Incomplete HPV Vaccination among Individuals Aged 27-45 Years in the United States: A Mixed-Effect Analysis of Individual and Contextual Factors

Background: In the United States, the human papillomavirus (HPV) vaccine is approved for use in individuals up to age 45. Individuals 15 years and older require three doses of the vaccine to complete the recommended dosing series. Incomplete HPV vaccination rates (i.e., one or two doses) among those over age 26, however, remain high. This study examined the independent effects of individual- and neighborhood-level factors on incomplete HPV vaccination rates in the United States (U.S.) among those aged 27-45 years. Methods: This retrospective cohort study used administrative data from Optum's de-identified Clinformatics® Data Mart Database to identify individuals aged 27-45 years who received one or more doses of HPV vaccine between July 2019 and June 2022. Multilevel multivariable logistic regression models were applied to the data on 7662 individuals identified as being fully or partially vaccinated against HPV, nested within 3839 neighborhoods across the U.S. Results: Approximately half of the patients in this study (52.93%) were not completely vaccinated against HPV. After adjusting for all other covariates in the final model, being older than 30 years old decreased the odds of not completing the HPV vaccine series. Participants living in South-region neighborhoods of the U.S. had enhanced odds of not completing the vaccine series compared with those residing in Northeast-region neighborhoods (aOR 1.21; 95% CrI 1.03-1.42). There was significant clustering of incomplete HPV vaccination rates at the neighborhood level. Conclusions: This study revealed that individual- and neighborhood-level factors were associated with the risk of not completing the HPV vaccine series among individuals aged 27-45 years in the U.S. Interventions to improve HPV vaccination series completion rates for this age group should take into consideration both individual and contextual factors.

Determinants of Incomplete Vaccination Among Children Aged 12 to 23 Months in Gindhir District, Southeastern Ethiopia: Unmatched Case-Control Study

Background

Incomplete vaccination can put children at greater risk of acquiring vaccine-preventable diseases. In Ethiopia, vaccination coverage against vaccine-preventable diseases is still a significant and persistent public health challenge. Thus, the aim of this study was to identify the determinants of incomplete childhood vaccination among children aged 12-23 months in Gindhir District, Southeast Ethiopia.

Methods

A community-based unmatched case-control design was employed among children aged 12-23 months from 1 to 28 February 2020. A total of 254 cases and 508 controls were included using the stratified random sampling technique. Cases included children aged 12-23 months who missed at least one dose of the routine vaccination, and controls were the children with complete vaccination with all required doses. Binary logistic regression analyses were used to identify the independent factors for children's incomplete vaccination status.

Results

Of all assessed determinants, maternal knowledge about vaccination (AOR=0.50, 95% CI: 0.31, 0.80), educational status (AOR=2.61, 95% CI: 1.19, 5.67), average monthly income (AOR=0.33, 95% CI: 0.15, 0.77), model family (AOR = 2.50, 95% CI: 1.51, 4.14), taking TT vaccine (AOR= 0.45 95% CI: 0.29, 0.78), number of under five children (AOR= 4.90 95% CI: 1.72, 13.93) and birth order (AOR= 6.33, 95% CI: 1.89, 14.87) were found to have statistically significant association with childhood incomplete vaccination.

Conclusion

In this study, the mother's education, model family, birth order, average monthly income, and knowledge were some of the independent determinants of incomplete childhood vaccination. Improving maternal knowledge, income, and educational status should be the expectable measure to reduce incomplete vaccination.

Incomplete vaccination and associated factors among children aged 12-23 months in South Africa: an analysis of the South African demographic and health survey 2016

Background

Socioeconomic and health inequalities remain a huge problem in post-apartheid South Africa. Despite substantial efforts at ensuring universal access to vaccines, many children remain under-vaccinated in the country. This study aimed to assess the prevalence and factors associated with incomplete vaccination in the first year of life, among children aged 12–23 months in South Africa.

Methods

The study is a secondary analysis of the 2016 South African Demographic and Health Survey. A multivariable logistic regression model was applied to the data on 708 children aged 12–23 months. The study outcome, vaccination completeness, was assessed using a composite assessment of nine doses of four vaccines; Bacillus Calmette–Guérin (BCG) (one dose), Polio (four doses), diphtheria-tetanus-pertussis containing vaccines (DTP) (three doses) and measles-containing vaccines (MCV) (one dose). Children who received all the nine doses were categorized as completely vaccinated. Independent variables included child, maternal, and demographic characteristics. Variables were included in the model based on literature findings. Bivariate analyses were used to examine the crude association between each independent variable and incomplete vaccination, while the multivariable logistic regression model was used to examine the adjusted association after controlling for other variables. Measures of association were presented as odds ratios (OR) with their 95% confidence intervals (CI).

Results

About two-fifths (40.8%) of the children were incompletely vaccinated. The prevalence of incomplete vaccination was significantly high among children whose mothers did not receive antenatal care (ANC) during pregnancy (57.5%), and children living in Gauteng Province (52.2%). From the bivariate analyses, the odds of being incompletely vaccinated were three times higher in children whose mothers did not attend ANC compared with children whose mothers attended ANC (crude OR = 2.93; 95% CI 1.42–6.03). The odds were about three times higher in children living in Mpumalanga province (OR = 2.58; 95% CI 1.27–5.25) and in those living in Gauteng province (OR = 2.76; 95% CI 1.30–5.91), compared with those living in Free State province. Conversely, the odds were 32% lower in children from rich households, compared with those from poor households (OR = 0.68; 95% CI 0.47–0.98). In the adjusted model, the higher odds of incomplete vaccination in children whose mothers did not attend ANC were maintained in both magnitude and direction (adjusted OR [aOR] = 2.87; 95% CI 1.31–6.25). Similarly, compared with children living in Free State province, the higher odds of a child being incompletely vaccinated in Mpumalanga (aOR = 2.30; 95% CI 1.03–5.14) and in Gauteng (aOR = 3.10; 95% CI 1.35–7.15) provinces were maintained in both magnitude and direction.

Conclusions

There is a substantial burden of incomplete childhood vaccination in South Africa. Maternal ANC attendance during pregnancy and area of residence significantly influences this burden. Interventions that promote broader health service utilization, such as ANC attendance, can help improve the awareness and uptake of routine childhood vaccination. It is also imperative to take into consideration the provincial disparities in childhood vaccination completeness, in planning and implementing interventions to improve vaccination coverage in the country.