. Therefore, this study aimed to determine coverage with the influenza vaccine and access trends in Shanghai city; data from Shanghai immunization information system was analyzed to estimate vaccination coverage during 2016–2017 through 2020–2021 influenza seasons. Vaccination coverage by age groups, immigration status, and districts was accessed. The influenza vaccination coverage (at least one dose) for 2016/2017 to 2020/2021 influenza seasons was 10.8‰ (95‰ CI: 10.7–10.8), 12.3‰ (95‰ CI: 12.3–12.4), 10.1‰ (95‰ CI: 10.0–10.1), 20.1‰ (95‰ CI: 20.0–20.2) and 50.8‰ (95‰ CI: 50.7–50.8) respectively. Although we found significantly higher vaccination coverage in females, children from 6 months to 17 years, and residents, it is still low in all subgroups of the population in Shanghai. Therefore, taking effective steps to promote influenza vaccination in Shanghai is recommended.

How to estimate health service coverage in 58 districts of Benin with no survey data: Using hybrid estimation to fill the gaps.

The global movement to use routine information for managing health systems to achieve the Sustainable Development Goals, relies on administrative data which have inherent biases when used to estimate coverage with health services. Health policies and interventions planned with incorrect information can have detrimental impacts on communities. Statistical inferences using administrative data can be improved when they are combined with random probability survey data. Sometimes, survey data are only available for some districts. We present new methods for extending combined estimation techniques to all districts by combining additional data sources. Our study uses data from a probability survey (n = 1786) conducted during 2015 in 19 of Benin's 77 communes and administrative count data from all of them for a national immunization day (n = 2,792,803). Communes are equivalent to districts. We extend combined-data estimation from 19 to 77 communes by estimating denominators using the survey data and then building a statistical model using population estimates from different sources to estimate denominators in adjacent districts. By dividing administrative numerators by the model-estimated denominators we obtain extrapolated hybrid prevalence estimates. Framing the problem in the Bayesian paradigm guarantees estimated prevalence rates fall within the appropriate ranges and conveniently incorporates a sensitivity analysis. Our new methodology, estimated Benin's polio vaccination rates for 77 communes. We leveraged probability survey data from 19 communes to formulate estimates for the 58 communes with administrative data alone; polio vaccination coverage estimates in the 58 communes decreased to ranges consistent with those from the probability surveys (87%, standard deviation = 0.09) and more credible than the administrative estimates. Combining probability survey and administrative data can be extended beyond the districts in which both are collected to estimate coverage in an entire catchment area. These more accurate results will better inform health policy-making and intervention planning to reduce waste and improve health in communities.

Evaluating vaccination coverage and timeliness in American Indian/Alaska Native and non-Hispanic White children using state immunization information system data, 2015-2017

Comprehensive estimates of vaccination coverage and timeliness of vaccine receipt among American Indian/Alaska Native (AI/AN) children in the United States are lacking. This study’s objectives were to quantify vaccination coverage and timeliness, as well as the proportion of children with specific undervaccination patterns, among AI/AN and non-Hispanic White (NHW) children ages 0–24 months in Montana, a large and primarily rural U.S. state. Data from Montana’s immunization information system (IIS) for children born 2015–2017 were used to calculate days undervaccinated for all doses of seven recommended vaccine series. After stratifying by race/ethnicity, up-to-date coverage at key milestone ages and the proportion of children demonstrating specific patterns of undervaccination were reported. Among n = 3,630 AI/AN children, only 23.1% received all recommended vaccine doses on-time (i.e., zero days undervaccinated), compared to 40.4% of n = 18,022 NHW children (chi-square p < 0.001). A greater proportion of AI/AN children were delayed at each milestone age, resulting in lower overall combined 7-vaccine series completion, by age 24 months (AI/AN: 56.6%, NHW: 64.3%, chi-square p < 0.001). As compared with NHW children, a higher proportion of AI/AN children had undervaccination patterns suggestive of structural barriers to accessing immunization services and delayed starts to vaccination. More than three out of four AI/AN children experienced delays in vaccination or were missing doses needed to complete recommended vaccine series. Interventions to ensure on-time initiation of vaccine series at age 2 months, as well initiatives to encourage completion of multi-dose vaccine series, are needed to reduce immunization disparities and increase vaccination coverage among AI/AN children in Montana.

Influenza epidemiology in patients admitted to sentinel Australian hospitals in 2019: the Influenza Complications Alert Network (FluCAN).

Influenza is a common cause of acute respiratory infection, and is a major cause of morbidity and mortality. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza during the 2019 influenza season. The Influenza Complications Alert Network (FluCAN) is a sentinel hospital-based surveillance program that operates at sites in all jurisdictions in Australia. Cases were defined as patients hospitalised at any of the 17 sentinel hospitals with influenza confirmed by nucleic acid detection. Data were also collected on a frequency matched control group of influenza-negative patients admitted with acute respiratory infection. During the period 1 April to 31 October 2019 (the 2019 influenza season), there were 4,154 patients admitted with confirmed influenza to one of 17 FluCAN sentinel hospitals. Of these, 44% were elderly (≥ 65 years), 21% were children (< 16 years), 7.7% were Aboriginal and Torres Strait Islander peoples, 1.7% were pregnant and 73% had chronic comorbidities. Most admissions were due to influenza A infection (85%). Estimated vaccine coverage was 75% in the elderly, 49% in non-elderly adults with medical comorbidities, and 27% in young children (< 5 years). The estimated vaccine effectiveness in the target adult population was 42% (95% confidence interval [95% CI]: 36%, 49%). There were a larger number of hospital admissions detected with confirmed influenza in this national observational surveillance system in 2019 than in 2018.

A tool for early estimation of influenza vaccination coverage in Spanish general population and healthcare workers in the 2018\u201319 season: the Grip\xf3metro

AsbtractBackgroundElectronic vaccine registries are not yet widely established. There is a need to real-time monitor influenza vaccine coverage, which may raise awareness to risk groups and professionals, and eventually allow to adopt tailored measures during the vaccination campaign. To evaluate the utility of the “Gripómetro”, a demographic study designed to monitor national and regional influenza vaccine coverage on a weekly basis in Spain.MethodsQuantitative study based on surveys of the Spanish population between 18–80 years and a sample of primary care doctors and nurses randomly selected. Pre-proportional fixation has been established by Autonomous Communities and age group to guarantee the representativeness of all the autonomies.ResultsInterviews were conducted in 3400 households of general population and 807 respondents among health care professionals. We found that the results of influenza vaccination coverage in the population ≥ 65 years obtained by the Gripómetro for 2018–2019 season were mostly comparable with the official data presented by the Ministry of Health after the end of the vaccination campaign.ConclusionsThe Gripómetro is a robust research method that provides real-time data and trends for influenza vaccine coverage along with other useful information related to vaccination such as intention to vaccinate, motivation and barriers to vaccination.

Disparities in human papillomavirus vaccination coverage in the United States, National Health and Nutrition Examination Survey, January 2017–March 2020

BackgroundWe assessed disparities in HPV vaccination coverage by sociodemographic characteristics in the United States. MethodsUsing 2017-March 2020 National Health and Nutrition Examination Survey data, we estimated vaccination coverage of ≥ 1 dose of HPV vaccine by race/ethnicity and poverty, insurance, and nativity status for females and males aged 9–14, 15–19, and 20–29 years. ResultsAmong those aged 9–14 years, coverage among non-Hispanic Black (NHB), Hispanic, and non-Hispanic Asian (NHA) females (40.0%, 33.6%, 34.0%) and males (27.1%, 35.3%, 30.9%) was higher than non-Hispanic White (NHW) females (26.5%) and males (25.2%). Among those aged 15–19 and 20–29 years, coverage varied among NHB, Hispanic, and NHA compared to NHW females and was lower among NHB, Hispanic, and NHA than NHW males. Coverage was lower among uninsured than insured in most comparisons. ConclusionsHPV vaccination coverage varied by race/ethnicity and other characteristics. Efforts are needed to increase HPV vaccination coverage in all populations.

Impact of the COVID-19 pandemic on Bordetella pertussis infections in England

BackgroundIn March 2020, England went into its first lockdown in response to the COVID-19 pandemic. Restrictions eased temporarily, followed by second and third waves in October 2020 and January 2021. Recent data showed that the COVID-19 pandemic resulted in reduced transmission of some invasive diseases. We assess the impact of the COVID-19 pandemic on pertussis incidence and on the immunisation programme in England.MethodsWe assessed trends in pertussis cases from 2012 to 2020 by age group and month. Incidence from the time that England eased its initial lockdown measures in July 2020 through to summer 2021 was calculated and the incidence rate ratios of pertussis cases from five years prior to the pandemic (July 2014 – June 2019) compared to the same time period during the pandemic (July 2020 – June 2021). Vaccine coverage estimates for pertussis containing vaccines were reviewed for the maternal and childhood programmes.ResultsA substantial decline in pertussis cases was observed from April 2020 onwards, marking the lowest number of cases in the last decade. Pertussis incidence dropped in all age groups, particularly among infants less than one year old (0.50 / 100,000 during July 2020 to June 2021 compared to 24.49/ 100,000 from July 2014 to June 2019). The incidence rate ratio was 0.02 (95% CI 0.01 to 0.02) for July 2014 to June 2019 (pre-pandemic) compared to the pandemic period of July 2020 to June 2021. None of the cases had a co-infection with SARS-CoV-2. Vaccine coverage for infants born between January to March 2020 with three doses of pertussis vaccine by 12 months of age decreased by 1.1% points compared to infants born between January to March 2019 (91.6% and 92.7%, respectively). Prenatal pertussis coverage for the 2020 to 2021 financial year was 2.7% points lower than the year prior to the pandemic (70.5% and 76.8%, respectively).ConclusionsLockdown measures due to the COVID-19 pandemic have had a significant impact on pertussis transmission. With the easing of restrictions it is important to continue monitoring pertussis cases in England alongside coverage of the maternal and childhood immunisation programmes.

Exploring vaccination coverage and attitudes of health care workers towards influenza vaccine in Cyprus

Seasonal influenza is a major public health problem. Nosocomial influenza is particularly concerning as it may affect patients at high risk for complications. Unvaccinated health care workers (HCWs) are an important source of nosocomial influenza and therefore a priority target group for vaccination. Despite the fact that some European countries have high coverage rates such as UK (76.8% in season 2020/21), others continue to have low coverage rates for influenza vaccines. This study aims to estimate vaccination coverage in HCWs in Cyprus, an island country located in the Eastern Mediterranean region and describe their attitudes towards influenza vaccination. MethodsThis is a questionnaire based, nation-wide study assessing flu vaccination coverage in 2019–2020 and attitudes related to vaccination acceptance, of 962 HCWs in both public and private health care facilities. Multivariable logistic regression was used to investigate factors associated with flu vaccination status. ResultsFlu vaccination coverage was estimated as 31.8%. The top two reasons for getting vaccinated were to protect their family (81.4%) and themselves (77.4%). The top two reasons for not getting immunised, besides “no particular reason” (25.7%), included disbelief for vaccine effectiveness (21.5%) and safety (29.3%). The regression model showed that doctors compared to nurses had 10 times the odds of being vaccinated. Other factors positively associated with flu vaccination were encouragement by the supervisor, having sufficient knowledge on flu and flu vaccination and easy access to vaccination. A percentage of 54.8% of participants stated that COVID-19 pandemic strongly or somewhat influenced their decision to get vaccinated. ConclusionFlu vaccination coverage in HCWs in Cyprus is rather low, similar to some other European countries. Barriers and facilitators in this study can be considered in strategies to increase flu vaccination uptake. Such questionnaire-based surveys should be repeated in order to evaluate effectiveness of targeted vaccination campaigns.

Rural-Urban Differences in Influenza Vaccination Among Adults in the United States, 2018-2019.

Objectives. To provide adjusted rates of self-reported receipt of the influenza vaccine in the 2018-2019 flu season among adults in large metropolitan, medium and small metropolitan, and nonmetropolitan areas of the United States by age group, gender, and race. Methods. We queried the 2019 National Health Interview Survey for respondents aged 18 years and older. To provide national estimates of influenza vaccination coverage, we performed sample-weighted multivariable logistic regressions and predicted marginal modeling while adjusting for age, gender, race/ethnicity, and urban-rural household designation. Results. After weighting, 48.1%, 46.2%, and 43.6% of adults from large metropolitan, small and medium metropolitan, and nonmetropolitan areas, respectively, received the influenza vaccine. Additionally, there was a trend toward declining influenza vaccination status from large metropolitan to rural areas in all age groups, both genders, and multiple racial/ethnic groups. Conclusions. Self-reported influenza vaccination rates were lower in rural than in urban areas among adults of all age groups and both genders. Using community leaders for health promotion, augmentation of the community health care workforce, and provision of incentives for providers to integrate influenza vaccination in regular visits may expand influenza vaccine coverage. (Am J Public Health. 2022;112(2):304-307. https://doi.org/10.2105/AJPH.2021.306575).

Toward the calibration of serological assays using sera collected from cattle and sheep following a single dose of foot-and-mouth disease vaccine.

Background and Aim:Serological assays are widely used to monitor the performance of foot-and-mouth disease (FMD) vaccines to estimate vaccination coverage and to ensure that vaccinated animals generate adequate immune responses. This study aimed to measure the FMD virus (FMDV)-specific responses in cattle and sheep after a single dose of a trivalent FMD vaccine containing serotypes A, O, and Asia-1, and to use these sera to calibrate virus neutralization tests (VNTs) and serotype-specific serological enzyme-linked immunoassays (ELISAs) that can measure post-vaccination responses.Materials and Methods:Sera were collected from cattle (n=10) and sheep (n=10) on 0, 21, and 56 days after immunization with an imported aqueous formulated FMD vaccine. These samples were tested by VNT using field FMDV isolates that are representative of the epidemiological risks in Central Asia (A/ASIA/Iran-05, A/ASIA/GVII, O/ME-SA/Ind-2001, O/SEA/Mya-98, O/ME-SA/PanAsia, and Asia-1 Shamir). Heterologous VNT antibody responses were compared to those measured using commercial FMDV-specific ELISAs for serotypes O, A, and Asia 1.Results:Administration of the FMD vaccine increased FMDV-specific antibody titers for both species in sera collected on day 21, but these elevated titers were short-lived and were decreased by day 56.Conclusion:These results highlight the short duration of immunity with a single dose of this aqueous vaccine and motivate further studies to assess immune responses in cattle and small ruminants after a two-dose course vaccination schedule. Further comparative data for VNT and serotype-specific ELISAs are needed to define cutoffs that can be used to monitor post-vaccination immune responses in low-containment laboratories where it is not possible to handle live FMDVs.

Social clustering of unvaccinated children in schools in the Netherlands.

For the measles-mumps-rubella (MMR) vaccine, the World Health Organization-recommended coverage for herd protection is 95% for measles and 80% for rubella and mumps. However, a national vaccine coverage does not reflect social clustering of unvaccinated children, e.g. in schools of Orthodox Protestant or Anthroposophic identity in The Netherlands. To fully characterise this clustering, we estimated one-dose MMR vaccination coverages at all schools in the Netherlands. By combining postcode catchment areas of schools and school feeder data, each child in the Netherlands was characterised by residential postcode, primary and secondary school (referred to as school career). Postcode-level vaccination data were used to estimate vaccination coverages per school career. These were translated to coverages per school, stratified by school identity. Most schools had vaccine coverages over 99%, but major exceptions were Orthodox Protestant schools (63% in primary and 58% in secondary schools) and Anthroposophic schools (67% and 78%). School-level vaccine coverage estimates reveal strong clustering of unvaccinated children. The school feeder data reveal strongly connected Orthodox Protestant and Anthroposophic communities, but separated from one another. This suggests that even at a national one-dose MMR coverage of 97.5%, thousands of children per cohort are not protected by herd immunity.

The Food and Drug Administration Biologics Effectiveness and Safety Initiative Facilitates Detection of Vaccine Administrations From Unstructured Data in Medical Records Through Natural Language Processing.

Introduction: The Food and Drug Administration Center for Biologics Evaluation and Research conducts post-market surveillance of biologic products to ensure their safety and effectiveness. Studies have found that common vaccine exposures may be missing from structured data elements of electronic health records (EHRs), instead being captured in clinical notes. This impacts monitoring of adverse events following immunizations (AEFIs). For example, COVID-19 vaccines have been regularly administered outside of traditional medical settings. We developed a natural language processing (NLP) algorithm to mine unstructured clinical notes for vaccinations not captured in structured EHR data.Methods: A random sample of 1,000 influenza vaccine administrations, representing 995 unique patients, was extracted from a large U.S. EHR database. NLP techniques were used to detect administrations from the clinical notes in the training dataset [80% (N = 797) of patients]. The algorithm was applied to the validation dataset [20% (N = 198) of patients] to assess performance. Full medical charts for 28 randomly selected administration events in the validation dataset were reviewed by clinicians. The NLP algorithm was then applied across the entire dataset (N = 995) to quantify the number of additional events identified.Results: A total of 3,199 administrations were identified in the structured data and clinical notes combined. Of these, 2,740 (85.7%) were identified in the structured data, while the NLP algorithm identified 1,183 (37.0%) administrations in clinical notes; 459 were not also captured in the structured data. This represents a 16.8% increase in the identification of vaccine administrations compared to using structured data alone. The validation of 28 vaccine administrations confirmed 27 (96.4%) as “definite” vaccine administrations; 18 (64.3%) had evidence of a vaccination event in the structured data, while 10 (35.7%) were found solely in the unstructured notes.Discussion: We demonstrated the utility of an NLP algorithm to identify vaccine administrations not captured in structured EHR data. NLP techniques have the potential to improve detection of vaccine administrations not otherwise reported without increasing the analysis burden on physicians or practitioners. Future applications could include refining estimates of vaccine coverage and detecting other exposures, population characteristics, and outcomes not reliably captured in structured EHR data.

Validity of maternal recall for estimating childhood vaccination coverage – Evidence from Nigeria

BackgroundVaccination coverage surveys in low- and middle-income countries typically estimate vaccination coverage using data from vaccination cards, parental recall, or a combination of the two. However, these surveys are often complicated by the pervasive absence of vaccination cards, forcing researchers to rely on parental recall. We assessed the validity of mothers’ recall against home-based vaccination cards using data from a community-based household survey in Nigeria. MethodsA cross-sectional survey of 1,254 mothers of children aged 12–23 months was performed in Enugu State, Nigeria in July 2020. Data on vaccination status for BCG, OPV, DPT, Measles, Yellow fever, and Vitamin A supplement were collected using two data sources: home-based vaccination cards and mothers’ recall. We evaluated the level of agreement between the two data sources; estimated the sensitivity and specificity of mothers’ recalls; and computed multivariable regression models to identify socio-demographic factors associated with mothers’ recall bias. ResultsOut of 1,254 mothers interviewed, 578 (46.1%) mothers with vaccination cards were included in this analysis. Vaccination coverage levels were generally similar across data sources, though recall-based data generally underestimated the coverage. The level of agreement between the two data sources was high (≥91.0% for all vaccine types) with recall bias due to under-reporting generally higher than recall bias due to over-reporting. The sensitivity of parental recalls was high for all vaccine types, while the specificity was low across vaccine types. Across all vaccines, mothers recall bias was significantly associated with the rural residence and not receiving postnatal care. ConclusionIn the absence of vaccination cards, mothers’ recall of their children’ vaccination status for BCG, OPV, DPT, Measles, Yellow fever and Vitamin A is a valid instrument for estimating childhood vaccination coverage in this setting in Nigeria. However, additional research is needed to confirm these findings at higher sub-national and national levels.

A multi-country investigation of influenza vaccine coverage in pregnant individuals, 2010–2016

BackgroundMany countries recommend influenza vaccination during pregnancy. Despite this recommendation, influenza vaccine among pregnant individuals remains under-utilized and uptake varies by country. Factors associated with influenza vaccine uptake during pregnancy may also vary across countries. MethodsAs members of the Pregnancy Influenza Vaccine Effectiveness Network (PREVENT), five sites from four countries (Australia, Canada, Israel, and the United States) retrospectively identified cohorts of individuals aged 18–50 years who were pregnant during pre-defined influenza seasons. Influenza vaccine coverage estimates were calculated for the 2010–11 through 2015–16 northern hemisphere and the 2012 through 2015 southern hemisphere influenza seasons, by site. Sites used electronic health records, administrative data, and immunization registries to collect information on pregnancy, health history, demographics, and vaccination status. Each season, vaccination coverage was calculated as the percentage of individuals who received influenza vaccine among the individuals in the cohort that season. Characteristics were compared between those vaccinated and unvaccinated, by site. ResultsMore than two million pregnancies were identified over the study period. Influenza vaccination coverage ranged from 5% to 58% across sites and seasons. Coverage increased consistently over the study period at three of the five sites (Western Australia, Alberta, and Israel), and was highest in all seasons at the United States study site (39–58%). Associations with vaccination varied by country and across seasons; where available, parity >0, presence of a high-risk medical condition, and urban residence were consistently associated with increased likelihood of vaccination. ConclusionsThough increasing, uptake of influenza vaccine among pregnant individuals remains lower than recommended. Coverage varied substantially by country, suggesting an ongoing need for targeted strategies to improve influenza vaccine uptake in this population.