Why Parents Say No to Having Their Children Vaccinated against Measles: A Systematic Review of the Social Determinants of Parental Perceptions on MMR Vaccine Hesitancy

Addressing Vaccine Hesitancy: Validating the PACV Survey for Croatian Parents

Background/Objectives: Vaccine hesitancy, recognized by the WHO as a significant global health threat, undermines vaccination efforts. This study aimed to adapt and validate the Parent Attitudes about Childhood Vaccines (PACV) Survey for Croatian parents to understand vaccine hesitancy better. Methods: A cross-sectional study with 1814 Croatian parents was conducted using the PACV survey, translated using a double-back translation method. The psychometrics of the questionnaire were examined, including content validity, dimensionality, construct validity, discriminant validity, and reliability. Confirmatory factor analysis (CFA) assessed the original model's validity, but the original model fit poorly, prompting exploratory factor analysis (EFA) to identify latent factors. Reliability was measured using Cronbach's alpha and McDonald's omega. Results: EFA identified a five-factor model with factors labeled "Safety", "Schedule", "Attitudes", "Behavior", and "Trust". Subsequent CFA confirmed this model with acceptable to good fit indices. Discriminant validity was also confirmed. Reliability analyses indicated high internal consistency, with total Cronbach's alpha at 0.926 and McDonald's omega at 0.931. Conclusions: The adapted PACV is a valid and reliable tool for identifying vaccine hesitancy among Croatian parents. This study revealed high vaccine hesitancy among Croatian parents, emphasizing the need for targeted interventions.

Peer education as a strategy to promote vaccine acceptance: A randomized controlled trial within New York community healthcare practices

BACKGROUND

Effective strategies are needed to improve vaccine acceptance. This study sought to determine if a peer-led vaccine education intervention embedded within community medical practices increases parental acceptance of pediatric pneumococcal conjugate vaccination.

METHODS

From March 2022-July 2023, we conducted a randomized trial at three pediatric health practices in predominantly Hasidic Jewish neighborhoods in New York, where vaccine deferral is common. Parents of children up to 18 months due/overdue for routine pneumococcal vaccination were randomized (1:1) to receive routine care alone or routine care plus a peer educational intervention. Peer educators trained in motivational interviewing and vaccine science provided counseling at enrollment and follow-up telephone engagement in the intervention arm at day 30 and 60. Primary outcome was child's pneumococcal immunization status by allocation arm expressed as at least one dose received between enrollment and 90 days post-enrollment.

RESULTS

144 parent-child dyads were eligible for outcome analysis. Participants in the group receiving routine care along with peer-led vaccine counseling were significantly more likely to have their child receive at least 1 vaccine dose between enrollment and 90 days compared to the group who received routine care alone (28.4 % vs 12.9 %, risk ratio [RR] 2.21, confidence interval [CI] 1.09-4.49, p = 0.022). The effect of peer education was greatest in dyads with children less than 1 year old at enrollment (34 % vs 12.7 %, RR 2.67, CI (1.22-5.86), p = 0.009).

CONCLUSIONS

Peer vaccine education can increase vaccine acceptance compared to routine care alone and may be particularly valuable in decreasing vaccination delays for younger infants. (Funded by EGL Charitable Foundation, ClinicalTrials.gov NCT05875779).

Coverage of Second Dose of Measles-Containing Vaccine (MCV-2) and Japanese Encephalitis Vaccine (JE-2) and Its Predictors Among Children 2-5 Years Old in the Ormanjhi Block of Ranchi, Jharkhand, India: A Mixed Method Study

Introduction Administering the measles vaccine at an appropriate age and dosage in children is important for India to eliminate measles, a potentially deadly vaccine-preventable disease. Similarly, the Japanese encephalitis (JE) vaccine, particularly in endemic regions is important to prevent morbidity and high-case fatality from the disease. The study attempts to evaluate the coverage of measles and JE vaccines and their predictors. Materials and methods A mixed method study design, incorporating a three-stage cluster random sampling process was used in the cross-sectional survey conducted among 604 children aged 2-5 years in the Ormanjhi block of Ranchi, Jharkhand, from April 2023 to June 2024. The parents/caregivers of the eligible children were interviewed using a predesigned, pretested semi-structured questionnaire, and the immunization status of children was taken from vaccination cards. A focused group discussion (FGD) and an in-depth interview (IDI) with healthcare providers formed the qualitative component. We conducted descriptive, and logistic regression analysis using the IBM SPSS Statistics for Windows, Version 26 (Released 2019; IBM Corp., Armonk, New York, United States). The association between the coverage of the vaccine and sociodemographic variables was done using the Chi-square test. Logistic regression was used to study the predictors, and a p-value of <0.05 was considered statistically significant. Results In the household survey, the coverage of the measles-containing vaccine first dose (MCV-1) was 594 (98.3%), while the second dose (MCV-2) was 536 (88.7%) out of 604 participants. For the JE vaccine, the coverage of the first dose (JE-1) was 588 (97.4%), while the second dose (JE-2) coverage was 492 (81.5%). In the multivariate logistic regression, religion and the lack of parental knowledge about measles were significant predictors for lower MCV-2 uptake, while the for JE vaccine, religion, father's education, and household head's occupation remained statistically significant factors (p ≤ 0.05). Vaccine hesitancy had mixed perceptions with the child's unavailability being the most significant reason for hesitancy in both MCV and JE vaccinations. In the FGD, child's unavailability at times of vaccination and parent's fear of side effects post vaccination were major factors for missing doses of the vaccine. Conclusion While the initial coverage of MCV and JE vaccines is commendable, the substantial drop in the second dose coverage and the delays in administration present significant challenges.

Determinants of measles second dose vaccination dropout among children aged 18-24 months in Ejere woreda, central Ethiopia; unmatched case-control study

Background

Measles continues to pose a significant public health challenge, especially in low- and middle-income countries. Despite the implementation of national vaccination programs, measles outbreaks persist in some parts of Ethiopia, and the determinants of dropout from the second measles vaccine dose are not well understood. Hence, this study aimed to assess determinants of measles second dose vaccination dropout among children aged 18-24 months in Ejere woreda, central Ethiopia.

Methods

A community-based unmatched case-control design was conducted in the Ejere Woreda of the Oromia regional state in Ethiopia between February 14 and April 6, 2023. Data were collected using a pre-tested structured questionnaire. The collected data were coded and entered into Epi-data version 3.1 and then transported to SPSS version 27 for statistical analysis. Descriptive analysis like frequency, mean, and percentage was calculated. Binary and multivariable logistic regression analysis was done. Finally, variables with a p-value <0.05 were considered statistically significant.

Result

A total of 446 mothers/caregivers, comprising 110 cases and 336 controls, participated in this study, making the response rate 97.8%. Lack of a reminder for the measles vaccine during postnatal care (PNC) (AOR = 5.19; 95% CI: 2.34, 7.83), having ≤2 antenatal care (ANC) contacts (AOR = 4.95; 95% CI: 2.86, 9.24), long waiting times during previous vaccination (AOR = 2.78; 95% CI: 1.19, 4.38), children of mothers/caregivers without formal education (AOR = 6.46; 95% CI: 2.81, 11.71), mothers/caregivers of children who were unaware of the importance of the second dose of measles (AOR = 8.37; 95% CI: 4.22, 15.08), and mothers/caregivers whose children did not receive at least two doses of vitamin A (AOR = 4.05; 95% CI: 2.15, 8.11) were significant determinants of measles second dose vaccination dropout.

Conclusion

Implementing targeted interventions during antenatal care and when mothers visit health facilities for other vaccines can significantly improve the uptake of the second dose of the measles vaccine. These strategies not only enhance overall vaccination coverage but also mitigate the risk of measles outbreaks in the community.

Information and vaccine hesitancy: The role of broadband Internet

We examine the effect of Internet diffusion on the uptake of an important public health intervention: the measles, mumps and rubella (MMR) vaccine. We study England between 2000 and 2011 when Internet diffusion spread rapidly and there was a high profile medical article (falsely) linking the MMR vaccine to autism. OLS estimates suggest Internet diffusion led to an increase in vaccination rates. This result is reversed after allowing for endogeneity of Internet access. The effect of Internet diffusion is sizable. A one standard deviation increase in Internet penetration led to around a 20% decrease in vaccination rates. Localities characterized by higher proportions of high skilled individuals and lower deprivation levels had a larger response to Internet diffusion. These findings are consistent with higher skilled and less-deprived parents responding faster to false information that the vaccine could lead to autism.

Unwelcome return: analyzing the recent rise of measles cases in the United States

Measles is a highly contagious viral illness mainly affecting the younger population worldwide despite the availability of a safe and effective vaccine. The disease is caused by measles virus, a member of the Paramyxoviridea family, which is transmitted through aerosols and respiratory droplets. Widespread vaccination has led to a significant decline in morbidity and mortality worldwide; however, recent years have witnessed a resurgence of outbreaks in the United States, highlighting barriers in achieving and sustaining elimination goals. The measles and rubella elimination initiative, under Immunization Agenda 2030, required at least 5 World Health Organization regions to achieve measles elimination by 2020, but none of the regions met these goals. Vaccine hesitancy, virus importation via international travel, and waning immunity are considered contributing factors to the recent surge of measles outbreaks. This review highlights the challenges in the pursuit of measles eradication and the importance of a multidimensional approach involving public health interventions.

Immunogenicity of a peptide-based vaccine for measles: a pilot evaluation in a mouse model

Although neutralizing antibody is an established correlate of protection for measles, T cell-mediated responses play at least two critical roles in immunity to measles: first, through provision of 'help' enabling robust humoral immune responses; and second, through clearance of measles virus-infected cells. Previously, we identified 13 measles-derived peptides that bound to human leukocyte antigen (HLA) molecules in Priess cells infected with measles virus. In this study, we evaluated the immunogenicity of these peptides in a transgenic mouse model. Our results demonstrated that these peptides induced Th1-biased immune responses at varying levels. Of the 13 peptides, the top four immunogenic peptides were further selected for a viral challenge study in mice. A vaccine based on a combination of these four peptides reduced morbidity and weight loss after viral challenge compared to placebo. Our results emphasize the potential of T cell-mediated, peptide-based vaccines against measles.

The Case for Assessing the Drivers of Measles Vaccine Uptake

Global measles cases are on the rise following disruptions to routine immunisation programs during the COVID-19 pandemic, with devastating consequences. According to the World Health Organization, the behavioural and social drivers of vaccination include what people think and feel about vaccines, social processes, motivation to vaccinate and practical barriers to vaccination. However, the drivers of measles vaccine uptake are not necessarily the same as those for other childhood vaccines, and we lack data on how these drivers specifically have changed during and since the COVID-19 pandemic. Without accurately measuring the behavioural and social drivers for measles vaccination, and ideally measuring them serially over time, countries cannot design, target and implement interventions that effectively increase and sustain measles vaccine coverage. This paper outlines what is and is not known about the behavioural and social drivers of measles vaccination and provides recommendations for improving their post-pandemic assessment.

Raising Epidemiological Awareness: Assessment of Measles/MMR Susceptibility in Highly Vaccinated Clusters within the Hungarian and Croatian Population-A Sero-Surveillance Analysis

Perceptions of the complete eradication of vaccine-preventable diseases such as measles, mumps, and rubella (MMR) may foster complacency and compromise vaccination efforts. Decreased measles vaccination rates during the COVID-19 pandemic have heightened the risk of outbreaks, even in adequately vaccinated populations. To address this, we have aligned with ECDC recommendations, leveraging previous cross-border sero-epidemiological assessments between Pécs, Hungary, and Osijek, Croatia, to identify latent risk groups and uncover potential parallels between our nations. Testing 2680 Hungarian and 1764 Croatian serum samples for anti-MMR IgG via ELISAs revealed anti-measles seropositivity ratios below expectations in Croatian cohorts aged ~20-30 (75.7%), ~30-40 (77.5%) and ~40-50 years (73.3%). Similarly, Hungarian samples also showed suboptimal seropositivity ratios in the ~30-40 (80.9%) and ~40-50 (87.3%) age groups. Considering mumps- and rubella-associated seropositivity trends, in both examined populations, individuals aged ~30-50 years exhibited the highest vulnerability. Additionally, we noted congruent seropositivity trends across both countries, despite distinct immunization and epidemiological contexts. Therefore, we propose expanding research to encompass the intricate dynamics of vaccination, including waning long-term immunity. This understanding could facilitate targeted interventions and bolster public awareness. Our findings underscore persistent challenges in attaining robust immunity against measles despite vaccination endeavors.

A Review of the Resurgence of Measles, a Vaccine-Preventable Disease, as Current Concerns Contrast with Past Hopes for Measles Elimination

On 22 February 2024, the World Health Organization (WHO) stated that, following the recent resurgence of measles cases in Europe, more than half the world's countries could expect significant measles outbreaks this year. Measles is a highly infectious virus with a primary case reproduction number (R0) of 12-18. Measles infection can be severe, resulting in pneumonia, and also more rarely in subacute sclerosing panencephalitis (SSPE), which occurs in 1 child out of every 1,000 and can be fatal. Until the 1990s, the hope of eliminating measles seemed possible following the successful development of effective vaccines, given individually or in the combined measles, mumps, and rubella (MMR) vaccine. Vaccine hesitancy due to misinformation about possible vaccine side effects, reduced vaccine uptake during and after the COVID-19 pandemic, and lack of awareness of the severe consequences of measles infection have contributed to low vaccine uptake, resulting in vulnerable communities. This article aims to review the recent resurgence of measles cases in the US, Europe, and the UK, to provide a reminder of the potential severity of measles, and to consider the causes of the failure to eliminate this vaccine-preventable viral infection.

Editorial: Global Health Concerns as Vaccine-Preventable Infections Including SARS-CoV-2 (JN.1), Influenza, Respiratory Syncytial Virus (RSV), and Measles Continue to Rise

In December 2023, the US Centers for Disease Control and Prevention (CDC) published the updated 2024 Advisory Committee on Immunization Practices (ACIP) Adult Immunization Schedule, which is available online for access by the public and healthcare professionals. These new guidelines come at a time when the incidence of vaccine-preventable viral infections from SARS-CoV-2 (JN.1), respiratory syncytial virus (RSV), influenza, and measles are increasing in adults and children due to vaccine hesitancy, or non-compliance. This editorial aims to highlight the ongoing global health concerns for the consequences of increasing reports of vaccine-preventable infections, including SARS-CoV-2 (JN.1), influenza, RSV, and measles, to understand the causes of vaccine hesitancy, and introduce some public health measures that could improve vaccine uptake.

Is Vaccination Approaching a Dangerous Tipping Point?

This Viewpoint discusses declining vaccination rates in the US, specifically against COVID-19, and the ways in which clinicians and the Food and Drug Administration can counter the current large volume of vaccine misinformation.

Mapping the Cognitive Biases Related to Vaccination: A Scoping Review of the Literature

INTRODUCTION

Human behavior and understanding of the vaccine ecosystem play a critical role in the vaccination decision-making process. The objective of this study was to understand different cognitive biases that may lead to vaccine acceptance or hesitancy.

METHODS

The eligibility criteria for this scoping review was vaccination-related cognitive bias studies published in the English language from inception to April 2022 and available on PubMed, Embase, and Google Scholar. It included all geographical locations and individuals of all age groups and excluded studies focusing on (i) clinical trials of vaccines, (ii) vaccine research conduct bias, (iii) cognitive delay, or (iv) statistical biases. The search method also included reviewing references in the retrieved articles.

RESULTS

Overall, 58 articles were identified, and after screening, 19 were included in this study. Twenty-one cognitive biases with the potential to affect vaccination decision-making were observed. These biases were further grouped into three broad categories: cognitive biases seen while processing vaccine-related information, during vaccination-related decision-making, and due to prior beliefs regarding vaccination.

CONCLUSIONS

This review identified critical cognitive biases affecting the entire process of vaccination that can influence research and public health efforts both positively and negatively. Recognizing and mitigating these cognitive biases is crucial for maintaining the population's level of trust in vaccination programs around the world.

Pervasive Parental Hesitancy and Resistance towards Measles Rubella Vaccination in Jordan

Measles remains a highly contagious and potentially severe infectious disease, necessitating high vaccine coverage. However, misinformation and measles vaccine hesitancy/resistance have posed significant challenges to achieving this goal. The COVID-19 pandemic further exacerbated these challenges, leading to a measles outbreak in Jordan in 2023. This study aimed to investigate the acceptance of the measles rubella (MR) vaccine among parents in Jordan and to identify its associated determinants. This cross-sectional questionnaire-based study was conducted using a previously Arabic-validated version of the Parental Attitudes towards Childhood Vaccines (PACV) survey instrument. Data collection took place in October 2023, and the final study sample comprised a total of 391 parents, with mothers representing 69.8% of the participants (n = 273). The majority of participating parents expressed either resistance (n = 169, 43.2%) or hesitancy (n = 168, 43.0%) towards MR vaccination, while only 54 participants (13.8%) expressed MR vaccine acceptance. Multivariate analysis revealed that trust in vaccine safety/efficacy, behavior, and having fewer offspring were significantly associated with MR vaccine acceptance. The current study revealed a concerning level of MR vaccine hesitancy/resistance among parents in Jordan, which could signal a public health alarm in the country. Urgent and targeted interventions are strongly recommended to address this issue, including mass campaigns aimed at building trust in the MR vaccine's safety/efficacy. Additionally, there is an urgent need for effective public health initiatives to ensure sufficient measles vaccine coverage to prevent future outbreaks of this serious disease.

Analysis of Parents' Attitudes and Knowledge toward Immunization and How These Factors Influence Their Decisions to Vaccinate Their Children against Human Papilloma Virus (HPV)

Background and objectives: Vaccination hesitancy is a growing problem associated with decreasing chances for the elimination of vaccine-preventable diseases through immunization. This research was conducted to learn about parents' attitudes toward vaccination, particularly against HPV, in the context of their beliefs and fears regarding immunization and the impact of these views on their children's vaccination decisions. An additional goal was to determine what views or convictions most often lead to the phenomenon of delaying or refusing vaccinations, especially HPV vaccines, in the surveyed community. Materials and Methods: An online questionnaire was conducted in which parents marked how they vaccinated their children with mandatory vaccinations and whether they took the opportunity to protect their children with additional vaccinations, including HPV and COVID-19. Respondents also marked the extent to which they agreed with the statements, regarding the safety of vaccinations, doubts about them, as well as popular anti-vaccine myths. Results: A total of 250 questionnaires were collected with data on the immunization of 425 children. Associations between specific beliefs and vaccine abstention were established. The most motivating factor for vaccination against HPV was the parent's awareness that the virus HP is the cause of cancer. The most inhibiting factor was respondent's compliance with the opinion that HPV vaccines can affect the child's sexual activity. Conclusions: The results indicate that information campaigns are needed, especially focusing on vaccine safety and the regularity and transparency of monitoring adverse effects. The obtained results will be used to create educational interventions against vaccination hesitancy more adapted to local conditions.

Factors Contributing to the Delayed Vaccination Among Children in Riyadh City, Saudi Arabia: A Cross-Sectional Study

Background Immunizations protect children from deadly infectious diseases. The timeliness of vaccinating children is crucial to ensure effective immunization and to decrease the burden of many infectious diseases. Therefore, this study assessed the prevalence and determinants of vaccination delay among children in Riyadh City, Saudi Arabia. Methods This cross-sectional study was conducted at the primary healthcare centers in Riyadh City, Saudi Arabia, on 593 parents with children of two years of age or below. It used a self-administered questionnaire inquiring about socio-demographic characteristics and assessing the vaccination statuses of their children and the causes of delayed vaccinations. Results The results showed that 7.1% of children had a delay in the previous vaccination. Of those delays, collectively, 77.5% were delays in inactivated poliovirus vaccine (IPV), oral poliovirus vaccine (OPV), and meningococcal vaccine (MCV) vaccines. The delay was mostly caused by an illness of the child on vaccination day, carelessness of parents, or long postponement. After adjusting for confounders, the father's high school or bachelor's education level (OR = 1.18, 95% CI: 1.03, 1.36) (p<0.05), child's mix-type nutrition (OR = 1.06, 95% CI: 1.02, 1.10) (p=0.001), and the belief that multiple vaccines are harmful to the child (POR = 1.03, 95% CI: 1.01, 1.06) (p=0.005) were positively associated with vaccination delay, while prematurity was negatively associated with vaccination delay (OR = 0.96, 95% CI: 0.93, 0.99) (p=0.031). Conclusion The study found the prevalence of vaccination delay was lower than in previous COVID-19-era studies. The child's illness was the main reason for the delay. Factors like parental education, nutrition type, and vaccine beliefs contributed to delays, while prematurity reduced delays. Measures should be strengthened to increase vaccination coverage for children.