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.

2022 Polio outbreak, Rockland County, NY: Cost evaluation of strategies to prevent future outbreaks of vaccine-preventable diseases.

In 1994, the World Health Organization Region of the Americas was declared polio-free. In July 2022, a confirmed case of paralytic polio in an unvaccinated adult resident of Rockland County, New York was reported by the New York State Department of Health (NYSDOH) and Rockland County Department of Health (RCDOH). While only one case was identified, a single case of paralytic polio represents a public health emergency in the United States. The patient's county of residence was identified to have low vaccination coverage indicating that the community was at risk for additional cases. Disease outbreaks are resource-intensive and incur high costs to the patient, local health departments, and to society. These costs are potentially avoidable for vaccine-preventable diseases and thus, highlight the urgency to not only interrupt transmission but to prevent future vaccine-preventable disease outbreaks by improving vaccination coverage. Following case confirmation, an investigation and response was initiated by NYSDOH, along with local health departments and the Centers for Disease Control and Prevention (CDC). After the initial investigation and response, collaborative efforts to mitigate risk and strengthen routine immunization continued, which included provider outreach and immunization record assessments of Head Start and licensed childcare facilities (primarily those with missing or incomplete required vaccination coverage reports from the previous year) in Rockland County. We estimated the costs of (1) provider outreach and (2) childcare and pre-kindergarten immunization record assessments of select licensed childcare and Head Start facilities in Rockland County. The total labor cost incurred for these activities was $138,514 with a total of 2,555 h incurred. Often there are unique opportunities in the midst of an outbreak for public health to implement activities to proactively address low vaccination and strengthen vaccination coverage and possibly prevent future outbreaks. Understanding the cost of these activities might help inform future outbreak planning.

Entangled epidemics: tackling vaccine-preventable diseases in the era of frequent epidemics in Africa.

Whilst the largely limited health system and funds are already overstretched while responding to multiple epidemics, ongoing vaccine-preventable diseases (VPD) including polio and measles continue to be a public health threat and expose the weaknesses of the public health system in many African countries. The surge in VPD outbreaks during epidemics appears to be a common trend in Africa, often due to reduced vaccination coverage. The World Health Organization reported that, in 2021, nearly 25 million children missed their first measles dose, 5 million more than in 2019. The drop in childhood immunizations was partly attributed to the COVID-19 pandemic which has caused significant interruption in public health services delivery and reduced vaccination coverage. Vaccines help reduce the incidence of VPD. Therefore, effective VPD outbreak response mechanisms and strategies that include ramping up catch-up campaigns for immunization during epidemic troughs including the provision of vaccines outside clinics as well as assessing newer vaccine delivery models during pandemics are essential to minimize the impact of VPD outbreaks during emerging epidemics. Ensuring access to vaccines to address outbreaks and provide supplemental vaccination is essential if we are to be a VPD-free region.

Modelling outbreak response impact in human vaccine-preventable diseases: A systematic review of differences in practices between collaboration types before COVID-19.

BACKGROUND: Outbreak response modelling often involves collaboration among academics, and experts from governmental and non-governmental organizations. We conducted a systematic review of modelling studies on human vaccine-preventable disease (VPD) outbreaks to identify patterns in modelling practices between two collaboration types. We complemented this with a mini comparison of foot-and-mouth disease (FMD), a veterinary disease that is controllable by vaccination. METHODS: We searched three databases for modelling studies that assessed the impact of an outbreak response. We extracted data on author affiliation type (academic institution, governmental, and non-governmental organizations), location studied, and whether at least one author was affiliated to the studied location. We also extracted the outcomes and interventions studied, and model characteristics. Included studies were grouped into two collaboration types: purely academic (papers with only academic affiliations), and mixed (all other combinations) to help investigate differences in modelling patterns between collaboration types in the human disease literature and overall differences with FMD collaboration practices. RESULTS: Human VPDs formed 227 of 252 included studies. Purely academic collaborations dominated the human disease studies (56%). Notably, mixed collaborations increased in the last seven years (2013-2019). Most studies had an author affiliated to an institution in the country studied (75.2%) but this was more likely among the mixed collaborations. Contrasted to the human VPDs, mixed collaborations dominated the FMD literature (56%). Furthermore, FMD studies more often had an author with an affiliation to the country studied (92%) and used complex model design, including stochasticity, and model parametrization and validation. CONCLUSION: The increase in mixed collaboration studies over the past seven years could suggest an increase in the uptake of modelling for outbreak response decision-making. We encourage more mixed collaborations between academic and non-academic institutions and the involvement of locally affiliated authors to help ensure that the studies suit local contexts.

Vaccine Preventable Disease and Vaccine Hesitancy.

Global immunization programs have saved tens of millions of lives over the last 2 decades. Now, the recent successes of COVID-19 vaccines having saved more than 3 million lives in North America during the pandemic may open the door to accelerate technologies for other emerging infection vaccines. New vaccines for respiratory syncytial virus, norovirus, influenza, herpes simplex virus, shingles, dengue fever, enteric bacterial infections, malaria, and Chagas disease are advancing through clinical development and could become ready for delivery over the next 5 years. The successful delivery of these new vaccines may require expanded advocacy and communications efforts.

Introducing seasonal influenza vaccine in Bhutan: Country experience and achievements.

Bhutan successfully introduced multiple vaccines since the establishment of the Vaccine Preventable Disease Program in 1979. Surveillance and subsequent introduction of influenza vaccination became a public health priority for the Ministry of Health following the influenza A(H1N1)pdm09 pandemic. Sentinel surveillance for influenza in Bhutan began in 2008, and a study of severe acute respiratory infection was conducted in 2017, which found the highest influenza burden in children aged <5 years and adults ≥50 years. Following review of surveillance and burden of disease data, the National Technical Advisory Group presented recommendations to Bhutan's Ministry of Health which approved influenza vaccine introduction for all five high-risk groups in the country. Upon the official launch of the program in June 2018, the Vaccine Preventable Disease Program began planning, budgeting, and procurement processes with technical and financial support from the Partnership for Influenza Vaccine Introduction, the United States Centers for Disease Control and Prevention, the Bhutan Health Trust Fund, and the World Health Organization. Influenza vaccination for high-risk groups was integrated into Bhutan's routine immunization services in all health care facilities beginning in November 2019 and vaccinated all populations in 2020 in response to the COVID-19 pandemic. Coverage levels between 2019 and 2022 were highest in children aged 6-24 months (62.5%-96.9%) and lowest in pregnant women (47.7%-62.5%). Bhutan maintained high coverage levels despite the COVID-19 pandemic by continued provision of influenza vaccine services at health centers during lockdowns, conducting communication and sensitization efforts, and using catch-up campaigns. Bhutan's experience with introducing and scaling up the influenza vaccine program contributed to the country's capacity to rapidly deploy its COVID-19 vaccination program in 2021.

Risks of low vaccination coverage and strategies to prevent the resurgence of vaccine-preventable diseases in infants in the COVID-19 pandemic scenario: recommendations for Latin America and the Caribbean by the group of experts on infant immunization for Latin America.

INTRODUCTION: The WHO 2030 Immunization Agenda (IA-2030) harmonizes immunization activity plans at community, national, regional and global levels. Additionally, medical societies play an important role. The Latin American Group of Experts on Infant Immunization, established in 2018, advises on the harmonization, update, and optimization of infant vaccination programs in Latin America and the Caribbean (LAC). In September 2021, 41 such experts from 13 LAC countries met to develop recommendations for increasing regional vaccination coverage to avoid the reemergence of vaccine-preventable diseases and/or the occurrence of outbreaks. AREAS COVERED: The following items were evaluated: (i) immunization challenges before and during the COVID-19 pandemic; (ii) the status of current immunization programs, particularly infant pertussis and polio vaccination; (iii) possible solutions for overcoming vaccination challenges and achieving regional vaccination coverage targets. EXPERT OPINION/COMMENTARY: Medical societies provide valuable recommendations to guide and update vaccination schedules. In the LAC region, possible strategies to achieve target vaccination rates include the use of combination vaccines, strengthening surveillance systems, improving school attendance, advancing vaccine education and confidence, striving for vaccination equity, widening operational capacity, creating strategic alliances, and strengthening the role of medical groups. It is hoped that these recommendations will be implemented in the LAC region.

[Transmission risk classification for vaccine-preventable diseases in Minas Gerais, Brazil: two years since the onset of the COVID-19 pandemic]. / Classificação de risco para transmissão de doenças imunopreveníveis em Minas Gerais, Brasil: dois anos desde o início da pandemia de COVID-19.

The scope of this study is to analyze the risk classification of transmission of vaccine-preventable diseases (VPDs) in the 853 municipalities in the state of Minas Gerais (MG) two years after the onset of the COVID-19 pandemic. It is an epidemiological study with secondary data on vaccination coverage and dropout rate of ten immuno-biologicals recommended for under 2-year-old children in 2021 in MG. With respect to the dropout rate, this indicator was only evaluated for the multidose vaccines. After calculating all the indicators, the municipalities of the state were classified according to the transmission risk of VPDs into five categories: very low, low, medium, high, and very high risk. Minas Gerais had 80.9% of municipalities classified as high transmission risk for VPDs. Regarding the homogeneity of vaccination coverage (HCV), large municipalities had the highest percentage of HCV classified as very low, and 100% of these municipalities were classified as high or very high risk for transmission of VPDs, with statistical significance. The use of immunization indicators by municipality is effective for the classification of the scenario of each territory and the proposal of public policies seeking to increase vaccination coverage.

O objetivo é analisar a classificação de risco de transmissão de doenças imunopreveníveis nos 853 municípios de Minas Gerais (MG) após dois anos de início da pandemia de COVID-19. Estudo epidemiológico com dados secundários da cobertura vacinal e taxa de abandono de dez imunobiológicos recomendados para crianças menores de 2 anos, no ano de 2021, em MG. Em relação à taxa de abandono, este indicador foi avaliado somente para as vacinas multidoses. Após o cálculo de todos os indicadores, os municípios do estado foram classificados de acordo com o risco de transmissão de doenças imunopreveníveis em cinco estratos. Minas Gerais apresentou 80,9% dos municípios classificados como alto risco para transmissão de doenças imunopreveníveis. Em relação à homogeneidade das coberturas vacinais (HCV), os municípios de grande porte apresentaram a maior porcentagem de HCV classificada como muito baixa e 100% desses municípios foram classificados como de alto ou muito alto risco para transmissão de doenças imunopreveníveis, com significância estatística. A utilização de indicadores de imunização por município é efetiva para o delineamento do cenário de cada território e a proposição de políticas públicas em saúde visando o aumento das coberturas vacinais.

Willingness to get vaccinated against influenza, pneumococcal disease, pertussis, and herpes zoster - A pre-COVID-19 exploration among the older adult population.

BACKGROUND: Older adults are at increased risk for adverse health outcomes when having an influenza, pneumococcal disease, pertussis, or herpes zoster infection. Despite the ability of vaccinations to prevent these adverse outcomes, vaccination coverage is low in the European Union. This study aimed to explore the sociodemographic, lifestyle, and health-related characteristics associated with vaccination willingness for these vaccine-preventable diseases. METHODS: Cross-sectional data from wave 6 (years 2013-2017) of the population-based Doetinchem Cohort Study was analysed, with 3063 participants aged 46-86 years included. The outcome was the self-reported willingness to get vaccinated against influenza, pneumococcal disease, pertussis, and herpes zoster (willing, neutral, not willing). Multinomial logistic regression was used to investigate the socio-demographic, lifestyle and health characteristics associated with vaccination willingness. RESULTS: For influenza 36 % was willing to get vaccinated, 35 % was neutral and 28 % was not willing to get vaccinated. The willingness to get vaccinated for the relatively unfamiliar vaccine-preventable diseases was lower: 26 % for pneumococcal disease (neutral: 50 %, not willing: 23 %), 26 % for pertussis (neutral 53 %, not willing: 22 %), and 23 % for herpes zoster (neutral 54 %, not willing: 24 %). A relative lower willingness was found among those 46-64 years old (compared to those 65 years or older). Women, having a high SES, being employed and having a good health were all associated with lower willingness to get vaccinated, which was the case for all vaccine-preventable diseases. CONCLUSIONS: Older adults were generally more willing to get vaccinated against influenza than for the three less familiar diseases. Characteristics of those less willing may be used to improve strategies to increase vaccination coverage. Additional studies are needed to investigate the willingness to get vaccinated during and after the COVID-19 pandemic that may have changed the feel of urgency for vaccination.

Effects of COVID-19 on Vaccine-Preventable Disease Surveillance Systems in the World Health Organization African Region, 2020.

Global emergence of the COVID-19 pandemic in 2020 curtailed vaccine-preventable disease (VPD) surveillance activities, but little is known about which surveillance components were most affected. In May 2021, we surveyed 214 STOP (originally Stop Transmission of Polio) Program consultants to determine how VPD surveillance activities were affected by the COVID-19 pandemic throughout 2020, primarily in low- and middle-income countries, where program consultants are deployed. Our report highlights the responses from 154 (96%) of the 160 consultants deployed to the World Health Organization African Region, which comprises 75% (160/214) of all STOP Program consultants deployed globally in early 2021. Most survey respondents observed that VPD surveillance activities were somewhat or severely affected by the COVID-19 pandemic in 2020. Reprioritization of surveillance staff and changes in health-seeking behaviors were factors commonly perceived to decrease VPD surveillance activities. Our findings suggest the need for strategies to restore VPD surveillance to prepandemic levels.

Emergence of Vaccine-Preventable Diseases: The Perfect Storm of Hesitancy, Refusal, a Pandemic, and War.

The landscape of pediatric vaccination has changed dramatically due to changing attitudes toward immunizations and recent world events. The rise of vaccine hesitancy and refusal related to the concurrent rise of social media and anti-vaccination messages with misinformation campaigns have led to populations of children being unimmunized or under-immunized. These populations have been left vulnerable to the rapid spread of vaccine-preventable infection. Additionally, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the clinical syndrome known as coronavirus disease 2019 (COVID-19) resulted in the emergence of a worldwide pandemic. Control measures to mitigate the spread of COVID-19 resulted in numerous reports of children missing routine vaccines along with the stopping of many public health immunization programs. Finally, armed conflicts and war have led to large family migrations from their homelands to various countries and regions leading to increased risk for missed maternal and child immunization as well as difficulty in keeping vaccination records. [Pediatr Ann. 2022;51(11):e426-e430.].

Comprehensive Vaccine-Preventable Disease Surveillance in the Western Pacific Region: A Literature Review on Integration of Surveillance Functions, 2000-2021.

INTRODUCTION: A strategic framework for 2021-2030 developed by the World Health Organization (WHO) Regional Office for the Western Pacific emphasizes the need for high-quality and integrated vaccine-preventable disease (VPD) surveillance. We conducted a literature review to document the barriers, enabling factors, and innovations for integrating surveillance functions for VPDs and other communicable diseases in Western Pacific Region (WPR) countries. METHODS: We searched published and gray literature on integrated VPD surveillance from 2000 to 2021. Articles in English, Spanish, or French were screened to identify those relating to VPD surveillance in a WPR country and not meeting defined exclusion criteria. We categorized articles using the 8 WHO surveillance support functions and abstracted data on the country; type of surveillance; and reported barriers, enabling factors, and best practices for integration. RESULTS: Of the 3,137 references screened, 87 met the eligibility criteria. Of the 8 surveillance support functions, the proportion of references that reported integration related to the laboratory was 56%, followed by workforce capacity (54%), governance (51%), data management and use (47%), field logistics and communication (47%), coordination (15%), program management (13%), and supervision (9%). Several references noted fragmented systems and a lack of coordination between units as barriers to integration, highlighting the importance of engagement across public health units and between the public and private sectors. The literature also indicated a need for interoperable information systems and revealed the use of promising new technologies for data reporting and laboratory testing. In some WPR countries, workforce capacity was strengthened at all administrative levels by the implementation of integrated trainings on data monitoring and use and on laboratory techniques applicable to multiple VPDs. CONCLUSION: This literature review supports integrating VPDs into broader communicable disease surveillance systems in WPR countries while ensuring that the minimal WHO-recommended standards for VPD surveillance are met.

Impact of Routine Childhood Immunization in Reducing Vaccine-Preventable Diseases in the United States.

BACKGROUND AND OBJECTIVES: Current routine immunizations for children aged ≤10 years in the United States in 2019 cover 14 vaccine-preventable diseases. We characterize the public-health impact of vaccination by providing updated estimates of disease incidence with and without universally recommended pediatric vaccines. METHODS: Prevaccine disease incidence was obtained from published data or calculated using annual case estimates from the prevaccine period and United States population estimates during the same period. Vaccine-era incidence was calculated as the average incidence over the most recent 5 years of available surveillance data or obtained from published estimates (if surveillance data were not available). We adjusted for underreporting and calculated the percent reduction in overall and age-specific incidence for each disease. We multiplied prevaccine and vaccine-era incidence rates by 2019 United States population estimates to calculate annual number of cases averted by vaccination. RESULTS: Routine immunization reduced the incidence of all targeted diseases, leading to reductions in incidence ranging from 17% (influenza) to 100% (diphtheria, Haemophilus influenzae type b, measles, mumps, polio, and rubella). For the 2019 United States population of 328 million people, these reductions equate to >24 million cases of vaccine-preventable disease averted. Vaccine-era disease incidence estimates remained highest for influenza (13 412 per 100 000) and Streptococcus pneumoniae-related acute otitis media (2756 per 100 000). CONCLUSIONS: Routine childhood immunization in the United States continues to yield considerable sustained reductions in incidence across all targeted diseases. Efforts to maintain and improve vaccination coverage are necessary to continue experiencing low incidence levels of vaccine-preventable diseases.

COVID-19 impact on routine immunisations for vaccine-preventable diseases: Projecting the effect of different routes to recovery.

Over the past two decades, vaccination programmes for vaccine-preventable diseases (VPDs) have expanded across low- and middle-income countries (LMICs). However, the rise of COVID-19 resulted in global disruption to routine immunisation activities. Such disruptions could have a detrimental effect on public health, leading to more deaths from VPDs, particularly without mitigation efforts. Hence, as routine immunisation activities resume, it is important to estimate the effectiveness of different approaches for recovery. We apply an impact extrapolation method developed by the Vaccine Impact Modelling Consortium to estimate the impact of COVID-19-related disruptions with different recovery scenarios for ten VPDs across 112 LMICs. We focus on deaths averted due to routine immunisations occurring in the years 2020-2030 and investigate two recovery scenarios relative to a no-COVID-19 scenario. In the recovery scenarios, we assume a 10% COVID-19-related drop in routine immunisation coverage in the year 2020. We then linearly interpolate coverage to the year 2030 to investigate two routes to recovery, whereby the immunization agenda (IA2030) targets are reached by 2030 or fall short by 10%. We estimate that falling short of the IA2030 targets by 10% leads to 11.26% fewer fully vaccinated persons (FVPs) and 11.34% more deaths over the years 2020-2030 relative to the no-COVID-19 scenario, whereas, reaching the IA2030 targets reduces these proportions to 5% fewer FVPs and 5.22% more deaths. The impact of the disruption varies across the VPDs with diseases where coverage expands drastically in future years facing a smaller detrimental effect. Overall, our results show that drops in routine immunisation coverage could result in more deaths due to VPDs. As the impact of COVID-19-related disruptions is dependent on the vaccination coverage that is achieved over the coming years, the continued efforts of building up coverage and addressing gaps in immunity are vital in the road to recovery.

Effect of COVID-19 restrictions and border closures on vaccine preventable diseases in Victoria, Australia, 2020-2021.

Background: In 2020, Victoria introduced multiple interventions aimed at containing the spread of coronavirus disease 2019 (COVID-19). We examine the effect of these restrictions on other vaccine preventable diseases (VPDs). Methods: We analysed the mandatory reporting data, notified to the Victorian Department of Health, for VPDs from January 2015 to December 2021. Results: Reductions in notifications were seen for most notifiable VPDs. A precipitous decline in influenza and measles notifications was recorded in April 2020, which was sustained for both diseases throughout 2020-2021. Notifications for chickenpox, invasive meningococcal disease, invasive pneumococcal disease, and pertussis were reduced by greater than 50% from the 2015-2019 average. No notified cases of diphtheria, poliomyelitis, or rubella were reported in 2020-2021. Conclusion: Restrictions placed to mitigate the effects of the COVID-19 pandemic were associated with significant reductions in other VPDs, which were sustained into 2021. Nevertheless, it is important that high levels of population vaccine coverage continue, to prevent a rebound increase in VPDs as restrictions are eased, and to maximise protection against VPDs for all Australians.

Impact of the SARS-CoV-2 pandemic on vaccine-preventable disease campaigns.

BACKGROUND: The COVID-19 pandemic has contributed to the widespread disruption of immunization services, including the postponement of mass vaccination campaigns. METHODS: In May 2020, the World Health Organization and partners started monitoring COVID-19-related disruptions to mass vaccination campaigns against cholera, measles, meningitis A, polio, tetanus-diphtheria, typhoid, and yellow fever through the Immunization Repository Campaign Delay Tracker. The authors reviewed the number and target population of reported preventive and outbreak response vaccination campaigns scheduled, postponed, canceled, and reinstated at 4 time points: May 2020, December 2020, May 2021, and December 2021. FINDINGS: Mass vaccination campaigns across all vaccines were disrupted heavily by COVID-19. In May 2020, 105 of 183 (57%) campaigns were postponed or canceled in 57 countries because of COVID-19, with an estimated 796 million postponed or missed vaccine doses. Campaign resumption was observed beginning in July 2020. In December 2021, 77 of 472 (16%) campaigns in 54 countries, mainly in the African Region, were still postponed or canceled because of COVID-19, with about 382 million postponed or missed vaccine doses. INTERPRETATION: There is likely a high risk of vaccine-preventable disease outbreaks across all regions because of an increased number of susceptible persons resulting from the large-scale mass vaccination campaign postponement caused by COVID-19.

Burden of vaccine-preventable diseases among at-risk adult populations in the US.

Life-course immunization holds significant benefit for population health by reducing the burden of vaccine-preventable diseases (VPD) through vaccinating individuals at different stages and circumstances in life. The study aimed to determine the epidemiologic, clinical, economic, and societal burden of VPDs among at-risk adult subpopulations in the United States. A systematic literature review was conducted for articles published between January 2010 and June 2020, which identified 72 publications. There was heterogeneity in available epidemiology data, with the prevalence of VPDs ranging from 1.1% to 68.7%. Where the disease burden was described, outcomes were typically worse among high-risk subpopulations than in the general population. Several VPDs, including herpes zoster, meningococcal, and pneumococcal infections were associated with increased costs. This review suggests that subpopulations may not frequently interact with the healthcare system, or their risk factors may not be recognized by healthcare providers, and therefore individuals may not be appropriately targeted for vaccination.

Admissions due to vaccine preventable diseases in a large paediatric intensive care unit in Greece over a 10-year period.

AIM: Childhood immunisation is an important preventive measure. However, care givers may delay routine immunisations or seek exemptions from state vaccine mandates. Vaccine refusal creates barriers on vaccine coverage and leads to morbidity and mortality. METHODS: Our study reviews morbidity and mortality from vaccine preventable diseases (VPDs) in a large paediatric intensive care unit in Greece over a 10-year period. RESULTS: During the study period, 73 cases of VPDs were recorded, corresponding to 3.5% of total paediatric intensive care unit admissions. Influenza was the most prevalent VPD, followed by pneumococcal disease, measles, pertussis and meningococcal disease. Most patients (83.3%) were unvaccinated for the admission's VPD. Outcome was unfavourable for 31.9% of the patients (17 children died, 6 developed chronic impairment). CONCLUSION: Absent or incomplete vaccination may result in serious morbidity and mortality from preventable diseases. Strengthening vaccination strategies are needed to improve individual protection as well as herd immunity.

Burden of vaccine-preventable diseases, trends in vaccine coverage and current challenges in the implementation of the expanded program on immunization: A situation analysis of Cameroon.

The discovery and development of vaccines remain one of the major successes of global health with millions of lives saved every year through routine vaccination. Although vaccines provide a safe and cost-effective solution to vaccine-preventable diseases (VPDs), VPDs are still a serious public health problem in most parts of the world, especially in sub-Saharan Africa (SSA) and Asia. In this review, we discuss the burden of VPDs and vaccine coverage several decades after the introduction of the Expanded Program on Immunization (EPI) in Cameroon. We also discuss how different factors affect the implementation of the EPI, highlighting context-specific factors such as the ongoing civil conflict in Cameroon, and the presence of other infectious diseases like COVID-19.