Impact of the COVID-19 pandemic on routine childhood vaccination in 9 U.S. jurisdictions.

IMPORTANCE: Routine vaccinations are key to prevent outbreaks of vaccine-preventable diseases. However, there have been documented declines in routine childhood vaccinations in the U.S. and worldwide during the COVID-19 pandemic. OBJECTIVE: Assess how the COVID-19 pandemic impacted routine childhood vaccinations by evaluating vaccination coverage for routine childhood vaccinations for children born in 2016-2021. METHODS: Data on routine childhood vaccinations reported to CDC by nine U.S. jurisdictions via the immunization information systems (IISs) by December 31, 2022, were available for analyses. Population size for each age group was obtained from the National Center for Health Statistics' Bridging Population Estimates. MAIN OUTCOMES AND MEASURES: Vaccination coverage for routine childhood vaccinations at age three months, five months, seven months, one year, and two years was calculated by vaccine type and overall, for 4:3:1:3:3:1:4 series (≥4 doses DTaP, ≥3 doses Polio, ≥1 dose MMR, ≥3 doses Hib, ≥3 doses Hepatitis B, ≥1 dose Varicella, and ≥ 4 doses pneumococcal conjugate), for each birth cohort year and by jurisdiction. RESULTS: Overall, there was a 10.4 percentage point decrease in the 4:3:1:3:3:1:4 series in those children born in 2020 compared to those children born in 2016. As of December 31, 2022, 71.0% and 71.3% of children born in 2016 and 2017, respectively, were up to date on their routine childhood vaccinations by two years of age compared to 69.1%, 64.7% and 60.6% for children born in 2018, 2019, and 2020, respectively. CONCLUSIONS AND RELEVANCE: The decline in vaccination coverage for routine childhood vaccines is concerning. In order to protect population health, strategic efforts are needed by health care providers, schools, parents, as well as state, local, and federal governments to work together to address these declines in vaccination coverage during the COVID-19 pandemic to prevent outbreaks of vaccine preventable diseases by maintaining high levels of population immunity.

Association of Group B Meningococcal Vaccine Receipt With Reduced Gonorrhea Incidence Among University Students.

This case-control study examines reported cases of gonorrhea among recipients of meningococcal group B vaccine at 2 universities in Oregon.

Clinic-level differences in human papillomavirus vaccination rates among rural and urban Oregon primary care clinics.

PURPOSE: Human papillomavirus (HPV) infection contributes to vaccine-preventable malignancies. Rural populations experience lower HPV vaccination rates despite similar rates of other childhood vaccinations. Individual- and clinic-level characteristics likely contribute to this disparity, but little is known about the separate roles of each. We compared clinic-level HPV vaccination rates among rural versus urban primary care clinics, identified factors associated with HPV vaccination, and separately assessed the impact of individual- and clinic-level characteristics on rural disparities in HPV vaccination. METHODS: This cross-sectional study included 537 Oregon primary care clinics participating in the Vaccines for Children (VFC) program during 2019. Vaccination status was assessed using Oregon's ALERT Immunization Information System and included HPV vaccine ≥ 1 dose for ages 11 and 12; HPV vaccination up to date (UTD) for ages 13-17, and coadministration with tetanus, diphtheria, and acellular pertussis (Tdap). Rural versus urban clinic-level outcomes were assessed using negative binomial regression. FINDINGS: Participating clinics were 24.5% rural and 75.6% urban. Family medicine clinics comprised 71.1%; pediatrics, 16.9%; and mixed, 12.1%. Across clinics, the average proportion of patients qualifying for VFC was 43%, and non-White patients were 14.1%. The mean rate of HPV vaccine ≥1 dose was lower among rural clinics (46.9% vs 51.1%, P = .039), as was vaccination UTD (40.5% vs 49.9%, P < .001). Adjusting for differences in individual- and clinic-level characteristics, rural disparities were no longer statistically significant. CONCLUSIONS: Both individual- and clinic-level characteristics play a role in rural disparities in HPV vaccination, and modifiable clinic-level differences may be opportune targets to address these disparities.

Influenza Vaccinations During the COVID-19 Pandemic - 11 U.S. Jurisdictions, September-December 2020.

Influenza causes considerable morbidity and mortality in the United States. Between 2010 and 2020, an estimated 9-41 million cases resulted in 140,000-710,000 hospitalizations and 12,000-52,000 deaths annually (1). As the United States enters the 2021-22 influenza season, the potential impact of influenza illnesses is of concern given that influenza season will again coincide with the ongoing COVID-19 pandemic, which could further strain overburdened health care systems. The Advisory Committee on Immunization Practices (ACIP) recommends routine annual influenza vaccination for the 2021-22 influenza season for all persons aged ≥6 months who have no contraindications (2). To assess the potential impact of the COVID-19 pandemic on influenza vaccination coverage, the percentage change between administration of at least 1 dose of influenza vaccine during September-December 2020 was compared with the average administered in the corresponding periods in 2018 and 2019. The data analyzed were reported from 11 U.S. jurisdictions with high-performing state immunization information systems.* Overall, influenza vaccine administration was 9.0% higher in 2020 compared with the average in 2018 and 2019, combined. However, in 2020, the number of influenza vaccine doses administered to children aged 6-23 months and children aged 2-4 years, was 13.9% and 11.9% lower, respectively than the average for each age group in 2018 and 2019. Strategic efforts are needed to ensure high influenza vaccination coverage among all age groups, especially children aged 6 months-4 years who are not yet eligible to receive a COVID-19 vaccine. Administration of influenza vaccine and a COVID-19 vaccine among eligible populations is especially important to reduce the potential strain that influenza and COVID-19 cases could place on health care systems already overburdened by COVID-19.

Impact of the COVID-19 Pandemic on Administration of Selected Routine Childhood and Adolescent Vaccinations - 10 U.S. Jurisdictions, March-September 2020.

After the March 2020 declaration of the COVID-19 pandemic in the United States, an analysis of provider ordering data from the federally funded Vaccines for Children program found a substantial decrease in routine pediatric vaccine ordering (1), and data from New York City and Michigan indicated sharp declines in routine childhood vaccine administration in these areas (2,3). In November 2020, CDC interim guidance stated that routine vaccination of children and adolescents should remain an essential preventive service during the COVID-19 pandemic (4,5). To further understand the impact of the pandemic on routine childhood and adolescent vaccination, vaccine administration data during March-September 2020 from 10 U.S. jurisdictions with high-performing* immunization information systems were assessed. Fewer administered doses of routine childhood and adolescent vaccines were recorded in all 10 jurisdictions during March-September 2020 compared with those recorded during the same period in 2018 and 2019. The number of vaccine doses administered substantially declined during March-May 2020, when many jurisdictions enacted stay-at-home orders. After many jurisdictions lifted these orders, the number of vaccine doses administered during June-September 2020 approached prepandemic baseline levels, but did not increase to the level that would have been necessary to catch up children who did not receive routine vaccinations on time. This lag in catch-up vaccination might pose a serious public health threat that would result in vaccine-preventable disease outbreaks, especially in schools that have reopened for in-person learning. During the past few decades, the United States has achieved a substantial reduction in the prevalence of vaccine-preventable diseases driven in large part to the ongoing administration of routinely recommended pediatric vaccines. These efforts need to continue even during the COVID-19 pandemic to reduce the morbidity and mortality from vaccine-preventable diseases. Health care providers should assess the vaccination status of all pediatric patients, including adolescents, and contact those who are behind schedule to ensure that all children are fully vaccinated.

The Impact of the Number of Injections per Visit on the Likelihood of Human Papillomavirus Immunization.

Objective: To test whether adolescents, who are injection limited, that is, receiving only a limited number of immunization injections per visit, are less likely to complete the human papillomavirus (HPV) immunization series. Study design: For Oregon adolescents age 13-17 years, HPV series completion rates were assessed based on never receiving >1 injection per visit from age ≥9 years. Among a study subset born and resident in Oregon through adolescence, HPV series rates were assessed based on never receiving >1 or 2 injections per visit from age ≥4 years. Cox proportional hazards regression was used to assess delays owing to limiting injections, controlling for sex and rural location. Results: Among 241 453 study adolescents, 16.3% had only single-injection visits from age ≥9 years. Their HPV completion rate was 7.7% as compared with 61.7% for those with no limitations of number of injections. Among study adolescents born in Oregon, 10.2% never received >1 or 2 injections per visit from age ≥4 and were less than half as likely to complete the HPV series (28.4% vs 59.1%). Conclusions: Limiting the number of injections per visit is associated with decreased completion of HPV immunization. As larger cohorts of young children with early injection-limiting characteristics age into adolescence, progress on HPV immunization rates may be challenged.

Assessing the effectiveness of high-dose influenza vaccine in preventing hospitalization among seniors, and observations on the limitations of effectiveness study design.

BACKGROUND: The availability of high-dose (HD) influenza vaccine for seniors should decrease influenza-related hospitalization. Studies to date show a range of mostly moderate increased HD vaccine effectiveness (VE). While a 'healthy vaccinee' phenomenon can inflate VE, for influenza and particularly an HD vaccine targeted at frailer adults, an 'at-risk vaccinee' bias may deflate VE estimates. We assessed senior HD vaccine effectiveness against influenza-related hospitalization by linking immunization registry records to hospitalizations. We also examined whether adding strata typically ignored in case-control matching schemas, such as residence areas, exact age, and provider biases, would increase VE. METHODS: For the 2016-17 influenza season in the Portland metropolitan area, the differential VE for the HD vaccine in preventing PCR-confirmed influenza hospitalization was assessed by a nested series of models across matching strata. For an exact match for high-dose and standard-dose seniors, matching elements included exact age, gender, residence type, race-ethnicity, provider bias, and residence area (zipcode). RESULTS: As a first step, a simple aggregate comparison of influenza-related hospitalization risk showed no added HD effectiveness. For the nested models, adding strata increased VE. In the final model, among 23,712 matched pairs of HD to SD vaccinated seniors, the HD vaccine was 30.7% (95%CI: 8-48%) more effective in preventing influenza-related hospitalization. CONCLUSION: For this study, the high-dose influenza vaccine provided superior protection for seniors against influenza hospitalization. Including matching elements as exact year of age and residence zipcode all added to the calculation of VE. As a warning, non-matched or overly simple matched VE study designs may substantially under-estimate VE.

Changes in Influenza Vaccination Rates After Withdrawal of Live Vaccine.

BACKGROUND: Before the start of the 2016-2017 influenza season, the Advisory Committee on Immunization Practices withdrew its recommendation promoting the use of live attenuated influenza vaccines (LAIVs). There was concern that this might lessen the likelihood that those with a previous LAIV would return for an injectable influenza vaccine (IIV) and that child influenza immunization rates would decrease overall. METHODS: Using Oregon's statewide immunization registry, the ALERT Immunization Information System, child influenza immunization rates were compared across the 2012-2013 through 2016-2017 seasons. Additionally, matched cohorts of children were selected based on receipt of either an LAIV or an IIV during the 2015-2016 season. Differences between the IIV and LAIV cohorts in returning for the IIV in the 2016-2017 season were assessed. RESULTS: Overall, influenza immunization rates for children aged 2 to 17 years were unchanged between the 2015-2016 and 2016-2017 seasons. Children aged 3 to 10 with a previous IIV were 1.03 (95% confidence interval, 1.02 to 1.04) times more likely to return for an IIV in 2016-2017 than those with a previous LAIV, whereas children aged 11 to 17 years with a previous IIV were 1.08 (95% confidence interval, 1.05 to -1.09) times more likely to return. CONCLUSIONS: Withdrawal of the LAIV recommendation was not associated with an overall change in child influenza immunization rates across seasons. Children with a previous (2015-2016) IIV were slightly more likely to return during the 2016-2017 season for influenza immunization than those with a previous LAIV.

The Concordance of Parent and Child Immunization.

BACKGROUND: A substantial body of work has related survey-based parental vaccine hesitancy to noncompliant childhood immunization. However little attention has been paid to the connection between parents' own immunization behavior and the immunizations their children receive. METHODS: Using the Oregon ALERT Immunization Information System, we identified adult caregiver-child pairs for children between 9 months and 17 years of age. The likelihood of adult-child concordance of influenza immunization per influenza season from 2010-2011 through 2014-2015 was assessed. The utility of adult immunization as a predictor was also assessed for other, noninfluenza recommended immunizations for children and adolescents. RESULTS: A total of 450 687 matched adult caregiver-child pairs were included in the study. The children of immunizing adults were 2.77 times more likely to also be immunized for seasonal influenza across all seasons (95% confidence interval, 2.74-2.79), with similar results applying within each season. Adult immunization status was also significantly associated with the likelihood of children and adolescents getting other noninfluenza immunizations, such as the human papillomavirus vaccine (HPV). When adults improved their own behavior from nonimmunizing to immunizing across influenza seasons, their children if not immunized in the previous season were 5.44 times (95% confidence interval, 5.35-5.53) more likely to become immunized for influenza. CONCLUSIONS: Children's likelihood of following immunization recommendations is associated with the immunization behavior of their parents. Encouraging parental immunization is a potential tool for increasing children's immunization rates.

Do Pertussis Vaccines Protect Against Bordetella parapertussis?

We calculated the effectiveness of pertussis vaccine in preventing parapertussis among Oregon children 2 months to 10 years of age using 2 methods. During 2011-2016, the 2 VE methods found 66% (95% CI, 59-75%) and 82% (95% CI, 69-90%) effectiveness against parapertussis. Pertussis vaccine may induce cross-immunity.

The Timing of Pertussis Cases in Unvaccinated Children in an Outbreak Year: Oregon 2012.

OBJECTIVE: To assess whether, during a 2012 pertussis outbreak, unvaccinated and poorly vaccinated cases occurred earlier on a community level. STUDY DESIGN: Pediatric pertussis among children 2 months to 10 years of age in the Oregon Sentinel Surveillance region during an epidemic starting at the beginning of 2012 were stratified by immunization status, age, zip code, and calendar date of disease onset. Differences in median onset as days between fully or mostly vaccinated, poorly vaccinated, and unvaccinated cases were examined overall and within local zip code areas. Disease clusters also were examined using SatScan analysis. RESULTS: Overall, 351 pertussis cases occurred among children aged 2 months to 10 years of age residing in 72 distinct zipcodes. Among unvaccinated or poorly vaccinated cases, their median date of onset was at calendar day 117 (April 26, 2012), whereas for those who were fully or mostly vaccinated the median date of onset was 41 days later, at day 158 (June 6, 2012). Within each local zip code area, the unvaccinated cases were 3.2 times more likely than vaccinated cases to have earlier median dates of onset (95% CI 2.9-3.6). CONCLUSION: In this outbreak, pertussis cases among unvaccinated children represented an earlier spread of disease across local areas. Controlling outbreaks may require attention to the composition and location of the unvaccinated.

Impact of pharmacists providing immunizations on adolescent influenza immunization.

OBJECTIVES: To determine if the Oregon law change in 2011 to allow pharmacists to immunize adolescents 11 to 17 years of age increased influenza immunizations or changed existing immunization venues. METHODS: With the use of Oregon's ALERT Immunization Information System (IIS), 2 measures of impact were developed. First, the change in adolescent age 11-17 influenza immunizations before (2007-2010) and after (2011-2014) the pharmacy law change was evaluated against a reference cohort (aged 7-10) not affected by the law. Community pharmacies were also compared with other types of influenza immunization sites within one of the study influenza seasons (2013-2014). RESULTS: From 2007 to 2014, adolescent influenza immunizations at community pharmacies increased from 36 to 6372 per year. After the 2011 pharmacy law change, adolescents aged 11 to 17 were more likely to receive an influenza immunization compared with the reference population (odds ratio, 1.21; 95% CI, 1.19-1.22). Analysis of the 2013-2014 influenza season suggests that community pharmacies immunized a different population of adolescents than other providers. CONCLUSION: The 2011 change in Oregon law allowed pharmacists to increase the total of influenza immunizations given to adolescents.

Addressing immunization registry population inflation in adolescent immunization rates.

OBJECTIVE: While U.S. adolescent immunization rates are available annually at national and state levels, finding pockets of need may require county or sub-county information. Immunization information systems (IISs) are one tool for assessing local immunization rates. However, the presence of IIS records dating back to early childhood and challenges in capturing mobility out of IIS areas typically leads to denominator inflation. We examined the feasibility of weighting adolescent immunization records by length of time since last report to produce more accurate county adolescent counts and immunization rates. METHODS: We compared weighted and unweighted adolescent denominators from the Oregon ALERT IIS, along with county-level Census Bureau estimates, with school enrollment counts from Oregon's annual review of seventh-grade school immunization compliance for public and private schools. Adolescent immunization rates calculated using weighted data, for the state as a whole, were also checked against comparable National Immunization Survey (NIS) rates. RESULTS: Weighting individual records by the length of time since last activity substantially improved the fit of IIS data to county populations for adolescents. A nonlinear logarithmic (ogive) weight produced the best fit to the school count data of all examined estimates. Overall, the ogive weighted results matched NIS adolescent rates for Oregon. CONCLUSION: The problem of mobility-inflated counts of teenagers can be addressed by weighting individual records based on time since last immunization. Well-populated IISs can rely on their own data to produce adolescent immunization rates and find pockets of need.

Pertussis vaccine performance in an epidemic year-Oregon, 2012.

A 2012 pertussis epidemic in Oregon afforded an opportunity to measure vaccine effectiveness; it ranged from 95% (95% confidence interval [CI], 92%-97%) among children 15-47 months of age to 47% (95% CI, 19%-65%) among adolescents 13-16 years of age. In all age groups, pertussis incidence was higher among unimmunized persons.

Sick-visit immunizations and delayed well-baby visits.

OBJECTIVE: Giving recommended immunizations during sick visits for minor and acute illness such as acute otitis media has long been an American Academy of Pediatrics/Advisory Committee on Immunization Practice recommendation. An addition to the American Academy of Pediatrics policy in 2010 advised considering whether giving immunizations at the sick visit would discourage making up missed well-baby visits. This study quantifies the potential tradeoff between sick-visit immunizations and well-baby visits. METHODS: This study was a retrospective cohort analysis with a case-control component of sick visits for acute otitis media that supplanted normal well-baby visits at age 2, 4, or 6 months. Infants were stratified for sick-visit immunization, no sick-visit immunization but quick makeup well-baby visits, or no sick-visit immunizations or quick makeup visits. Immunization rates and well-baby visit rates were assessed through 24 months of age. RESULTS: For 1060 study cases, no significant difference was detected in immunization rates or well-baby visits through 24 months of age between those with or without sick-visit immunizations. Thirty-nine percent of infants without a sick-visit shot failed to return for a quick makeup well-baby visit; this delayed group was significantly less likely to be up-to-date for immunizations (relative risk: 0.66) and had fewer well-baby visits (mean: 3.8) from 2 through 24 months of age compared with those with sick-visit shots (mean: 4.7). CONCLUSIONS: The substantial risk that infants will not return for a timely makeup well-baby visit after a sick visit should be included in any consideration of whether to delay immunizations.

Incomplete Early Childhood Immunization Series and Missing Fourth DTaP Immunizations; Missed Opportunities or Missed Visits?

The successful completion of early childhood immunizations is a proxy for overall quality of early care. Immunization statuses are usually assessed by up-to-date (UTD) rates covering combined series of different immunizations. However, series UTD rates often only bear on which single immunization is missing, rather than the success of all immunizations. In the US, most series UTD rates are limited by missing fourth DTaP-containing immunizations (diphtheria/tetanus/pertussis) due at 15 to 18 months of age. Missing 4th DTaP immunizations are associated either with a lack of visits at 15 to 18 months of age, or to visits without immunizations. Typical immunization data however cannot distinguish between these two reasons. This study compared immunization records from the Oregon ALERT IIS with medical encounter records for two-year olds in the Oregon Health Plan. Among those with 3 valid DTaPs by 9 months of age, 31.6% failed to receive a timely 4th DTaP; of those without a 4th DTaP, 42.1% did not have any provider visits from 15 through 18 months of age, while 57.9% had at least one provider visit. Those with a 4th DTaP averaged 2.45 encounters, while those with encounters but without 4th DTaPs averaged 2.23 encounters.