Impacts of free vaccination policy and associated factors on influenza vaccination behavior of the elderly in China: A quasi-experimental study

Vaccination Promotion Strategies in the Elderly: Systematic Review and Meta-Analysis

Background: The World Health Organization estimates that currently available vaccines prevent 2 to 3 million deaths worldwide each year. Preventing infectious diseases is an important public health priority to ensure healthy ageing and improve quality of life. This study's aim is to identify the best strategies to increase vaccination coverage in the elderly. Methods: A systematic review and meta-analysis were carried out, including a bibliographic search in the PubMed and Scopus databases. Studies in older people (60 years or older) on any type of intervention aimed at increasing vaccination coverage were included. The effect of the intervention was measured using the odds ratio (OR). Results: After applying the selection criteria, 20 studies were identified: 17 on influenza vaccines and 3 on other vaccines. Educational strategies obtained an OR = 1.63 (95% CI: 1.22-2.19, I2 = 0.59). Medical counselling obtained an OR = 3.13 (95% CI: 0.60-16.37, I2 = 0.95). Writing strategies obtained an OR = 1.14 (95% CI: 0.99-1.32, I2 = 0.93). Few studies reported the effect of free vaccination. Conclusions: The educational strategies proved to be more effective than the others in this study. Free vaccination and age may have important roles. Further studies are needed as research in this area remains limited.

Vaccine uptake, associated factors and reasons for vaccination status among the South African elderly; findings and next steps

OBJECTIVES

The elderly are particularly prone to complications from a number of vaccine-preventable diseases. However, there are limited data on vaccine uptake for this vulnerable population in South Africa. Consequently, this study investigated influenza, pneumococcal and shingles vaccine uptake among elderly people in South Africa; reasons for their vaccination status; and factors associated with their uptake.

METHODS

Cross-sectional study using an interviewer-administered questionnaire to survey 985 consenting adults aged ≥65 years in 2018. Participants were recruited from across South Africa. Bivariate analysis was used to identify socio-demographic variables associated with vaccine uptake, with multivariate logistic regression analysis used to identify key factors associated with vaccine uptake.

RESULTS

Influenza vaccine uptake was 32.3% (318/985), with uptake highest in those aged 85-90 years. Pneumococcal and shingles vaccine uptake was 3.8% (37/985) and 0.4% (4/985) respectively, being highest among those aged >90 years. The strongest statistically significant predictors for influenza vaccination were previous influenza vaccination (OR: 8.42 [5.61-12.64]); identifying as 'Coloured' (OR: 8.39 [3.98-17.69]); and residing in Gauteng Province (OR: 5.44 [3.30-9.02]). The strongest statistically significant predictors of receiving pneumococcal vaccination included receiving influenza vaccination (OR = 10.67 [3.27-37.83]); residing in the Western Cape Province (OR: 7.34 [1.49-36.22]); identifying as 'Indian' (OR: 5.85 [2.53-13.55]); and having a university education (OR: 5.56 [1.25-24.77]). Statistically significant barriers to receiving influenza vaccination included following the Traditional African religion (OR: 0.08 [0.01-0.62]) and residing in Limpopo Province (OR: 0.16 [0.04-0.71]). The main reasons for non-vaccination were considering influenza as a mild illness (36.6%; 242/661), and lack of knowledge about the pneumococcal (93.4%; 886/948) and shingles (95.2%; 934/981) vaccines.

CONCLUSION

Vaccine uptake for all vaccines was sub-optimal, with multiple non-modifiable factors predicting vaccine uptake. These pre-COVID-19 data provide a baseline for measuring the effectiveness of future interventions to increase vaccine uptake and safeguard the health of the elderly.

Promoting Influenza Vaccination Uptake Among Chinese Older Adults Based on Information-Motivation-Behavioral Skills Model and Conditional Economic Incentive: Protocol for Randomized Controlled Trial

Background: Influenza poses a substantial health burden, especially among older adults in China. While vaccination is one of the most effective preventions, influenza vaccine uptake rates among Chinese older adults remain low. This study examines the individual and combined effects of behavioral interventions based on the Information-Motivation-Behavioral Skills (IMB) model and economic incentives in promoting influenza vaccine uptake among older adults living in China. Methods: The study will recruit 640 older adults living in eight communities that have not been covered by the free influenza vaccination policy. These eight communities (as clusters), stratified by urban and rural, will be randomized to four parallel arms, including a usual care arm, an IMB-based behavioral intervention arm, a conditional economic incentive arm, and a combined behavioral-economic arm. The interventions will start from the beginning of the flu season and last for about one month. Specifically, the IMB-based behavioral intervention encompasses health education brochures, healthcare provider-led lectures, interactive quizzes, and personalized consultations. The exact number of economic incentives is conditional on the timing of vaccination (a higher amount for early immunization) and the number of people within a household to be vaccinated at the same appointment (a higher amount for more people). The primary outcome is the influenza vaccination rate. Data will be gathered through vaccination records and questionnaires covering IMB-based vaccination cognitions. Mixed-effects models will be used to analyze the outcome of vaccination rate, reporting difference-in-differences estimates with 95% confidence intervals. Conclusions: The results of this study have the potential to inform influenza vaccination program scaleup among older adults who are not yet covered by the free influenza vaccination policy. Ethics and dissemination: Ethics approval has been granted by the ethics commission of Peking University Health Science Centre (IRB00001052-24090). Participants will be required to sign a written consent form. Findings will be reported in conferences and peer-reviewed publications in accordance with the recommendations of the Consolidated Standards of Reporting Trials. Registration number: This study was registered at the Chinese Clinical Trial Registry (ChiCTR2400090229).

Association Between Sociodemographic Factors and Vaccine Acceptance for Influenza and SARS-CoV-2 in South Korea: Nationwide Cross-Sectional Study

Background

The imperative arises to study the impact of socioeconomic factors on the acceptance of SARS-CoV-2 and influenza vaccines amid changes in immunization policies during the COVID-19 pandemic.

Objective

To enhance targeted public health strategies and improve age-specific policies based on identified risk factors, this study investigated the associations between sociodemographic factors and vaccination behaviors during the COVID-19 pandemic, with emphasis on age-specific vaccine cost policies.

Methods

This study analyzed data from the Korean Community Health Survey 2019-2022 with 507,964 participants to investigate the impact of age-specific policies on vaccination behaviors during the pandemic period. Cohorts aged 19-64 years and 65 years or older were stratified based on age (years), sociodemographic factors, and health indicators. The cohorts were investigated to assess the influence of relevant risk factors on vaccine acceptance under the pandemic by using weighted odds ratio and ratio of odds ratio (ROR).

Results

Among 507,964 participants, the acceptance of the SARS-CoV-2 vaccine (COVID-19 vaccine) was higher among individuals with factors possibly indicating higher socioeconomic status, such as higher education level (age 19-64 years: ROR 1.34; 95% CI 1.27-1.40 and age ≥65 years: ROR 1.19; 95% CI 1.01-1.41) and higher income (age 19-64 years: ROR 1.67; 95% CI 1.58-1.76 and age ≥65 years: ROR 1.21; 95% CI 1.06-1.38) for both age cohorts compared to influenza vaccine acceptance before the pandemic. In the context of influenza vaccination during the pandemic, the older cohort exhibited vaccine hesitancy associated with health care mobility factors such as lower general health status (ROR 0.89; 95% CI 0.81-0.97).

Conclusions

SARS-CoV-2 vaccination strategies should focus on reducing hesitancy among individuals with lower social participation. To improve influenza vaccine acceptance during the pandemic, strategies for the younger cohort should focus on individuals with lower social participation, while efforts for the older cohort should prioritize individuals with limited access to health care services.

Acceptance of Rubella-Containing Vaccine and Factors Associated with Acceptance among Women of Reproductive Age in China: A Cross-Sectional Study

Objectives: To investigate the acceptance and factors influencing acceptance of rubella-containing vaccine (RCV) among women of reproductive age in Guangdong, Henan, Hubei, Liaoning, Shanxi, Sichuan and Zhejiang provinces of China. Methods: Using a stratified sampling method, we selected one urban and one rural community health services center in each of two cities in seven provinces. From these centers, we recruited women 15-49 years of age to complete a questionnaire on their willingness to receive RCV and factors influencing willingness. The survey instrument was adapted from the behavioral and social drivers (BeSD) of vaccination survey tool developed by the World Health Organization. Results: Among 1286 participants, 981 (76.3%) were willing to receive RCV. Awareness of rubella ranged from 12.4% to 70.6%. Willingness to receive RCV differed significantly by region, occupation, vaccination history, and awareness. All latent variables of the structural equation model (SEM) were positively correlated with willingness, and all standardized paths were statistically significant (p < 0.001). Thinking and Feeling had direct positive effects on Social Processes (β = 0.789) and Practical Issues (β = 0.542), thereby indirectly affecting motivation. Conclusions: Women of reproductive age had high willingness to receive the rubella vaccination, but their general awareness of rubella was relatively low. It is necessary to strengthen the health education of women of reproductive age regarding rubella to improve RCV coverage.

Combating the Co-Circulation of SARS-CoV-2 and Seasonal Influenza: Identifying Multi-Dimensional Factors Associated with the Uptake of Seasonal Influenza Vaccine among a Chinese National Sample

INTRODUCTION

The co-circulation of COVID-19 and seasonal influenza highlighted the importance of promoting influenza vaccination. However, the influenza vaccination rate among the Chinese population is low and requires further promotion. This study examined multi-dimensional factors, such as knowledge of seasonal influenza, health perceptions, cues to action, patient-provider relationships, and COVID-19 pandemic-related factors, in relation to the uptake of the seasonal influenza vaccine (SIV) among the Chinese population.

METHODS

A cross-sectional, self-administered online survey using a quota sampling method was conducted among Chinese adults 18 years and older between June and August 2022. Multivariate logistic regression was performed to explore factors associated with the 2021 SIV behavior.

RESULTS

A total of 3161 individuals from different regions of China were included in this study. The multivariate logistic regression demonstrated that perceived severity of influenza, perceived barriers to taking SIV, cues to action, a stable relationship with providers, worry about contracting COVID-19 in immunization settings, non-pharmaceutical interventions (NPIs), and awareness of the influenza vaccine in protecting against COVID-19 were significantly associated with the SIV uptake.

CONCLUSIONS

This study examined multi-dimensional factors that may influence SIV uptake. Health promotion programs should incorporate multi-dimensional factors, including personal and environmental factors, related to SIV promotion during the co-circulation period.

Neutralizing antibody responses against contemporary and future influenza A(H3N2) viruses in paradoxical clades elicited by repeated and single vaccinations

As one of the most effective measures to prevent seasonal influenza viruses, annual influenza vaccination is globally recommended. Nevertheless, evidence regarding the impact of repeated vaccination to contemporary and future influenza has been inconclusive. A total of 100 subjects singly or repeatedly immunized with influenza vaccines including 3C.2a1 or 3C.3a1 A(H3N2) during 2018-2019 and 2019-2020 influenza season were recruited. We investigated neutralization antibody by microneutralization assay using four antigenically distinct A(H3N2) viruses circulating from 2018 to 2023, and tracked the dynamics of B cell receptor (BCR) repertoire for consecutive vaccinations. We found that vaccination elicited cross-reactive antibody responses against future emerging strains. Broader neutralizing antibodies to A(H3N2) viruses and more diverse BCR repertoires were observed in the repeated vaccination. Meanwhile, a higher frequency of BCR sequences shared among the repeated-vaccinated individuals with consistently boosting antibody response was found than those with a reduced antibody response. Our findings suggest that repeated seasonal vaccination could broaden the breadth of antibody responses, which may improve vaccine protection against future emerging viruses.

A review of factors influencing vaccination policies and programs for older adults globally

Policies and programs to increase vaccine coverage rates among adults 50 years of age or older are limited and vaccine uptake is often suboptimal. Our review evaluated evidence on the effectiveness and success of adult-targeted vaccination interventions and identified literature gaps. Literature was retrieved (2021) from PubMed, Embase, and Google Scholar databases. Outcomes assessed included data on an intervention's effectiveness and impact on vaccine uptake. Interventions were characterized thematically: affordability (n = 9), awareness (n = 25), and vaccination access (n = 6); and included influenza, pneumococcal, tetanus-containing, and herpes zoster vaccines. Interactive interventions directed toward patients, including provider-led educational initiatives and provider recommendations showed more positive associations than less interactive interventions, such as posters and reminder-recall letters. Provider interventions, including awareness campaigns, incentives, affordability efforts, or vaccination site expansion generally showed positive associations. Combining interventions was found to be successful across several studies. Barriers and interventions varied for population subgroups, therefore, tailoring programs is critical.

The association between influenza vaccination and the perception of COVID-19 as well as COVID-19 vaccination behavior among community residents in Anhui province, China

Influenza is a significant public health threat associated with high morbidity and mortality globally. This study investigated the influenza vaccination rate (IVR) among community residents in Anhui province, China, and explored the association between participants' influenza vaccination and their key sociodemographic characteristics, perception of COVID-19 as well as COVID-19 vaccination behavior. We found that the IVR among respondents in Anhui province was 27.85% in 2020. Regression analyses revealed that males (OR = 1.41, 95% CI: 1.01 ~ 1.96), residents with above middle school education (OR = 1.88, 95% CI: 1.04 ~ 3.39), considered themselves likely to be infected with COVID-19 (OR = 1.53, 95% CI: 1.04 ~ 2.24), had received the COVID-19 vaccine (OR = 9.85, 95% CI: 3.49 ~ 27.78), did not plan to receive COVID-19 vaccine in the future (OR = 1.70, 95% CI: 1.17 ~ 2.47), and had no adverse reactions after COVID-19 vaccination (OR = 1.54, 95% CI: 1.04 ~ 2.27) were associated with a higher IVR. The acceptance of influenza vaccination was mainly associated with respondents' gender, education, perception of COVID-19, history of COVID-19 vaccination in city and countryside community residents in Anhui province.

Reasons for Being "Zero-Dose and Under-Vaccinated" among Children Aged 12-23 Months in the Democratic Republic of the Congo

(1) Introduction: The Democratic Republic of the Congo (DRC) has one of the largest cohorts of un- and under-vaccinated children worldwide. This study aimed to identify and compare the main reasons for there being zero-dose (ZD) or under-vaccinated children in the DRC. (2) Methods: This is a secondary analysis derived from a province-level vaccination coverage survey conducted between November 2021 and February 2022; this survey included questions about the reasons for not receiving one or more vaccines. A zero-dose child (ZD) was a person aged 12-23 months not having received any pentavalent vaccine (diphtheria-tetanus-pertussis-Hemophilus influenzae type b (Hib)-Hepatitis B) as per card or caregiver recall and an under-vaccinated child was one who had not received the third dose of the pentavalent vaccine. The proportions of the reasons for non-vaccination were first presented using the WHO-endorsed behavioral and social drivers for vaccination (BeSD) conceptual framework and then compared across the groups of ZD and under-vaccinated children using the Rao-Scott chi-square test; analyses were conducted at province and national level, and accounting for the sample approach. (3) Results: Of the 51,054 children aged 12-23 m in the survey sample, 19,676 ZD and under-vaccinated children were included in the study. For the ZD children, reasons related to people's thinking and feelings were cited as 64.03% and those related to social reasons as 31.13%; both proportions were higher than for under-vaccinated children (44.7% and 26.2%, respectively, p < 0.001). Regarding intentions to vaccinate their children, 82.15% of the parents/guardians of the ZD children said they wanted their children to receive "none" of the recommended vaccines, which was significantly higher than for the under-vaccinated children. In contrast, "practical issues" were cited for 35.60% of the ZD children, compared to 55.60% for the under-vaccinated children (p < 0.001). The distribution of reasons varied between provinces, e.g., 12 of the 26 provinces had a proportion of reasons for the ZD children relating to practical issues that was higher than the national level. (4) Conclusions: reasons provided for non-vaccination among the ZD children in the DRC were largely related to lack of parental/guardian motivation to have their children vaccinated, while reasons among under-vaccinated children were mostly related to practical issues. These results can help inform decision-makers to direct vaccination interventions.

Estimation of vaccination coverage and associated factors in older Mexican adults

National vaccination programmes recommend the influenza vaccine for older adults, but this population group has the greatest morbidity and mortality from other preventable vaccine diseases. The aim of this article is to estimate the vaccine coverage in adults aged 65 years and older and to analyse the factors that could increase or decrease vaccination uptake probability for the three listed vaccines in the national vaccination programme (influenza, tetanus and diphtheria, and pneumococcus) and the full scheme in Mexico. We conducted an analytical cross-sectional study with 2012, 2018, and 2021 rounds from the National Health and Nutrition Survey, in which we calculated the vaccine coverage estimations and performed multivariable logistic regression models to analyse the factors related to vaccine uptake. Tetanus and diphtheria vaccines had the greatest coverage estimation in all years (59-71%), whereas the pneumococcus vaccine had the lowest (32-53%). Full scheme vaccine coverage decreased from 37.80% to 24.77% in 2012 and 2021, respectively. The National Health Card property, morbidity, being a beneficiary of any health system institution, and use of preventive services increased the probability of vaccine uptake. In conclusion, vaccine coverage in older Mexican adults decreased over time, and the Mexican health system plays a strategic role in immunisation.

Addressing Unmet Needs in Vaccination for Older Adults in the Asia Pacific: Insights from the COVID-19 Pandemic

The impact of vaccinating the older population against vaccine-preventable diseases in terms of health, social and economic benefits has been increasingly recognised. However, there is a gap in the utilisation of vaccines worldwide. The population is ageing at an unprecedented pace in the Asia-Pacific (APAC) region, with the number of persons older than 65 years set to double by 2050 to around 1.3 billion. More than 18% of the population in Japan, Hong Kong, and China is over the age of 65 years. This highlights the importance of prioritising resources to address societal obligations toward the needs of the ageing generation. This review provides an overview of the challenges to adult vaccination in APAC, drivers to increase vaccination coverage, vaccination insights gained through the COVID-19 pandemic, and potential measures to increase the uptake of adult vaccines in the region.

"Zero Dose" Children in the Democratic Republic of the Congo: How Many and Who Are They?

(1) Background: The Democratic Republic of the Congo (DRC) is one of the countries with the highest number of never vaccinated or "zero-dose" (ZD) children in the world. This study was conducted to examine the proportion of ZD children and associated factors in the DRC. (2) Methods: Child and household data from a provincial-level vaccination coverage survey conducted between November 2021-February 2021 and 2022 were used. ZD was defined as a child aged 12 to 23 months who had not received any dose of pentavalent (diphtheria-tetanus-pertussis-Haemophilus influenzae type b (Hib)-Hepatitis B) vaccine (by card or recall). The proportion of ZD children was calculated and associated factors were explored using logistic regression, taking into account the complex sampling approach. (3) Results: The study included 51,054 children. The proportion of ZD children was 19.1% (95%CI: 19.0-19.2%); ZD ranged from 62.4% in Tshopo to 2.4% in Haut Lomami. After adjustment, being ZD was associated with low level of maternal education and having a young mother/guardian (aged ≤ 19 years); religious affiliation (willful failure to disclose religious affiliation as the highest associated factor compared to being Catholic, followed by Muslims, revival/independent church, Kimbanguist, Protestant); proxies for wealth such as not having a telephone or a radio; having to pay for a vaccination card or for another immunization-related service; not being able to name any vaccine-preventable disease. A child's lack of civil registration was also associated with being ZD. (4) Conclusions: In 2021, one in five children aged 12-23 months in DRC had never been vaccinated. The factors associated with being a ZD child suggest inequalities in vaccination that must be further explored to better target appropriate interventions.

Can primary care physician recommendation improve influenza vaccine uptake among older adults? A community health centre-based experimental study in China

BACKGROUND

To promote influenza vaccination coverage, a Chinese megacity, Shenzhen provides free influenza vaccination to its residents aged 60 years and above through community health centres (CHCs) since October 2016. A community health centre-based experiment was conducted by asking primary care physicians (PCPs) working in the intervention health centres to proactively recommend influenza vaccination to their patients aged 60 and above during their patients' visits.

METHODS

This study used an experimental design and a survey design. The experimental design evaluated the effect of PCP recommendation on influenza vaccination. A total of 24 CHCs were randomly selected as the intervention (involving 3814 participants) and control (3072 participants) group evenly. The intervention study period was during the 2017-2018 flu season. The 2016-2017 flu season was considered as the baseline comparison. The survey design examined changes in knowledge, attitude, and practice of influenza vaccination among older participants before and after the free influenza vaccination implementation. We randomly invited 1200 participants aged 60 and above during their visits to CHCs in October 2016 and followed them up until October 2017; among them, 958 participants completed the follow-up survey using the same questionnaire.

RESULTS

In the 2017-2018 flu season, 1,100 more patients got vaccinated in the intervention group under PCP recommendation compared with the 2016-2017 flu season. Among the 958 older adults in the post-implementation period, 77.5% had heard about the influenza vaccine, which was 24.7% higher than in the pre-implementation period; 84.8% of participants were aware where to take influenza vaccines, with the most improvement of 37.2% among all knowledge related questions; 62.5% of them agreed that patients with chronic diseases should have influenza vaccine, which was 19.1% higher than those being surveyed before the implementation period. About 83.6% of participants agreed older adults should have influenza vaccine, but there were still 58.4% who considered themselves too healthy to get vaccinated.

CONCLUSION

PCP recommendation improved influenza vaccine uptake and knowledge, attitude, and practice levels regarding influenza vaccination among older adults. More health policies and health education should be made to raise vaccination willingness and improve vaccination coverage among older adults.

Repeated influenza vaccination induces similar immune protection as first-time vaccination but with differing immune responses

BACKGROUND

Recent seasonal epidemics of influenza have been caused by human influenza A viruses of the H1N1 and H3N2 subtypes and influenza B viruses. Annual vaccination is recommended to prevent infection; however, how annual influenza vaccination influences vaccine effectiveness is largely unknown.

METHODS

To investigate the impact of repeated vaccination on immune and protective effect, we performed a prospective seroepidemiologic study. Participants with or without prior vaccination (2018-2019) were enrolled during the 2019-2020 influenza season. Inactivated quadrivalent influenza vaccine (IIV4) was administered through the intramuscular route, and venous blood samples were collected regularly to test hemagglutination inhibition (HAI) titers.

RESULTS

The geometric mean titers and proportion with titers ≥40 against the influenza vaccine components peaked at 30 days post-vaccination. At Day 30, the geometric mean titer and proportion with titers ≥40 in participants who had been previously vaccinated were higher for H3N2 but similar for both B lineages (Victoria and Yamagata) as compared with participants vaccinated for the first time. As for H1N1, the geometric mean titer was lower in repeated vaccinated participants, but the proportion with titers ≥40 was consistent in both groups.

CONCLUSIONS

Repeated vaccination provides similar or enhanced protection as compared with single vaccination in first-time vaccinees.

Effectiveness of a pay-it-forward intervention compared with user-paid vaccination to improve influenza vaccine uptake and community engagement among children and older adults in China: a quasi-experimental pragmatic trial

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 intervention (a free influenza vaccine and an opportunity to donate financially to support vaccination of other individuals) to increase influenza vaccine uptake compared with standard-of-care user-paid vaccination among children (aged between 6 months and 8 years) and older people (≥60 years) in China. Recruitment took place in the standard-of-care group until the expected sample size was reached and then in the pay-it-forward group in primary care clinics from a rural site (Yangshan), a suburban site (Zengcheng), and an urban site (Tianhe). Participants were introduced to the influenza vaccine by project staff using a pamphlet about influenza vaccination and were either asked to pay out-of-pocket at the standard market price (US$8·5-23·2; standard-of-care group) or to donate any amount anonymously (pay-it-forward group). Participants had to be eligible to receive an influenza vaccine and to have not received an influenza vaccine in the past year. The primary outcome was vaccine uptake. Secondary outcomes were vaccine confidence and costs (from the health-care provider perspective). Regression methods compared influenza vaccine uptake and vaccine confidence between the two groups. This trial is registered with ChiCTR, ChiCTR2000040048.

FINDINGS

From Sept 21, 2020, to March 3, 2021, 300 enrolees were recruited from patients visiting three primary care clinics. 55 (37%) of 150 people in the standard-of-care group (40 [53%] of 75 children and 15 [20%] of 75 older adults) and 111 (74%) of 150 in the pay-it-forward group (66 [88%] of 75 children and 45 [60%] of 75 older adults) received an influenza vaccine. People in the pay-it-forward group were more likely to receive an influenza vaccine compared with those in the standard-of-care group (adjusted odds ratio [aOR] 6·7 [95% CI 2·7-16·6] among children and 5·0 [2·3-10·8] among older adults). People in the pay-it-forward group had greater confidence in vaccine safety (aOR 2·2 [95% CI 1·2-3·9]), importance (3·1 [1·6-5·9]), and effectiveness (3·1 [1·7-5·7]). In the pay-it-forward group, 107 (96%) of 111 participants donated money for subsequent vaccinations. The pay-it-forward group had a lower economic cost (calculated as the cost without subtraction of donations) per person vaccinated (US$45·60) than did the standard-of-care group ($64·67).

INTERPRETATION

The pay-it-forward intervention seemed to be effective in improving influenza vaccine uptake and community engagement. Our data have implications for prosocial interventions to enhance influenza vaccine uptake in countries where influenza vaccines are available for a fee.

FUNDING

Bill & Melinda Gates Foundation and the UK National Institute for Health Research.

Age-dependent and sex-dependent differences in mortality from influenza-associated cardiovascular diseases among older adults in Shanghai, China: a population-based study

OBJECTIVES

Influenza epidemics lead to substantial morbidity and mortality among older adults. This study aimed to analyse and assess the age-specific and sex-specific differences in mortality rates for cardiovascular disease (CVD) associated with influenza in older adults.

DESIGN

We obtained weekly data on mortality from CVD in adults≥60 years, categorised into five age groups. We used a quasi-Poisson model and adjusted for long-term and seasonal trends and absolute humidity as confounding factors. The male-to-female ratio (M/F ratio) was an indicator for assessing sex differences.

SETTING

Shanghai, China.

PARTICIPANT

We analysed 440 107 CVD deaths in adults aged ≥60 years, including 44 913 cases positive for influenza and 1 927 487 outpatient visits for influenza-like illness from 2010 to 2019.

MAIN OUTCOME MEASURES

Age-specific and sex-specific excess CVD mortality rates in older adults for various combinations of CVDs and influenza viruses.

RESULTS

Variations were observed in the excess mortality from CVD, ischaemic heart disease (IHD) and stroke depending on the influenza types/subtypes in different age and sex categories. The ≥85 years group had the highest excess mortality rates per 100 000 persons for CVD, IHD and stroke, while influenza A (H3N2) virus accounted for the highest mortality from CVD, IHD and stroke in people aged ≥65 years. Older men had a significantly lower influenza-associated IHD mortality rate than women, with an M/F ratio of 0.77 (p<0.05).

CONCLUSIONS

Excess mortality rates for CVDs associated with influenza increased with age in older adults. The risk for influenza-associated IHD mortality was significantly higher in older women than men. Our findings will help implement targeted health strategies, including the promotion of influenza vaccination and early therapeutic intervention for the older population with CVD, to curb the influenza burden effectively.

Adult vaccination uptake strategies in low- and middle-income countries: A systematic review

BACKGROUND

Evidence-based strategies can maximize vaccination intent and uptake among adults. This systematic review summarizes the existing literature on strategies to improve vaccination intent and uptake among adults in low- and middle-income countries (LMICs) to inform future implementation in various populations and contexts.

METHODS

Eligible studies were identified through a systematic search in Medline, Embase, Cochrane Libraries, as well as grey literature databases published between January 2010 and March 2021. The search was limited to studies in LMICs that evaluated adult vaccination interventions. Data were extracted from the included studies and evaluated against the World Health Organization's Behavioral and Social Drivers of Vaccination Framework. The National Institutes of Health study quality assessment tools were used to evaluate study quality.

RESULTS

The initial literature review identified 2,854 records, 22 of which met the inclusion criteria. The majority (n = 19 or 86%) of studies were from middle-income countries, with the remaining studies (n = 3 or 13%) set in low-income countries. The majority (15/22, 68%) of interventions were multi-component. 82% (18/22) of studies addressed thoughts and feelings, 59% (13/22) addressed social processes, and 73% (16/22) addressed practical issues. Five studies reported primary outcomes of vaccination intent, and the remaining 17 reported vaccine uptake. 36% (8/22) of the studies cited statistically significant positive intervention effects on vaccination intent or uptake. Few of the included studies (6/22, 27%) were RTCs, and most studies (15/22, 68%) were of poor study quality. The studies reporting the highest increase in vaccination intent and uptake were multi-component interventions that addressed all three determinants of vaccination.

DISCUSSION

The results of this review highlight levers that can be used to encourage vaccine intent and uptake in the ongoing rollout of COVID-19 vaccines, as well as the deployment of other vaccines to adult populations in LMICs. Of the included studies, multicomponent interventions were most effective, mainly when targeting multiple determinants of vaccination. However, poor study quality indicates the need for additional research to validate these findings.

Influenza vaccination hesitancy and its determinants among elderly in China: A national cross-sectional study

BACKGROUND

The Chinese elderly face a significant threat from seasonal influenza, owing to the consistently low vaccination coverage. This study investigated the prevalence and determinants of influenza vaccination hesitancy among the Chinese elderly.

METHODS

In 2019, 3849 elderly individuals from 10 provinces in China were recruited in a cross-sectional survey. Multinomial logistic regression was applied to investigate the determinants of influenza vaccination hesitancy.

RESULTS

Among the elderly respondents, 37.18% expressed some degree of hesitancy towards influenza vaccination: 19.28% were hesitant, and 17.90% refused influenza vaccination, including 19.28% acceptors with doubts and 17.90% refusers. Only 39.10% of the respondents considered themselves as the priority group for influenza vaccination, and 13.93% reported receiving a recommendation for vaccination from healthcare workers. Respondents with higher education levels and from urban areas had significantly higher odds of vaccine hesitancy than their counterparts. Confidence in the safety of vaccines was negatively associated with vaccine hesitancy, but confidence in vaccine efficacy had no such association. Respondents who perceived themselves as highly susceptible to influenza (AOR = 0.85; 95 %CI = 0.77-0.93) and those aware of the elderly as a priority group for influenza vaccination (AOR = 0.51; 95 %CI = 0.41-0.64) had a significantly lower odds of being refusers.

CONCLUSION

This study found a high prevalence of hesitancy towards influenza vaccination among the Chinese elderly, especially well-educated and urban-dwelling respondents. The government should address vaccine hesitancy through culturally appropriate communication, subsidies for vaccination, and actively promoting vaccines through primary care professionals.

Impact of video-led educational intervention on uptake of influenza vaccine among the elderly in western China: a community-based randomized controlled trial

BACKGROUND

Influenza vaccination coverage rate among the elderly is low in China. We aimed to evaluate the impact of video-led educational intervention on influenza vaccine uptake among the Chinese elderly.

METHODS

A randomized controlled trial was conducted in 8 communities of Xi'an, a representative city in western China. Elderly aged over 60 years were randomized to the control group and intervention group (12-minute video education on influenza and its vaccination). Participants' knowledge, attitudes, and practices (KAP) of influenza was assessed by using a questionnaire survey before and after the intervention. The primary outcomes were participants' willingness to get influenza vaccinated and their actual uptake rates in the 2020-21 flu season. Secondary outcomes were the variations of pre- and post-intervention KAP scores. Intention-to-treat analysis was performed to analyze the data, and sensitivity analyses were conducted to examine the robustness of the results.

RESULTS

A total of 350 people were enrolled, with 175 individuals for each group. Participants in the intervention group were more willing to receive influenza vaccination than those in the control group (64.6% vs. 51.4%, p<0.05). The influenza vaccination uptake rate occurred in 10.3% of participants in the intervention group and 3.4% in the control group (odds ratio, 3.23; 95% CI 1.25-8.32, p<0.001). The post-intervention KAP scores in the intervention group were significantly higher compared to those in the control group (p<0.001).

CONCLUSION

Video-led education was an effective and feasible approach to improve old people's willingness and uptake of influenza vaccination in western China.

Regional-based within-year seasonal variations in influenza-related health outcomes across mainland China: a systematic review and spatio-temporal analysis

BACKGROUND

China experiences large variations in influenza seasonal activity. We aim to update and improve the current understanding of regional-based within-year variations of influenza activity across mainland China to provide evidence for the planning and optimisation of healthcare strategies.

METHODS

We conducted a systematic review and spatio-temporal meta-analysis to assess regional-based within-year variations of ILI outpatient consultation rates, influenza test positivity rates amongst both ILI outpatients and SARI inpatients, and influenza-associated excess mortality rates. We searched English and Chinese databases for articles reporting time-series data on the four influenza-related outcomes at the sub-national and sub-annual level. After synthesising the data, we reported on the mean monthly rate, epidemic onset, duration, peak and intensity.

RESULTS

We included 247 (7.7%) eligible studies in the analysis. We found within-year influenza patterns to vary across mainland China in relation to latitude and geographic location. High-latitude provinces were characterised by having short and intense annual winter epidemics, whilst most mid-latitude and low-latitude provinces experience semi-annual epidemics or year-round activity. Subtype activity varied across the country, with A/H1N1pdm09 and influenza B occurring predominantly in the winter, whereas A/H3N2 activity exhibited a latitudinal divide with high-latitude regions experiencing a winter peak, whilst mid and low-latitude regions experienced a summer epidemic. Epidemic onsets and peaks also varied, occurring first in the north and later in the southeast. We found positive associations between all influenza health outcomes. In addition, seasonal patterns at the prefecture and county-level broadly resembled their wider province.

CONCLUSIONS

This is the first systematic review to simultaneously examine the seasonal variation of multiple influenza-related health outcomes at multiple spatial scales across mainland China. The seasonality information provided here has important implications for the planning and optimisation of immunisation programmes and healthcare provision, supporting the need for regional-based approaches to address variations in local epidemiology.

Public Interest in Distribution and Determinants of Influenza and Pneumonia Vaccination during the COVID-19 Pandemic: An Infodemiology and Cross-Sectional Study from China

Background: Following the COVID-19 pandemic, global interest in influenza vaccines and pneumonia vaccines has increased significantly. We aimed to examine public interest in and actual market circulation of influenza and pneumonia vaccines before and after the initial outbreak of COVID-19 and estimate the coverage and determinants of influenza and pneumonia vaccination uptake following the COVID-19 pandemic. Methods: We obtained search volume data for vaccines using the Baidu search index and collected the numbers of vaccines issued from the National Institutes for Food and Drug Control. We also conducted a cross-sectional survey among 3346 adult residents to evaluate the coverage and determinants of influenza and pneumonia vaccination uptake in the Yangtze River delta, China, from 29 January to 4 February 2021. Results: Public searches and the number of vaccines issued for the influenza vaccines and pneumonia vaccines obviously increased after the initial outbreak of COVID-19. In the total sample, 12.5% were vaccinated against influenza, and 21.5% had at least one family member vaccinated against pneumonia. A minority of participants perceived that they were highly or very highly susceptible to influenza (15.9%) and COVID-19 (6.7%). A range of socio-economic factors and perceived susceptibility to COVID-19 were associated with influenza and pneumonia vaccination uptake. Conclusions: Public interest in and issued volumes of influenza and pneumonia vaccines increased nationally following the COVID-19 pandemic. Perceptions of high susceptibility to COVID-19 were associated with the uptake of the influenza and pneumonia vaccines. Targeted interventions were needed to improve vaccination coverage.