Heidi J Larson

London School of Hygiene and Tropical Medicine and Unversity of Washington (Seattle)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continued to mutate and spread in 2022 despite the introduction of safe, effective vaccines and medications. Vaccine hesitancy remains substantial, fueled in part by misinformation. Our third study of Coronavirus Disease 2019 (COVID-19) vaccine hesitancy among 23,000 respondents in 23 cou...

Background Little is known about how social media platforms can be used to increase COVID-19 vaccine intent. We aimed to investigate the effect of social media-based interventions on vaccine hesitancy in Japan. Methods We conducted a three-arm randomized controlled trial between 5 November 2021 and 9 January 2022. Japanese aged 20 or above who had...

The uptake of non-EPI vaccines, such as influenza and pneumonia vaccines, are very low in China compared to other countries. In China, immunization services are provided by dedicated vaccination service providers (VSPs), and their recommendation is the key to improve vaccine uptake. This study explores VSP recommendation practices for non-EPI vacci...

Digital approaches are increasingly common in clinical trial recruitment, retention, analysis, and dissemination. Community engagement processes have contributed to the successful implementation of clinical trials and are crucial in enhancing equity in trials. However, few studies focus on how digital approaches can be implemented to enhance commun...

Young children aged 6–59 months are recommended as one of the priority groups for seasonal influenza vaccination in China. This study assessed influenza vaccination coverage and the factors associated with vaccination uptake among children in three Chinese provinces. In September 2021, 2081 caregivers with children <5 years completed self-administe...

Background: COVID-19 vaccination has faced a range of challenges from supply-side barriers such as insufficient vaccine supply and negative information environment and demand-side barriers centring on public acceptance and confidence in vaccines. This study assessed global spatiotemporal trends in demand- and supply-side barriers to vaccine uptake...

During the COVID-19 pandemic, the emergence of the infodemic and vaccine hesitancy posed a significant challenge to adequate vaccine uptake. In response, conversational AI services such as chatbots have become an increasingly popular tool in the field of health service delivery and communication to increase individuals’ health literacy and vaccinat...

Background Polarized debates about Covid-19 vaccination and vaccine mandates for healthcare workers (HCWs) challenge Belgian HCWs ability to discuss Covid-19 vaccine sentiments with peers and patients. Although studies have identified drivers of HCWs vaccine hesitancy, they do not include effects of workplace interactions and have not addressed con...

BACKGROUND During the early 2020s use of conversational AI (chatbots) in healthcare expanded significantly, especially in the context of increased burdens on health systems and restrictions on in-person consultations with healthcare providers during the COVID-19 pandemic. One emerging use case for conversational AI is related to communicating infor...

Background Health care professionals are widely considered to be the most trusted source of information on vaccine-related topics. However, several are reporting their own hesitancy around certain vaccines, influencing their intention to vaccinate themselves as well as influencing their recommendations to their patients and target population. Meth...

With approval of more COVID-19 vaccines for children, vaccine attributes may influence parental acceptance and choices. We aimed to assess effects of vaccine attributes and information on herd immunity on childhood COVID-19 vaccine acceptance. A survey experiment was conducted with caregivers of children aged 6 months to 11 years old and health car...

Background China has low seasonal influenza vaccination rates among priority populations. In this study, we aimed to evaluate a pay-it-forward strategy to increase influenza vaccine uptake in rural, suburban, and urban settings in China. Methods We performed a quasi-experimental pragmatic trial to examine the effectiveness of a pay-it-forward inte...

Introduction: Migration can be linked to the transmission of vaccine-preventable diseases. Hence, monitoring migrants' vaccination-related concerns can inform needed interventions to support vaccine acceptance. Areas covered: Along with Google and Google Scholar, we searched 13 bibliographic databases between January 1, 2000 and October 10, 2020...

In 2019, the World Health Organization (WHO) named “Vaccine Hesitancy” one of the top 10 threats to global health. Shortly afterward, the COVID‐19 pandemic emerged as the world's predominant health concern. COVID‐19 vaccines of several types have been developed, tested, and partially deployed with remarkable speed; vaccines are now the primary cont...

Health-care professionals (HCPs) have a fundamental role in vaccination, their own beliefs and attitudes affecting both their uptake and recommendation of vaccines. This literature review (n = 89) summarises evidence on HCPs' perceptions of the risks and benefits of vaccination, trust, and perceptions of mandatory vaccination in Europe. HCPs across...

The COVID-19 ‘infodemic’ continues to undermine trust in vaccination efforts aiming to bring an end to the pandemic. However, the challenge of vaccine hesitancy is not only a problem of the information ecosystem and it often has little to do with the vaccines themselves. In this Perspective, we argue that the epidemiological and social crises broug...

Human Papillomavirus (HPV) vaccination is one of the most publicly mistrusted vaccines in Europe, with countries such as France struggling with low vaccine uptake due to parental questioning of vaccine risks and benefits. However, limited evidence exists on adolescent girls' perceptions of the risks and benefits of HPV vaccination. The aim of this...

Developing and implementing new immunization policies in response to shifting epidemiology is a critical public health component. We adopted a mixed-methods approach (via narrative literature review [101 articles] and 9 semi-structured interviews) to evaluate policy development in response to shifting measles epidemiology in six European countries...

Delayed acceptance or refusal of COVID-19 vaccines may increase and prolong the threat to global public health and the economy. Identifying behavioural determinants is considered a critical step in explaining and addressing the barriers of vaccine refusal. This study aimed to identify the behavioural determinants of COVID-19-vaccine acceptance and...

The success of vaccination programmes relies on high uptake and acceptance of vaccines, which is in part influenced by public trust in vaccines, providers, policy-makers and information. France is one of the countries in the world with the lowest confidence in vaccination, with parents expressing particular concerns about the human papillomavirus (...

Healthcare workers are a priority target population in current COVID-19 vaccination strategies because of their increased workplace exposure and contacts with potentially at-risk patients. In some European countries such as Belgium, Greece, and France, COVID-19 vaccination is now required for this group. However, studies show that a varying but oft...

Background Understanding how people’s emotions influence their health decisions and behaviours at a population level is fundamental to designing effective communication strategies and public health interventions for infectious disease outbreaks. This review identifies relevant research to assess the role of emotional determinants and their impact o...

China has low seasonal influenza vaccination rates among children and older adults. This quasi-experimental pragmatic trial examined the effectiveness of a pay-it-forward intervention on influenza vaccination compared to standard of care (user-paid vaccination) and free vaccination strategies among children and older people in China (ChiCTR20000400...

Vaccine-hesitant individuals are a heterogeneous group that are indecisive in varying degrees – more of a spectrum – about specific vaccines or vaccination in general. Vaccine hesitancy is complex, varying by vaccine, time, context, geographic region, and sub-population. There is an “infodemic” that needs to be fought alongside the pandemic as expo...

Background China has low seasonal influenza vaccination rates among children and older adults. This quasi-experimental pragmatic trial examined the effectiveness of a pay-it-forward intervention on influenza vaccine uptake among children and older adults compared to standard of care (user-paid vaccination) and free vaccination strategies in China....

Background Children account for a substantial proportion of cases and deaths from Ebola virus disease. We aimed to assess the safety and immunogenicity of a two-dose heterologous vaccine regimen, comprising the adenovirus type 26 vector-based vaccine encoding the Ebola virus glycoprotein (Ad26.ZEBOV) and the modified vaccinia Ankara vector-based va...

Background The Ebola epidemics in west Africa and the Democratic Republic of the Congo highlight an urgent need for safe and effective vaccines to prevent Ebola virus disease. We aimed to assess the safety and long-term immunogenicity of a two-dose heterologous vaccine regimen, comprising the adenovirus type 26 vector-based vaccine encoding the Ebo...

Peter Figueroa and co-authors advocate for equity in the worldwide provision of COVID-19 vaccines.

Background As the world begins the rollout of multiple COVID-19 vaccines, pandemic exit strategies hinge on widespread acceptance of these vaccines. In this study, we perform a large-scale global exploratory study to examine the levels of COVID-19 vaccine acceptance and explore sociodemographic determinants of acceptance. Methods Between October 3...

Objective: This trial aimed to determine if return rates of consent forms for vaccination could be improved when Vaxcards were offered as an incentive to school children. Setting: Nineteen schools in South East Melbourne participated. Interventions: Students in the experimental arm received a pack of Vaxcards when they returned their governmen...

Mothers are often responsible for vaccination decisions in the household. However, their confidence in certain vaccines such as Human Papillomavirus (HPV) vaccines is eroding in some countries. France is one of the countries with the lowest HPV vaccine uptake in Europe, with parents delaying or refusing the vaccine for their adolescent daughters du...

A Lancet Commission for COVID-19 task force is shaping recommendations to achieve vaccine and therapeutics access, justice, and equity. This includes ensuring safety and effectiveness harmonized through robust systems of global pharmacovigilance and surveillance. Global production requires expanding support for development, manufacture, testing, an...

The expansion in the scope, scale, and sources of data on the wider social determinants of health (SDH) in the last decades could bridge gaps in information available for decision-making. However, challenges remain in making data widely available, accessible, and useful towards improving population health. While traditional, government-supported da...

Background The UK Government is considering the introduction of vaccine passports for domestic use and to facilitate international travel for UK residents. Although vaccine incentivisation has been cited as a motivating factor for vaccine passports, it is unclear whether vaccine passports are likely to increase inclination to accept a COVID-19 vacc...

Background: Massive community-wide testing has become the cornerstone of management strategies for the COVID-19 pandemic. Objective: This study was a comparative analysis between the United Kingdom and China, which aimed to assess public attitudes and uptake regarding COVID-19 testing, with a focus on factors of COVID-19 testing hesitancy, inclu...

Background While vaccines ensure individual protection against COVID-19 infection, delay in receipt or refusal of vaccines will have both individual and community impacts. The behavioral factors of vaccine hesitancy or refusal are a crucial dimension that need to be understood in order to design appropriate interventions. The aim of this study was...

Depression accounts for a large share of the global disease burden, with an estimated 264 million people globally suffering from depression. Despite being one of the most common kinds of mental health (MH) disorders, much about depression remains unknown. There are limited data about depression, in terms of its occurrence, distribution, and wider s...

By refusing or delaying vaccination, vaccine hesitant individuals and communities undermine the prevention, and ultimately, elimination of communicable diseases against which safe and effective vaccines are available. We reviewed recent evidence of vaccine hesitancy within migrant communities in the context of increased human mobility and widesprea...

Despite the important benefits of maternal vaccination for pregnant women and newborns, vaccination uptake is low in many European countries. Differences in vaccination policies and recommendations, as well as concerns about vaccine safety can partly explain inadequate coverage rates and women’s hesitancy to get vaccinated during pregnancy. This st...

Objectives To identify pregnant women’s views and attitudes towards maternal immunisation in Panama based on in-depth interviews and focus groups. Setting Two main urban centres in Panama (San Miguelito and Panama City). Participants Fifty-six pregnant women from Panama City (n=29) and San Miguelito (n=27). Methods In-depth interviews and focus...

Background Vaccination coverage remains suboptimal in many parts of the world, especially in low-and middle-income countries (LMICs), including South Africa. Vaccine hesitancy, a recognized factor contributing to low vaccination uptake in many parts of the world, is suspect in the suboptimal vaccination coverage level in South Africa, particularly...

Maternal immunization is key to protecting maternal and newborn health. We interviewed pregnant women in Brazil to identify barriers to and enablers of maternal immunization in the country. In-depth interviews and focus groups were conducted in Brazil with 60 pregnant women from São Paulo and Rio de Janeiro at different stages of their pregnancies....

Vaccine hesitancy – defined by the World Health Organization (WHO) as a “delay in acceptance or refusal of vaccines despite availability of vaccination services” is not a recent phenomenon. Historical records indicate that vaccine hesitancy existed by the 18th century in Europe and even resulted in violent riots. The drivers of vaccine hesitancy ha...

Background Maternal vaccination is key to decreasing maternal and infant mortality globally. Yet perceptions about maternal vaccines and immunization among pregnant women are often understudied, particularly in low- and middle- income countries. This qualitative study explored trust, views, and attitudes towards maternal immunization among pregnant...

Background: Multiple COVID-19 vaccines have now been licensed for human use, with other candidate vaccines in different stages of development. Effective and safe vaccines against COVID-19 are essential to achieve global control of the pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2), but multiple factors, including vaccine sup...

Background Vaccination during pregnancy can protect pregnant women and their babies from infectious diseases. Tetanus vaccine, also known as tetanus toxoid, is the only vaccine given to pregnant women in The Gambia and Senegal, where it is given by antenatal care providers as part of the Expanded Programme on Immunization. A qualitative study was u...

Vaccine confidence reflects social, individual, and political factors indicating confidence in vaccines and associated health systems. In Japan, the government ceased proactive recommendation of the human papillomavirus (HPV) vaccine in June 2013, only several months after the recommendation had begun. Seven years later, as of October 2020, the sus...

Background: Four vaccines against the novel coronavirus 2019 disease (COVID-19) caused by the severe acute respiratory coronavirus 2 (SARS-CoV-2) have currently been approved for use in the United Kingdom. As of 30 April 2021, over 34 million adults have received at least one dose of a COVID-19 vaccine. The UK Government is considering the introduc...

Maternal vaccination is an important strategy to reduce maternal and newborn mortality and morbidity. Yet, vaccination uptake is suboptimal in many countries, including France. This mixed-method study aimed to identify factors influencing maternal vaccination, exploring pregnant women’s perceptions, confidence, and decision-making processes in Fran...

Vaccine hesitancy is prevalent in all demographic groups and settings; however, it remains vastly understudied in low-income and middle-income regions. Successful strategies to address hesitancy require an understanding of regional, cultural, and economic factors, and tailored training of health-care professionals. Vaccine confidence crises should...

In the context of emerging COVID-19 virus variants, trends of vaccine nationalism, and multiple vaccine supply challenges, COVID-19 vaccine related uncertainties and challenges continue. Additionally, confidence in new COVID-19 vaccines is highly variable, with minority communities generally less trusting of not only the new vaccines, but also thos...

Undertaking recruitment for research in schools is an effective way to recruit young people for research participation but it is not without its challenges. Gaining access and coordinating many levels of different organisations and stakeholders whose cooperation and approval are crucial all add time and sometimes logistical challenges for the resea...

Background: This review aims to (i) identify and critique existing methods of community engagement for outbreak preparedness and response in high-income settings, and (ii) understand community members' experiences of community engagement, and their views and concerns towards pandemic planning/response. Methods: Following the PRISMA guidelines, a...

Among the realm of highly varied vaccine perceptions and concerns expressed by publics around the world, vaccine safety is the most frequently cited. While many of the safety questions raised have substantial evidence to address the concerns, vaccines do have small risks, and need vigilant and responsive systems to address them. With more and more...

Background While vaccines ensure individual protection against COVID-19 infection, delay in receipt or refusal of vaccines will have both individual and community impacts. The behavioral factors of vaccine hesitancy or refusal are a crucial dimension that need understanding to implicate appropriate interventions. The aim of this study was to assess...

Background: While a vaccine is the only clinical preventive measure to control the infection and mortality caused by SARS-CoV-2 (COVID-19), delayed acceptance or refusal of COVID-19 vaccines may increase and prolong the threat to global public health and the economy. Identifying behavioural determinants is considered a critical step in explaining a...

Background: With growing conversations online and less than desired maternal vaccination uptake rates, these conversations could provide useful insight to inform future interventions. Automated processes for this type of analysis, such as natural language processing (NLP), have faced challenges extracting complex stances, like attitudes toward vacc...

Background: With growing conversations online and less than desired maternal vaccination uptake rates, these conversations could provide useful insight to inform future interventions. Automated processes for this type of analysis, such as natural language processing (NLP), have faced challenges extracting complex stances, like attitudes toward vacc...

Last week, the European Medicines Agency declared the AstraZeneca COVID-19 vaccine safe and effective, after several European Union member states had suspended its use because of blood clot concerns. Will the public trust this message? This week's news could help—a U.S. phase 3 clinical trial of the vaccine shows promising efficacy in preventing sy...

Widespread acceptance of a vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will be the next major step in fighting the coronavirus disease 2019 (COVID-19) pandemic, but achieving high uptake will be a challenge and may be impeded by online misinformation. To inform successful vaccination campaigns, we conducted a randomized...

Access to vaccination information could influence public attitudes towards vaccination. This study investigated the number and types of vaccination-related information sources, and estimated their associations with vaccine confidence and hesitancy in China. In January 2019, we conducted a cross-sectional survey in China, and 2122 caregivers with ch...

A Correction to this paper has been published: https://doi.org/10.1038/s41562-021-01088-7.