The impact of the COVID-19 pandemic on vaccination uptake in the United States and strategies to recover and improve vaccination rates: A review

The COVID-19 pandemic disrupted routine healthcare delivery, causing declines in CDC-recommended vaccination rates across the life-course in the United States (US). Ensuring protection against disease outbreaks and associated morbidity and mortality depends on improving vaccine coverage rates (VCRs) and uptake. The authors conducted a targeted literature review to assess the pandemic's effects on routine vaccination rates across different populations, evaluating VCR recovery and improvement efforts. The review highlights articles published with data measuring or evaluating VCR decline across the US during the COVID-19 pandemic from January 2020 to April 2022, associated health impacts, and policy and programmatic strategies to recover routine VCRs. While vaccination rates stagnated or declined across some populations pre-pandemic, the review indicated there were further VCR declines in 2020 and 2021 compared to 2019 across numerous CDC-recommended vaccines, ages, and geographies, with some vaccines and sub-populations disproportionally impacted. The review additionally identified declines in patient healthcare visit frequency and increases in morbidity and mortality associated with vaccine-preventable disease (VPD) complications. Reviewed publications highlighted multifaceted strategies that could aid in recovering VCRs. Overall, findings demonstrate a significant reduction in VCRs across all age groups and highlight promising solutions to inform vaccine uptake efforts and ensure broader protection against VPDs.

Impact of the COVID-19 pandemic on routine vaccination services in Shaanxi province, Northwest China: Non-pharmaceutical intervention period and mass COVID-19 vaccination period

To better understand the impact of COVID-19 epidemic on routine vaccination, a cross-sectional study was carried out during non-pharmaceutical intervention period (2020) and mass COVID-19 vaccination period (2021) in Shaanxi province. Data on NIP (National Immunization Program, Free), nNIP (non-National Immunization Program, Paid), and COVID-19 vaccines inoculated and vaccination clinics were collected. At the beginning of the COVID-19 epidemic, the rate of routine vaccination clinics providing vaccination services was only 20.0%, rabies vaccination clinics was 89.9% and obstetric vaccination clinics was 95.9%. Compared with 2019 (as baseline), NIP vaccines inoculated in 2020 and 2021 decreased by 3.5% and 19.2%, respectively, on the contrary, nNIP vaccines increased by 25.8% and 34.7%, respectively. In 2021, 74.9% of vaccination clinics were involved in mass COVID-19 vaccination, and there was not a significant impact of mass COVID-19 vaccination on the number of other vaccines inoculated. Vaccination coverage of all NIP vaccines was not different from that in previous years. COVID-19 epidemic had a short-term impact on routine vaccination at beginning. The impact of mass COVID-19 vaccination on routine vaccination could even be ignored. The COVID-19 epidemic has once again made people realize the great harm of infectious diseases, and has improved everyone's willingness to receive routine vaccines.

Factors Associated with Vaccine Refusal (Polio and Routine Immunization) in High-Risk Areas of Pakistan: A Matched Case-Control Study

BACKGROUND

Pakistan has subpar childhood immunization rates and immunization activities have faced several challenges over the past years. We evaluated the social-behavioral and cultural barriers and risk factors for refusal of polio, Routine Immunization (RI), or both in high-risk areas of poliovirus circulation.

METHODS

A matched case-control study was conducted from April to July 2017 in eight super high-risk Union Councils of five towns in Karachi, Pakistan. A total of 3 groups, each with 250 cases, including refusals for the Oral Polio Vaccine (OPV) in campaigns (national immunization days and supplementary immunization activities), RI, and both, were matched with 500 controls and identified using surveillance records. Sociodemographic characteristics, household information, and immunization history were assessed. Study outcomes included social-behavioral and cultural barriers and reasons for vaccine refusal. Data were analyzed in STATA using conditional logistic regression.

RESULTS

RI refusal was associated with illiteracy and fear of the vaccine's adverse effects, while OPV refusals were linked to the mother's decision authority and the assumption that the OPV caused infertility. Conversely, higher socioeconomic status (SES) and knowledge of and willingness to vaccinate with Inactivated Polio Vaccine (IPV) were inversely associated with RI; and lower SES, walking to the vaccination point, knowledge of IPV, and an understanding of contracting polio were inversely associated with OPV refusals, with the latter two also inversely associated with complete vaccine refusal.

CONCLUSION

Education, knowledge and understanding of vaccines, and socioeconomic determinants influenced OPV and RI refusals among children. Effective interventions are needed to address knowledge gaps and misconceptions among parents.

Acceptance of varicella vaccination

Varicella is a common vaccine-preventable disease that usually presents in children as a mild infection; however, severe complications also occur. The burden of varicella is significant in the terms of incidence, complication, and hospitalization rate related to varicella and economic disease burden. Despite the evidence of overall positive effects of varicella vaccination, there are great differences in the implementation of varicella vaccination and in the uptake of the vaccine from country to country. Improving acceptance of varicella vaccination on the national and on the individual level would decrease the burden of the disease on the health of children and on health-care resources. In studies determining factors of parental acceptance of varicella vaccination questions specific for varicella vaccination were highlighted. Addressing these issues with open, evidence based communication is important to improve and maintain the trust of the public in varicella vaccination.

Maternal influenza vaccination relates to receiving relevant information among pregnant women in Japan

Maternal vaccination for seasonal influenza is currently not listed as a routine vaccination in the national vaccination schedule of Japan. However, many pregnant women voluntarily receive an influenza vaccination. We explored the factors related to influenza vaccine uptake. We particularly focused on factors related to any recommendation, such as advice or suggestions from another individual. We conducted a cross-sectional web-based questionnaire survey in Japan among pregnant women or mothers who had recently given birth in March 2017 and 2018. Logistic regression models were used to determine the factors influencing vaccination uptake. Key individuals regarding maternal vaccination were examined using the network visualization software Gephi. The total number of valid responses was 2204 in 2017 and 3580 in 2018. Over 40% of respondents had been vaccinated with the seasonal influenza vaccine at some point in both years. Of the vaccinated respondents, over 80% received advice regarding the influenza vaccination. Obstetricians were the most common source of advice in both years. Among respondents who chose more than two sources, the largest link in the network of sources was found between the obstetrician and family members. Attention to public concern or potential recommenders, by public health authorities, not just pregnant women, about the benefits of maternal influenza vaccination is important.

Factors affecting age-appropriate timeliness of vaccination coverage among children in Lebanon

Background: The effect of immunization does not only depend on its completeness, but also on its timely administration. Routine childhood vaccinations schedules recommend that children receive the vaccine doses at specific ages. This article attempts to assess timeliness of routine vaccination coverage among a sub-sample of children from a survey conducted in 2016. Methods: This analysis was based on data from a cross-sectional multistage cluster survey conducted between December 2015 and June 2016 among caregivers of children aged 12-59 months in all of Lebanon using a structured survey questionnaire. The analysis used Kaplan-Meier curves and logistic regression to identify the predictors of age-appropriate immunization. Results: Among the 493 randomly selected children, timely administration of the third dose of polio vaccine, diphtheria-tetanus-pertussis (DTP)-containing vaccine and hepatitis B (HepB) vaccine occurred in about one-quarter of children. About two-thirds of children received the second dose of a measles-containing vaccine (MCV) within the age interval recommended by the Expanded Programme on Immunization (EPI). Several factors including socio-demographic, knowledge, beliefs and practices were found to be associated with age-appropriate vaccination; however, this association differed between the types and doses of vaccine. Important factors associated with timely vaccination included being Lebanese as opposed to Syrian and being born in a hospital for hepatitis B birth dose; believing that vaccination status was up-to-date was related to untimely vaccination. Conclusions: The results suggest that there is reason for concern over the timeliness of vaccination in Lebanon. Special efforts need to be directed towards the inclusion of timeliness of vaccination as another indicator of the performance of the EPI in Lebanon.

Routine vaccination coverage of children aged 1-7 years in Zhejiang province, China

BACKGROUND

This study was to evaluate the coverage, completeness and timeliness of routine vaccination among children aged 1-7 years in Zhejiang province.

METHODS

Demographic information and immunization records of 4613160 children born from Jan 1, 2010 to Dec 31, 2016 were extracted from Zhejiang provincial immunization information system (ZJIIS) on Dec 31, 2017. Vaccination coverage for each vaccine dose and completeness of different vaccine series were calculated by birth cohort, immigration status, and geographic area. The timeliness of vaccine doses scheduled before 12 months of age for the 2016 birth cohort was also examined Results: Coverage of all the vaccine doses scheduled before 12 months of age and its completeness reached the target goal of 90%. The coverage and completeness decreased substantially in vaccinations scheduled after 12 months old, and most of them were below 90%. The coverage and timeliness estimates of migrant children was lower than those of resident children and the coverage of WenZhou (WZ), Zhoushan (ZS) and Lishui (LS) was lower than other cities across all the birth cohorts. Despite high coverage rates for all antigens by age 12 months, there was a very large range of percent of vaccination delay when comparing different antigens scheduled in the first year of life for the 2016 birth cohort.

CONCLUSIONS

This study demonstrated the success and improvement of immunization program in Zhejiang province, and identified some challenges. Strategies such as assessment, feedback, incentives, and exchange program, reminder/recall activity, home visits, immunization requirement for school's enrollment could be used to reach a higher coverage of the population.

Estimated impact of rotavirus vaccine on hospitalizations and deaths from rotavirus diarrhea among children <5 in Asia

BACKGROUND

Of the 215,000 global deaths from rotavirus estimated in 2013, 41% occur in Asian countries. However, despite a recommendation for global rotavirus vaccination since 2009, only eight countries in Asia have introduced the rotavirus vaccine into their national immunization program as of September 2017. To help policy makers assess the potential value of vaccination, we projected the reduction in rotavirus hospitalizations and deaths following a hypothetical national introduction of rotavirus vaccines in all countries in Asia using data on national-level rotavirus mortality, <5 population, rotavirus hospitalizations rates, routine vaccination coverage, and vaccine effectiveness.

METHODS

To quantify uncertainty, we generated 1,000 simulations of these inputs.

RESULTS

Our model predicted 710,000 fewer rotavirus hospitalizations, a 49% decrease from the 1,452,000 baseline hospitalizations and 35,000 fewer rotavirus deaths, a 40% decrease from the 88,000 baseline deaths if all 43 Asian countries had introduced rotavirus vaccine. Similar reductions were projected in subanalyses by vaccine introduction status, subregion, and birth cohort size.

CONCLUSION

Rotavirus vaccines will substantially reduce morbidity and mortality due to rotavirus infections in Asia.

Maternal pertussis immunisation: clinical gains and epidemiological legacy

The increase in whooping cough (pertussis) incidence in many countries with high routine vaccination coverage is alarming, with incidence in the US reaching almost 50,000 reported cases per year, reflecting incidence levels not seen since the 1950s. While the potential explanations for this resurgence remain debated, we face an urgent need to protect newborns, especially during the time window between birth and the first routine vaccination dose. Maternal immunisation has been proposed as an effective strategy for protecting neonates, who are at higher risk of severe pertussis disease and mortality. However, if maternally derived antibodies adversely affect the immunogenicity of the routine schedule, through blunting effects, we may observe a gradual degradation of herd immunity. 'Wasted' vaccines would result in an accumulation of susceptible children in the population, specifically leading to an overall increase in incidence in older age groups. In this Perspective, we discuss potential long-term epidemiological effects of maternal immunisation, as determined by possible immune interference outcomes.

Individually Linked Household and Health Facility Vaccination Survey in 12 At-risk Districts in Kinshasa Province, Democratic Republic of Congo: Methods and Metadata

Health facility (HF) and household (HH) data can complement each other to provide a better understanding of the factors that contribute to vaccination status. In 12 zones with low vaccination coverage within Kinshasa Province, Democratic Republic of Congo, we conducted 2 surveys: (1) a linked HH and HF survey among 6-11-month-old infants, and (2) a HH survey among 12-23-month-old children. Linked survey objectives were to identify factors associated with vaccination status and to explore methodological considerations for linked survey implementation. To provide linked HH and HF data, we enrolled 6-11-month-old infants in HH clusters in each zone and then surveyed HFs located within the 12 zones and cited by caregivers of the enrolled infants as the most recent HF visited for vaccination or curative care. To provide vaccination coverage estimates for the 12-zone area, we enrolled 12-23-month-old children in every fourth HH. Of the HHs with a child aged 6-23 months, 16% were ineligible because they had resided in the neighborhood for <3 months or were unavailable to be interviewed, 4% refused, and 80% were eligible and participated. Of 1224 enrolled infants 6-11 months of age, records of 879 (72%) were linked to one of the 182 surveyed HFs. For the coverage survey, 710 children aged 12-23 months participated. Home-based vaccination cards were available for 1210 of 1934 children (63%) surveyed. The surveys were successful in assessing HH information for 2 age groups, documenting written vaccination history for a large proportion of 6-23-month-old children, linking the majority of infants with their most recently visited HF, and surveying identified HFs. The implementation of the individually linked survey also highlighted the need for a comprehensive list of HFs and an analysis plan that addresses cross-classified clusters with only 1 child.

Vaccination coverage and factors influencing routine vaccination status in 12 high risk health zones in the Province of Kinshasa City, Democratic Republic of Congo (DRC), 2015

Introduction

Vaccination coverage of the first dose of diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenza type b (pentavalent) vaccine for the City-Province of Kinshasain the years 2012 – 2014 wasbelow the national objective of 92%, with coverage less than 80% reported in 12 of the 35 health zones (HZ). The purpose of this study was to discern potential contributing factors to low vaccination coverage in Kinshasa.

Methods

We conducted a multi-stage cluster household study of children 6 – 11 months in households residing in their current neighborhood for at least 3 months in the 12 high risk HZ in Kinshasa. Additional information on vaccination status of the children was collected at the health facility.

Results

Of the 1,513 households with a child 6-11 months old, 81% were eligible and participated. Among the 1224 children surveyed, 96% had received the first dose of pentavalent vaccine; 84% had received the third dose; and 71% had received all recommended vaccines for their age. Longer travel time to get to health facility (p=0.04) and shorter length of residence in the neighborhood (p=0.04) showed significant differences in relation to incomplete vaccination. Forty percent of children received their most recent vaccination in a facility outside of their HZ of residence.

Conclusion

This survey found vaccination coverage in 12 HZs in Kinshasa was higher than estimates derived from administrative reports. The large percentage of children vaccinated outside of their HZ of residence demonstrates the challenge to use of the Reaching Every District strategy in urban areas.

Forecasting Epidemiological Consequences of Maternal Immunization

BACKGROUND

 The increase in the incidence of whooping cough (pertussis) in many countries with high vaccination coverage is alarming. Maternal pertussis immunization has been proposed as an effective means of protecting newborns during the interval between birth and the first routine dose. However, there are concerns regarding potential interference between maternal antibodies and the immune response elicited by the routine schedule, with possible long-term population-level effects.

METHODS

 We formulated a transmission model comprising both primary routine and maternal immunization. This model was examined to evaluate the long-term epidemiological effects of routine and maternal immunization, together with consequences of potential immune interference scenarios.

RESULTS

 Overall, our model demonstrates that maternal immunization is an effective strategy in reducing the incidence of pertussis in neonates prior to the onset of the primary schedule. However, if maternal antibodies lead to blunting, incidence increases among older age groups. For instance, our model predicts that with 60% routine and maternal immunization coverage and 30% blunting, the incidence among neonates (0-2 months) is reduced by 43%. Under the same scenario, we observe a 20% increase in incidence among children aged 5-10 years. However, the downstream increase in the older age groups occurs with a delay of approximately a decade or more.

CONCLUSIONS

 Maternal immunization has clear positive effects on infant burden of disease, lowering mean infant incidence. However, if maternally derived antibodies adversely affect the immunogenicity of the routine schedule, we predict eventual population-level repercussions that may lead to an overall increase in incidence in older age groups.

Economic evaluation of routine infant rotavirus immunisation program in Japan

Two rotavirus vaccines are currently available in Japan. We estimated the incremental cost-effectiveness ratio (ICER) of routine infant rotavirus immunisation program without defining which vaccine to be evaluated, which reflects the current deliberation at the Health Science Council in charge of Immunisation and Vaccine established by the Ministry of Health, Labor and Welfare of Japan. Three ICERs were estimated, one from payers' perspective and 2 from societal perspective depending on the scenarios to uptake vaccines. The health statuses following the birth cohort were as follows: not infected by rotavirus, asymptomatic infection, outpatients after infection, hospitalised after infection, developing encephalitis/encephalopathy followed by recovery, sequelae, and death. Costs of per course of vaccination was ¥30,000 (US$283; US$1 = ¥106). The model runs for 60 months with one month cycle. From payers' perspective, estimated ICERs were ¥6,877,000 (US$64,877) per QALY. From societal perspective, immunisation program turns out to be cost-saving for 75% simultaneous vaccination scenario, while it is at ¥337,000 (US$3,179) per QALY gained with vaccine alone scenario. The probability of rotavirus immunisation program to be under ¥5,000,000 (US$47,170) per QALY was at 19.8%, 40.7%, and 75.6% when costs per course of vaccination were set at ¥30,000 (US$283), ¥25,000 (US$236), and ¥20,000 (US$189), respectively. Rotavirus immunisation program has a potential to be cost-effective from payers' perspective and even cost-saving from societal perspective in Japan, however, caution should be taken with regard to the interpretation of the results as cost-effectiveness is critically dependent on vaccination costs.

Factors Associated with Parental Refusal of Routine Vaccination in the Czech Republic

AIM

Routine vaccination is one of the most important preventive methods which is responsible for the decreasing trend of morbidity and mortality of vaccine preventable infectious diseases, their complications and sequelae. The impact of vaccination on declining trend of these diseases is well known and confirmed by a large number of epidemiological studies. In the Czech Republic, there is high vaccination coverage in regards to most vaccine preventable diseases. However, during the last decade proportion of parents refusing routine vaccination of their children due to different factors is increasing. The presented study evaluates current situation in the Czech Republic and describes the most significant factors in parents decision making.

METHODS

The study was conducted between 1 July 2013 and 31 March 2014 as a questionnaire based survey (cross-sectional study). The questionnaire was created with multiple choice answers. Questions were addressed to parents or legal representatives of children aged 0-18 years. Types of questions were divided into several subgroups. The study was performed in the Czech Republic in two different districts of Prague and Zlín.

RESULTS

In the sample size (n=480) we detected 11 parents who refused vaccination of 11 children (2.29%). The most often refused vaccines in the prevalence study were hexavaccine (1st dose) and measles, mumps and rubella vaccine (1st dose). The hexavaccine includes tetanic anatoxin, diphtheric anatoxin, acellular pertussis vaccine, conjugate vaccine against Haemophilus influenzae b, inactivated polio vaccine, and recombinant vaccine against viral hepatitis B. The measles, mumps, rubella vaccine contains live attenuated viruses of measles, mumps, rubella.

CONCLUSION

We observed increasing trend of routine vaccination refusal in children during the last ten years (compared to situation in the year 2004, p<0.001). The most important factors associated with this progression were distrust to vaccination, fear of some vaccine components and fear of adverse reactions.

Understanding interventions for improving routine immunization coverage in children in low- and middle-income countries: a systematic review protocol

BACKGROUND

Virtually all low- and middle-income countries are dependent on the World Health Organization's Expanded Program on Immunization for delivery of vaccines to children. The Expanded Program on Immunization delivers routine immunization services from health facilities free of charge. Understanding interventions for improving immunization coverage remains key in achieving universal childhood immunization.

METHODS

We will conduct a systematic review that aims to assess the effectiveness of the full range of potential interventions to improve routine immunization coverage in children in low- and middle-income countries. We will include intervention studies, as well as observational studies. We will search the Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, electronic databases for eligible studies published by 31 August 2013. At least two authors will independently screen search outputs, select studies, extract data and assess the risk of bias (using separate criteria for interventions and observational studies); resolving any disagreements by discussion and consensus. The use of logic models and the Cochrane Complexity Matrix will be explored in order to better understand and contextualize studies. We will express the result of each study as a risk ratio with its corresponding 95% confidence intervals for dichotomous data, or mean difference with its standard deviation for continuous data. We will conduct meta-analysis for the same type of participants, interventions, study designs, and outcome measures where homogeneity of data allows. Use of harvest plots may be explored as an alternative. Heterogeneity will be assessed using the χ² test of heterogeneity, and quantified using the I2 statistic. This protocol has not been registered with PROSPERO.

DISCUSSION

This review will allow us to document evidence across a broad range of intervention types for improving routine immunization coverage in children and also distinguish between those that are well supported by evidence (to direct policy recommendations) and those that are not well supported (to direct research agenda).