Immunization Practices Research Articles

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023.

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023.

A Improving Birth-dose Hepatitis-B Vaccination in a Tertiary Level IV Neonatal Intensive Care Unit.

Perinatal hepatitis B is a global public health concern. To reduce perinatal hepatitis B and its complications, the Hepatitis B vaccine (HBV) is recommended by the New York State Department of Health and Advisory Committee on Immunization Practices within 24 hours of life for infants born with a birth weight ≥2000 g. Infants admitted to the neonatal intensive care unit (NICU) weighing over 2000 g missed their birth dose HBV frequently, which prompted the implementation of a quality improvement initiative to increase birth dose HBV immunization in a level IV NICU in New York. May 2019 to April 2021 baseline data showed the birth dose HBV rate of infants born ≥2000 g at 24% and 31% within 12 and 24 hours, respectively. The multidisciplinary QI team identified barriers using an Ishikawa cause-and-effect diagram. Our interventions included multidisciplinary collaboration, electronic medical record reminders, education, posters, and improved communication between staff and parents. We aimed to achieve a 25% improvement from the baseline. After 19 months of QI interventions (four Plan-Do-Study-Act cycles), the rate of administering birth dose HBV within 12 hours of life increased from 24% to 56% and within 24 hours from 31% to 64%. Process measure compliance improved, exceeding the 25% target, and showed sustained improvement. This QI initiative improved the rate of eligible infants receiving HBV within the first 24 hours of life in the NICU. This work can serve as a model for other healthcare institutions to improve HBV immunization rates in NICUs.

Pneumococcal Vaccination in Adults.

The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recently updated the adult pneumococcal vaccine recommendations to include two new pneumococcal conjugate vaccines (PCVs): PCV15 and PCV20. The authors review the updated guideline recommendations, their advantages and disadvantages, and nursing implications.

Recent Innovation in Niosomes-A Comprehensive review of advancements and Applications

The management of infectious diseases and immunization practices have experienced a revolutionary change in recent years. With the development of biotechnology and genetic engineering, not only have numerous biologicals targeted at certain diseases been created, but the focus has also been placed on the efficient delivery of these biologicals. As an alternative to liposomes, niosomes are vesicles made of non-ionic surfactants that are biodegradable, more harmless, more stable and less costly. This article summarizes various literature with the outcomes of the utilization of niosomes for different diseases.

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2023–24 Influenza Season

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2023–24 Influenza Season

A Qualitative Analysis of Social-Ecological Factors Shaping Childhood Immunisation Hesitancy and Delay in the Eastern Province of Saudi Arabia.

(1) Background: Immunisation is a crucial and effective method for preventing infectious diseases, with its success dependent on high immunisation rates to protect under-immunised individuals and promote herd immunity. This qualitative descriptive study is part of a larger explanatory sequential mixed method design that aims to explore factors influencing parents' decision making to complete childhood immunisation in the Eastern Province of Saudi Arabia, a country experiencing disparities in immunisation coverage across its population. (2) Methods: The sample consisted of a subset of participants from the initial quantitative phase, which included a survey on the immunisation attitudes of parents living in Qatif. This initial phase included n = 350 participants, who were over 18, had access to one of the 27 Primary Health Care (PHC) Centres in Qatif, and had a child under 24 months. This paper presents the qualitative-descriptive phase, which used a qualitative survey to gain open-ended responses from parents (n = 20) and analysed using thematic analysis. (3) Results: Participants identified certain vaccines, particularly MMR, as influencing their immunisation practices. Specific factors identified as deterring parents from immunising their children included fear of autism and other developmental delays, concerns about risks and side effects, mistrust in vaccine efficacy, and discouraging information from the media. Parents' immunisation decisions were evidently affected by policy compliance, family and friends, and social networking sites. These factors are explained through the socio-ecological model. Moreover, the COVID-19 pandemic influenced parents' decisions on vaccine completion in terms of perceived barriers, perceived benefits, and perceived trust. (4) Conclusions: By examining the social-ecological factors shaping parents' decisions to immunise their children in the Eastern Province of Saudi Arabia, this research contributes to the literature and informs the Saudi National Childhood Immunisation Programme about factors contributing to childhood immunisation hesitancy, helping to address a critical healthcare issue.

Association of Provider Recommendation and Receipt of Influenza Vaccine Among Pregnant Women by Race and Ethnicity.

Background: All pregnant women and those who may become pregnant are recommended by the Advisory Committee on Immunization Practices to receive the flu vaccine to prevent severe illness in the woman and infant. Despite the increased risk for complications in this population, flu vaccine uptake in pregnant women was 68.1% in the 2020-2021 flu season, with disparities by race and ethnicity. We sought to describe associations between provider recommendation with flu vaccine uptake by race and ethnicity in Tennessee women with a recent live birth. Materials and Methods: Weighted analysis used data from the 2016 to 2020 Tennessee Pregnancy Risk Assessment Monitoring System complex survey analysis procedures. Uptake was measured as receipt of flu vaccine in the 12 months before the most recent live birth, and positive recall of receiving provider advice to get the shot was the independent variable; for both we estimated 5-year averages stratified by race/ethnicity. Differences were assessed using chi-square tests. We modeled receipt of flu vaccine and estimated marginal predicted prevalence ratios (PRs); stratified models by race/ethnicity were constructed to estimate unadjusted and adjusted PRs. Results: The 5-year average for vaccine uptake before or during pregnancy was 56.7% but varied by race and ethnicity. Stratified bivariate analyses yielded different magnitudes of association by race/ethnicity between provider recommendation and flu vaccine receipt. After adjustment for payment source at delivery, marital status, age group, urbanicity, and maternal education, receiving a provider recommendation was strongly associated with flu vaccine uptake for all stratified models of pregnant women included in the study. The effect size was of a larger magnitude among non-Hispanic Black women, a population with a lower vaccine uptake. Conclusions: Given the association between provider recommendation and vaccine uptake in all groups, attention should be focused on increasing rates of provider recommendation.

Vaccine patterns among patients diagnosed with Guillain-Barré Syndrome and matched counterparts in a Medicare supplemental population, 2000–2020

Some vaccines have a small risk of Guillain-Barré Syndrome (GBS), a rare autoimmune disorder characterized by paralysis if untreated. The CDC’s Advisory Committee on Immunization Practices (ACIP) guidelines do not consider GBS a precaution for future vaccines unless GBS developed within six weeks after a tetanus-toxoid–containing vaccine or influenza vaccine. Our goal was to describe vaccine patterns before and after GBS diagnosis. We matched each of 709 patients diagnosed with GBS from 2002 to 2020 with Medicare supplemental insurance to 10 counterparts without GBS (1:10) on age and sex. Propensity score-based weighting balanced covariates between groups, and we estimated weighted mean cumulative counts (wMCC) of vaccines/person before and after GBS diagnosis. Among patients with GBS, 7% were diagnosed within 42 days after a vaccine. Prior to GBS diagnosis, the wMCC of vaccines per person was similar between GBS cases and matched counterparts, but after two years of follow-up, GBS patients received 21 fewer vaccines/100 people than counterparts (wMCC difference −0.21 vaccines/person, 95% CI −0.24 to −0.18); GBS patients received 16 vaccines/100 people while matched counterparts received 36/100. Vaccine use was reduced following GBS diagnosis despite no ACIP precaution for most (93%) patients in this study. The observed drop in vaccines after GBS diagnosis indicates a disconnect between clinical practice and current recommendations.

Vaccination practices in pediatric transplantation: A survey among member centers of the European reference network TransplantChild.

There is considerable variation in vaccination practices between pediatric transplant centers. This study aims to evaluate active immunization attitudes and practices among ERN-TransplantChild centers and identify potential areas of improvement that could be addressed by shared evidence-based protocols. A cross-sectional questionnaire of attitudes and practices toward immunization of pediatric SOT and HSCT candidates and recipients was sent to a representative member of multidisciplinary teams from 27 European centers belonging to the ERN-TransplantChild. A total of 28/62 SOT programs and 6/12 HSCT programs across 21 European centers participated. A quarter of centers did not have an on-site protocol for the immunizations. At the time of transplantation, pediatric candidates were fully immunized (80%-100%) in 57% and 33% of the SOT and HSCT programs. Variations in the time between vaccine administration and admission to the waiting list were reported between the centers, with 2 weeks for inactivated vaccines and variable time (2-4 weeks) for live-attenuated vaccines (LAVs). Almost all sites recommended immunization in the post-transplant period, with a time window of 4-8 months for the inactivated vaccines and 16-24 months for MMR and Varicella vaccines. Only five sites administer LAVs after transplantation, with seroconversion evaluated in 80% of cases. The immunization coverage of European pediatric transplant recipients is still inconsistent and far from adequate. This survey is a starting point for developing shared evidence-based immunization protocols for safe vaccination among pediatric transplant centers and generating new research studies.

Assessment of immunization session practices in primary health care centers in Al-Najaf province.

Immunization has played a vital role in improving global health by reducing the transmission of infectious diseases. To ensure the successful implementation of immunization programs, it is crucial to thoroughly examine various elements within the Primary Health Care Centers, including immunization session management, cold-chain and logistics management, supervision, and reporting. The study aims to assess the immunization session practices in selected primary healthcare centers in Al-Najaf governorate. A descriptive cross-sectional study was conducted at 26 primary healthcare centers, selected using simple random sampling, across six districts in Najaf governorate. A total of 143 healthcare workers, comprising 122 vaccinators and 21 doctors, were included in the study. questionnaires were utilized to assess immunization session practices. Data collection commenced on December 2, 2022, and concluded on March 2, 2023. Immunization session practices were evaluated as having poor vaccine and diluent management, fair cold chain management, communication with clients and caregivers, vaccine preparation and administration practices, and waste management practices. However, immunization session equipment availability, as well as card review and registration during immunization, received good evaluations. The overall assessment of immunization session practices was determined to be fair. In addition, the study identified significant associations between immunization practices and the number of non-vaccinators working in the immunization unit (P=0.035), and the average number of daily vaccine recipients in primary healthcare centers (P=0.046). The immunization session practices achieved a fair level of assessment, The increased number of daily visitors to the immunization unit and the number of health workers who are non-vaccinator in the unit affected negatively the immunization session practices.

Immunoinformatics for Novel Multi-Epitope Vaccine Development in Canine Parvovirus Infections.

Canine parvovirus (CPV-2) is one of the most important pathogens of dogs of all ages, causing pandemic infections that are characterized by fatal hemorrhagic enteritis. The CPV-2 vaccine is recommended as a core vaccine for pet animals. Despite the intensive practice of active immunization, CPV-2 remains a global threat. In this study, a multi-epitope vaccine against CPV-2 was designed, targeting the highly conserved capsid protein (VP2) via in silico approaches. Several immunoinformatics methods, such as epitope screening, molecular docking, and simulation were used to design a potential vaccine construct. The partial protein sequences of the VP2 gene of CPV-2 and protein sequences retrieved from the NCBI were screened to predict highly antigenic proteins through antigenicity, trans-membrane-topology screening, an allergenicity assessment, and a toxicity analysis. Homologous VP2 protein sequences typically linked to the disease were identified using NCBI BLAST, in which four conserved regions were preferred. Overall, 10 epitopes, DPIGGKTGI, KEFDTDLKP, GTDPDDVQ, GGTNFGYIG, GTFYFDCKP, NRALGLPP, SGTPTN, LGLPPFLNSL, IGGKTG, and VPPVYPN, were selected from the conserved regions to design the vaccine construct. The molecular docking demonstrated the higher binding affinity of these epitopes with dog leukocyte antigen (DLA) molecules. The selected epitopes were linked with Salmonella enterica flagellin FliC adjuvants, along with the PADRE sequence, by GGS linkers to construct a vaccine candidate with 272 nucleotides. The codon adaptation and in silico cloning showed that the generated vaccine can be expressed by the E. coli strain, K12, and the sequence of the vaccine construct showed no similarities with dog protein. Our results suggest that the vaccine construct might be useful in preventing canine parvoviral enteritis (CPE) in dogs. Further in vitro and in vivo experiments are needed for the validation of the vaccine candidate.

The wake of the triple epidemic (Tripledemic): does it emphasizes the COVID-19 vaccine as a routine immunization for children? - A cross-sectional study.

Many countries, including the USA, are currently confronting a triple epidemic in children as COVID-19 cases increase and new strains emerge which urge COVID-19 vaccination for children. The Advisory Committee on Immunization Practices (ACIP) for the CDC unanimously approved the inclusion of the COVID-19 vaccine (C19V) in the recommended immunizations. As healthcare professionals (HCPs) and parents are significant players in changing the trend of the triple epidemic by giving the C19V, the present study was done to determine awareness and perception of HCPs and parents on the tripledemic and the need for inclusion of C19V in vaccination schedules for children. A cross-sectional study was conducted among 400 HCPs and 200 parents to assess their knowledge and perception of tripledemic and the need for the inclusion of C19V. Noticeably, half of the participants had either recent personal (36.2%) or family (21.8%) exposure to some of the tripledemic like RSV, Flu, or COVID-19. On perceived awareness, 42% were concerned about tripledemic, and 35% thought that regular C19V may prevent or reduce tripledemic. Ironically, 11% were not willing to give C19V to their children. The logistic regression model for positive perception of tripledemic and regular C19V identified significant relationships with education (OR 2.19, CI 1.48-3.81), gender (OR 0.9, CI 01.02-2.63), recent personal or family exposure to any of the tripledemic (OR 0.239, CI 0.87-1.63) and presence of children in the family (OR 0.71, CI 1.4-1.96). The reason for favorable perception was preventing self and family from tripledemic. The findings may give insight to the policymakers for a strategic plan to include C19V in the routine schedule to combat the pandemic and tripledemic by improving herd immunity.

COVID-19 Vaccination Hesitancy in Autoimmune Disease Patients: Policy Action and Ethical Considerations.

As COVID-19 vaccination guidelines were issued by Advisory Committee on Immunization Practices (ACIP) and the Centers for Diseases Control and Prevention (CDC) across the US, each state and clinical provider instituted vaccine implementation and education policies and protocols for high-risk populations. However, current research has shown that while people with autoimmune diseases were listed by ACIP and CDC as a COVID-19 high-risk population, the rate of adherence to implementation and education protocols, as well as the prioritization of this sub-population as a high-risk group, varied among the clinicians and vaccinators thus impacting the hesitancy towards the COVID-19 vaccine and a correlation to low vaccination rates. The purpose of this review was to explore factors of COVID-19 vaccination hesitancy in people living with autoimmune diseases in relation to current implementation and education policies and protocols, as well as ethical and contextual factors, while providing possible implications. COVID-19 vaccine hesitancy in people living with autoimmune disease was greater than in the general population, as demonstrated by increased levels of overall mistrust and fear of potential risk and harmful side effects. Evidence has shown that COVID-19 vaccination is safe and effective for patients with autoimmune diseases. Additionally, the benefits of COVID-19 vaccination outweigh its potential risks and adverse effects in this population. However, the non-adherence to policy and protocols, especially community education protocols, by those providing the vaccination have a negative impact on the overall perception of the vaccine and needs to be addressed at local and state levels in order to protect this population. Future research should provide strategies to guide collaborative efforts between government and local agencies in providing tailored vaccination campaigns to this population. In parallel with policy, COVID-19 vaccination intervention implementation and educational protocols should be developed with evidence-based guidelines for public health and clinical professionals that are targeted at this vulnerable high-risk population.

Use of Respiratory Syncytial Virus Vaccines in Older Adults: Recommendations of the Advisory Committee on Immunization Practices - United States, 2023.

Respiratory syncytial virus (RSV) is a cause of severe respiratory illness in older adults. In May 2023, the Food and Drug Administration approved the first vaccines for prevention of RSV-associated lower respiratory tract disease in adults aged ≥60 years. Since May 2022, the Advisory Committee on Immunization Practices (ACIP) Respiratory Syncytial Virus Vaccines Adult Work Group met at least monthly to review available evidence regarding the safety, immunogenicity, and efficacy of these vaccines among adults aged ≥60 years. On June 21, 2023, ACIP voted to recommend that adults aged ≥60 years may receive a single dose of an RSV vaccine, using shared clinical decision-making. This report summarizes the body of evidence considered for this recommendation and provides clinical guidance for the use of RSV vaccines in adults aged ≥60 years. RSV vaccines have demonstrated moderate to high efficacy in preventing RSV-associated lower respiratory tract disease and have the potential to prevent substantial morbidity and mortality among older adults; postmarketing surveillance will direct future guidance.

Trends and Opportunities: Hepatitis A Virus Infection, Seroprevalence, and Vaccination Coverage-United States, 1976-2020.

The incidence of hepatitis A declined in the United States following the introduction of hepatitis A vaccines, before increasing in the setting of recent widespread outbreaks associated with person-to-person transmission. We describe the hepatitis A epidemiology in the United States, identify susceptible populations over time, and demonstrate the need for improved hepatitis A vaccination coverage, especially among adults at increased risk for hepatitis A. We calculated the hepatitis A incidence rates for sociodemographic characteristics and percentages for risk factors and clinical outcomes for hepatitis A cases reported to the National Notifiable Diseases Surveillance System during 1990-2020. We generated nationally representative estimates and 95% CIs of hepatitis A seroprevalence during 1976-March 2020 and self-reported hepatitis A vaccination coverage during 1999-March 2020 for the noninstitutionalized civilian US population using data from the National Health and Nutrition Examination Survey. Overall, the rate per 100 000 population of reported cases of hepatitis A virus infection in the United States declined 17.3-fold, from 10.4 during 1990-1998 to 0.6 during 2007-2015, and then increased to 2.8 during 2016-2020. The overall hepatitis A seroprevalence in the United States increased from 38.2% (95% CI, 36.2%-40.1%) during 1976-1980 to 47.3% (95% CI, 45.4%-49.2%) during 2015-March 2020. The prevalence of self-reported hepatitis A vaccination coverage in the United States increased more than 2.5-fold, from 16.3% (95% CI, 15.0%-17.7%) during 1999-2006 to 41.9% (95% CI, 40.2%-43.7%) during 2015-March 2020. Hepatitis A epidemiology in the United States changed substantially during 1976-2020. Improved vaccination coverage, especially among adults recommended for vaccination by the Advisory Committee on Immunization Practices, is vital to stop current hepatitis A outbreaks associated with person-to-person transmission in the United States and prevent similar future recurrences.

Pneumococcal vaccine uptake among Medicare Beneficiaries aged ≥65 years following the shared clinical decision-making recommendation for 13-valent pneumococcal conjugate vaccine in 2019

BackgroundIn November 2019, the US Advisory Committee on Immunization Practices recommended shared clinical decision-making (SCDM) for use of 13-valent pneumococcal conjugate vaccine (PCV13) among immunocompetent elderly adults. The impact of SCDM on PCV13 use in this population, immunocompromised persons, and vulnerable subgroups has not been well documented. MethodsUsing Medicare Research Identifiable Files (01/2018 – 09/2020), monthly uptake of pneumococcal vaccine (PCV13, 23-valent pneumococcal polysaccharide vaccine [PPSV23]) was identified among fee-for-service beneficiaries aged ≥ 65 years with Part B coverage and no evidence of prior PCV13. Uptake was stratified by vaccine, risk profile, and demographics. ResultsAmong the > 12 M beneficiaries included each month, PCV13 uptake declined from > 70% of pneumococcal vaccinations before SCDM to < 60% after SCDM (02/2020). Reductions in PCV13 uptake were consistent across vulnerable subgroups as well as immunocompromised persons. ConclusionsPCV13 use decreased among immunocompetent and immunocompromised persons alike, despite continued routine PCV13 recommendation for the latter group.

Public health impact of the U.S. Scenario Modeling Hub

Beginning in December 2020, the COVID-19 Scenario Modeling Hub has provided quantitative scenario-based projections for cases, hospitalizations, and deaths, aggregated across up to nine modeling groups. Projections spanned multiple months into the future and provided timely information on potential impacts of epidemiological uncertainties and interventions. Projections results were shared with the public, public health partners, and the Centers for Disease Control COVID-19 Response Team. The projections provided insights on situational awareness and informed decision-making to mitigate COVID-19 disease burden (e.g., vaccination strategies). By aggregating projections from multiple modeling teams, the Scenario Modeling Hub provided rapidly synthesized information in times of great uncertainty and conveyed possible trajectories in the presence of emerging variants. Here we detail several use cases of these projections in public health practice and communication, including assessments of whether modeling results directly or indirectly informed public health communication or guidance. These include multiple examples where comparisons of projected COVID-19 disease outcomes under different vaccination scenarios were used to inform Advisory Committee for Immunization Practices recommendations. We also describe challenges and lessons learned during this highly beneficial collaboration.

PREVALENCE AND ASSOCIATED RISK FACTORS OF MALNUTRITION AMONG UNDER FIVE YEARS OF CHILDREN IN THE FIELD PRACTICE AREA OF RURAL HEALTH TRAINING CENTRE, NAILA JAIPUR

Objective: Malnutrition among children under the age of five is a global health concern, particularly in developing countries. In India, prevalent nutritional problems include stunting, wasting, anemia, poverty, and low birth weight. These forms of malnutrition have severe consequences for children's health and overall well-being, making malnutrition a leading risk factor for children under five worldwide. Efforts to address malnutrition in developing countries, including India, have been a focus of United Nations' Millennium Development Goals (MDGs) aimed at improving child health outcomes. However, despite these efforts, malnutrition remains a significant concern, particularly among women and children in India.&#x0D; Methods: The study was conducted in the rural community of Jamuwaramgarh block in Rajasthan, Jaipur District, India. The sample size was calculated based on a prevalence rate of malnutrition among under-five children. Ethical approval was obtained, and only mothers with children aged 6-59 mo were included in the study. A multistage sampling procedure was used to select the study participants, including sub-block, primary health centers, villages, and households. Data on socio-demographic characteristics, obstetric history, immunization, breastfeeding, and weaning practices were collected through interviews. Anthropometric measurements were taken, and the data were entered into Microsoft Excel for analysis.&#x0D; Results: The study included 700 children under the age of five. The prevalence of malnutrition among children in the study area was determined. The data collected on socio-demographic characteristics, obstetric history, and other variables were analyzed to identify the determinants of malnutrition among rural Indian children.&#x0D; Conclusion: Malnutrition among children under the age of five remains a significant public health concern, particularly in developing countries like India. Stunting and wasting are prevalent forms of malnutrition, with serious consequences for children's growth and development. Despite efforts to address the issue, progress has been slow, and the prevalence of malnutrition in India is still alarmingly high.

Interim Recommendations for Use of Bivalent mRNA COVID-19 Vaccines for Persons Aged ≥6 Months — United States, April 2023

Throughout the national public health emergency declared in response to the COVID-19 pandemic, CDC, guided by the Advisory Committee on Immunization Practices (ACIP), has offered evidence-based recommendations for the use of COVID-19 vaccines in U.S. populations after each regulatory action by the Food and Drug Administration (FDA). During August 2022-April 2023, FDA amended its Emergency Use Authorizations (EUAs) to authorize the use of a single, age-appropriate, bivalent COVID-19 vaccine dose (i.e., containing components from the ancestral and Omicron BA.4/BA.5 strains in equal amounts) for all persons aged ≥6 years, use of bivalent COVID-19 vaccine doses for children aged 6 months-5 years, and additional bivalent doses for immunocompromised persons and adults aged ≥65 years (1). ACIP voted in September 2022 on the use of the bivalent vaccine, and CDC made recommendations after the September vote and subsequently, through April 2023, with input from ACIP. This transition to a single bivalent COVID-19 vaccine dose for most persons, with additional doses for persons at increased risk for severe disease, facilitates implementation of simpler, more flexible recommendations. Three COVID-19 vaccines are currently available for use in the United States and recommended by ACIP: 1) the bivalent mRNA Pfizer-BioNTech COVID-19 vaccine, 2) the bivalent mRNA Moderna COVID-19 vaccine, and 3) the monovalent adjuvanted, protein subunit-based Novavax COVID-19 vaccine.* As of August 31, 2022, monovalent mRNA vaccines based on the ancestral SARS-CoV-2 strain are no longer authorized for use in the United States (1).

Safety Monitoring of mRNA COVID-19 Vaccine Third Doses Among Children Aged 6 Months–5 Years — United States, June 17, 2022–May 7, 2023

As of May 7, 2023, CDC's Advisory Committee on Immunization Practices (ACIP) recommends that all children aged 6 months-5 years receive at least 1 age-appropriate bivalent mRNA COVID-19 vaccine dose. Depending on their COVID-19 vaccination history and history of immunocompromise, these children might also need additional doses* (1-3). Initial vaccine safety findings after primary series vaccination among children aged 6 months-5 years showed that transient local and systemic reactions were common whereas serious adverse events were rare (4). To characterize the safety of a third mRNA COVID-19 vaccine dose among children aged 6 months-5 years, CDC reviewed adverse events and health surveys reported to v-safe, a voluntary smartphone-based U.S. safety surveillance system established by CDC to monitor health after COVID-19 vaccination (https://vsafe.cdc.gov/en/) and the Vaccine Adverse Event Reporting System (VAERS), a U.S. passive vaccine safety surveillance system co-managed by CDC and the Food and Drug Administration (FDA) (https://vaers.hhs.gov/) (5). During June 17, 2022-May 7, 2023, approximately 495,576 children aged 6 months-4 years received a third dose (monovalent or bivalent) of Pfizer-BioNTech vaccine and 63,919 children aged 6 months-5 years received a third dose of Moderna vaccine.† A third mRNA COVID-19 vaccination was recorded for 2,969 children in v-safe; approximately 37.7% had no reported reactions, and among those for whom reactions were reported, most reactions were mild and transient. VAERS received 536 reports after a third dose of mRNA COVID-19 vaccine for children in these age groups; 98.5% of reports were nonserious and most (78.4%) were classified as a vaccination error.§ No new safety concerns were identified. Preliminary safety findings after a third dose of COVID-19 vaccine for children aged 6 months-5 years are similar to those after other doses. Health care providers can counsel parents and guardians of young children that most reactions reported after vaccination with Pfizer-BioNTech or Moderna vaccine were mild and transient and that serious adverse events are rare.