Seasonal influenza vaccination in middle-income countries: Assessment of immunization practices in Belarus, Morocco, and Thailand

Safety and immunogenicity of locally produced trivalent inactivated influenza vaccine (Tri Fluvac) in healthy Thai adults aged 18-64 years in Nakhon Phanom: A Phase III double blinded, three-arm, randomized, controlled trial

BACKGROUND

Domestic influenza vaccine production facilitates a sustainable supply for mitigating seasonal influenza and improves national health security by providing infrastructure and experience for pandemic vaccine production, if needed.

METHODS

A Phase III, double blind, randomized controlled trial was conducted from Sep 2019-Oct 2020 in healthy adults 18-64 years in Nakhon Phanom, Thailand. Randomization (3:3:1) compared study vaccine (Tri Fluvac), saline placebo, and an active comparator (licensed vaccine). Primary outcomes were superior efficacy compared to placebo based on RT-PCR-confirmed influenza virus infection within 12 months and non-inferiority compared to active comparator based on immunogenicity (HAI assay) at 28 days. Safety was also assessed.

RESULTS

The trial enrolled 4,284 participants (Tri Fluvac = 1,836; placebo = 1,836; active comparator = 612). There were 29 RT-PCR positive influenza infections (10 Tri Fluvac, 5.5/1,000 PY; 19 placebo, 10.4/1,000PY; 0 comparator) for an absolute protective efficacy of 46.4 (95 % CI = -22.0-76.5) compared with placebo, but the power was 43.7 %. Seroconversion difference rates between Tri Fluvac and comparator at Day 28 were 1.74 (95 % CI: -2.77, 6.25), 2.22 (-2.40, 6.84), and -0.57 (-5.41, 4.27) for A(H1N1), A(H3N2), and B strains, respectively. Adverse and severe adverse events occurred in 175 (9.5 %) Tri Fluvac, 177 (10.8 %) placebo, and 66 (10.8 %) comparator arms (p-value = 0.437, Tri Fluvac vs. comparator) CONCLUSIONS: Tri Fluvac was well tolerated, and immunogenicity was non-inferior to the active comparator, meeting U.S. Food and Drug Administration (FDA) criteria for adult vaccine licensure. Few acute respiratory infections were reported during intense COVID-19 pandemic restrictions, resulting in insufficient power to evaluate clinical efficacy.

Epidemiology of respiratory viruses among children during the SARS-CoV-2 pandemic: A systematic review and meta-analysis

OBJECTIVE

This meta-analysis aimed to assess the prevalence of respiratory viruses among children under the special conditions of the COVID-19 pandemic.

METHODS

Five databases were systematically searched to assess the pooled prevalence of various respiratory viruses in different age groups, regions, seasons, and in patients with and without confirmed SARS-CoV-2 coinfection. Moreover, we looked at the virus distribution in the first and second half of the pandemic and countries with distinct economic status. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed, and the systematic review was registered on PROSPERO (CRD42022379297).

RESULTS

Enterovirus/rhinovirus and human respiratory syncytial virus (HRSV) were the most prevalent pathogens among children. The prevalence of HRSV increased in the second half of the pandemic. The prevailing viruses vary according to the SARS-CoV-2-coinfection status, season, region, and country´s economic status.

CONCLUSION

This meta-analysis shows the epidemiology of respiratory viruses other than SARS-CoV-2 in children aged 0 to 12 years during the COVID-19 pandemic. Because major events, such as a pandemic, can alter epidemiology patterns, it is important to know them to improve health education measures, develop vaccines and medicines for vulnerable groups, as a guide for prevention strategies, and help with clinical decisions.

Parental Acceptance, Parental Hesitancy, and Uptake of Seasonal Influenza Vaccination among Children Aged 6-59 Months: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis summarises the literature on parental acceptance, parental hesitancy, uptake, and the associated factors of seasonal influenza vaccination (SIV) among children aged 6-59 months. Studies were sourced from the following platforms: PubMed, Web of Science, MEDLINE, and EMBASE databases. A random-effects model was used to evaluate the prevalence and 95% confidence intervals (CI) of parental acceptance, parental hesitancy, and SIV uptake in the last flu season and lifetime among children. A total of 36 studies were included for analysis. The overall prevalence was 64% for parental acceptance (95% CI: 51-75%), 34% for parental hesitancy (95% CI: 22-48%), 41% for SIV uptake in the last flu season (95% CI: 33-50%), and 46% for SIV uptake in a lifetime (95% CI: 20-74%). Associated factors of parental acceptance/hesitancy and uptake included the age of the children or parents, parental education level, household income level, ethnicity, and other modifiable factors, including perceived benefits, perceived barriers, perceived severity, perceived susceptibility, and cues to action related to SIV. Meta-regression analyses revealed regional differences in parental acceptance (Americas: 79% vs. Asia: 60%). The results provided implications informing us of the development of intervention programs targeting parents to improve SIV coverage among young children.

A mixed methods study of health care professionals’ attitudes towards vaccination in 15 countries

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.

Methods

A mixed-methods approach was used including an online survey (n = 1,504) in 15 countries which aimed to determine drivers of HCPs vaccine confidence and examine how these drivers vary across nations. Thirty in-depth semi-structured interviews were conducted with 10 HCPs in a subset of three countries (France, Greece and Hungry) to explore barriers to HCPs vaccine uptake and their role in addressing vaccine hesitancy among patients.

Findings.

The survey’s regression analysis identified that nurses/midwives and HCPs from Hungary, Italy, Romania and Switzerland were less confident in the safety, importance or effectiveness of vaccines in general. Morocco (35%), Turkey (53%) and Greece (69%) reported the lowest influenza vaccination coverage among HCPs. Morocco also reported the lowest rates of HCPs who were “highly likely” to recommend MMR vaccine (34%), HPV vaccine (31%) and Covid-19 vaccines (29%). More than third of HCPs reported a lack of trust in health authorities and in the information they provide. Thematic analysis revealed that concerns over the risk of side-effects associated with vaccines, preference for natural immunity, whether it was necessary to be vaccinated against influenza every year, not having any chronic disease risk factors, and vaccines mandates as the key barriers to HCPs vaccination against influenza and Covid-19.

Conclusion

HCPs have an important role in vaccination and their confidence in vaccination and health authorities must be improved as this may affect their uptake of vaccines and influence their recommendations to their patients. Investigating the impact of political, socio-economic and cultural contexts on concerns about vaccination among HCPs is also necessary.

Trends in Adult and Elderly Vaccination: Focus on Vaccination Practices in Tunisia and Morocco

Vaccine preventable diseases (VPDs) are a prevailing concern among the adult population, despite availability of vaccines. Unlike pediatric vaccination programs, adult vaccination programs lack the required reach, initiative, and awareness. Clinical studies and real-world data have proven that vaccines effectively reduce the disease burden of VPDs and increase life expectancy. In Tunisia and Morocco, the national immunization program (NIP) focuses more on pediatric vaccination and have limited vaccination programs for adults. However, some vaccination campaigns targeting adults are organized. For example, influenza vaccination campaigns prioritizing at risk adults which includes healthcare professionals, elderly, and patients with comorbidities. Women of childbearing age who have never been vaccinated or whose information is uncertain are recommended to receive tetanus vaccination. Tunisia NIP recommends rubella vaccine mainly for women of childbearing age, while in Morocco, national vaccination campaigns were organized for girls and women (up to 24 years of age) to eliminate rubella. Further, travelers from both countries are recommended to follow all requirements and recommendations in the travel destination. The objective of this manuscript is to provide an overview of the global disease burden of common VPDs including (but not limited to) meningococcal diseases, pneumococcal diseases, hepatitis, and influenza. The review also provides an overview of clinical data and guidelines/recommendations on adult vaccination practices, with special focus on Tunisia and Morocco. Some European and North American countries have concrete recommendations and strategies for adult vaccination to keep the VPDs in check. In Morocco and Tunisia, although, there are sporadic adult vaccination initiatives, the efforts still need upscaling and endorsements to boost vaccination awareness and uptake. There is a need to strengthen strategies in both countries to understand the disease burden and spread awareness. Additional studies are needed to generate economic evidence to support cost-effectiveness of vaccines. Integration of private and public healthcare systems may further improve vaccination uptake in adults.

Knowledge attitudes and practices toward seasonal influenza vaccine among pregnant women during the 2018/2019 influenza season in Tunisia

Background

The uptake and acceptance of the influenza vaccine (IV) among pregnant women remain unknown in Tunisia despite the increased influenza-related complications and death. The present study aimed to assess the IV uptake and acceptability and to describe related knowledge and attitudes among pregnant women in Tunisia.

Methods

A cross-sectional study was conducted in 84 Tunisian healthcare facilities over a period of three months (from March to May 2019). All pregnant women aged ≥18 years who sought antenatal care in related health structures were included in this study based on a multistage self-weighted sampling. We measured knowledge and attitudes towards the IV and assessed factors related to willingness for its uptake.

Results

The questionnaire was completed by 1157 pregnant women. More than half of the participants (60.2%; 95% confidence interval [CI] [57.3%–63.0%]) reported awareness about the IV. Among included PW, only 4.6%; 95% CI [3.5%–6.1%] received it during their current pregnancy. However, (36.8%; 95% CI [34.0%–39.6%]) declared their willingness to receive the vaccine in the next pregnancy. Recommendation by healthcare providers, identified to be the most trustful source of information, was the main reason for acceptance. However, the intention to accept the IV by pregnant women was significantly associated with such recommendation and perceived safety and effectiveness of this vaccine.

Conclusion

Antenatal care visits are a precious opportunity that should not be missed by health care providers and especially gynecologists to promote the IV uptake by pregnant women in Tunisia.

Workplace influenza vaccination in private hospital setting: a cost-benefit analysis

Background

Influenza illness causes several disruptions to the workforce. The absenteeism that often ensues has economic implications for employers. This study aimed to estimate the cost-benefit of influenza vaccination in a healthcare setting from the employer’s perspective.

Methods

A cross-sectional questionnaire survey was conducted in a private hospital in 2018–2019 comparing voluntary vaccinated with non-vaccinated employees with influenza vaccine. The analyses were made based on self-reporting on absenteeism and presenteeism from Influenza-like illnesses (ILIs). The costs incurred, both direct and indirect costs, were included in the study. A cost-benefit analysis was performed by measuring the cost of the vaccination program. The costs of absenteeism and reduced productivity were calculated using 3 hypothesised levels of effectiveness in the following percentage of productivity of 30%, 50%, and 70%. The costs were also calculated based on four scenarios: with and without operating income and with and without replacement. The benefits of the influenza vaccination from the employer’s perspective were analysed. The benefit to cost ratio was determined.

Results

A total of four hundred and twenty-one respondents participated. The influenza vaccination rate was 63.0%. The rate of ILI of 38.1% was significantly lower among vaccinated. The ILI-related absenteeism reported was also significantly lower amongst vaccinated employees at 30% compared to 70% non-vaccinated. Employers could save up to USD 18.95 per vaccinated employee when only labour cost was included or 54.0% of cost savings. The cost-saving rose to USD 155.56 when the operating income per employee was also included. The benefit to cost ratio confirmed that the net cost-benefit gained from the vaccination was more than the net cost of vaccination.

Conclusions

Influenza vaccination for working adults was cost-saving and cost-beneficial when translated into financial investments for the employer. A workplace vaccination demonstrates a significant cost-benefit strategy to be applied in any institutional setting.

Prevalence of antibodies against seasonal influenza A and B viruses among older adults in rural Thailand: A cross-sectional study

Assessing the seroprevalence of the high-risk individuals against the influenza virus is essential to evaluate the progress of vaccine implementation programs and establish influenza virus interventions. Herein, we identified the pre-existing cross-protection of the circulating seasonal influenza viruses among the older-aged population. A cross-sectional study was performed base on the 176 residual sera samples collected from older adults aged 60 to 95 years without a history of vaccination in rural Thailand in 2015. Sera antibody titers against influenza A and B viruses circulating between 2016 and 2019 were determined by hemagglutination inhibition assay. These findings indicated the low titers of pre-existing antibodies to circulating influenza subtypes and showed age-independent antibody titers among the old adults. Moderate seropositive rates (HAI ≥ 1:40) were observed in influenza A viruses (65.9%A(H3N2), 50.0% for A(H1N1) pdm09), and found comparatively lower rates in influenza B viruses (14% B/Yam2, 21% B/Yam3 and 25% B/Vic). Only 5% of individuals possessed broadly protective antibodies against both seasonal influenza A and B virus in this region. Our findings highlighted the low pre-existing antibodies to circulating influenza strains in the following season observed in older adults. The serological study will help inform policy-makers for health care planning and guide control measures concerning vaccination programs.

Knowledge, attitude/perception, and practice related to seasonal influenza vaccination among caregivers of young Thai children: A cross-sectional study

Background

Seasonal influenza vaccination uptake among young children in Thailand is low despite national recommendation for vaccination. We implemented a knowledge, attitude/perception, and practice survey to understand determinants of influenza vaccination in children aged six months to two years.

Methods

Using a cross-sectional design, we interviewed caregivers of 700 children in seven hospitals using a structured questionnaire to collect information on caregivers’ and children’s demographic characteristics, and caregivers’ knowledge of influenza illness and national vaccine recommendation, attitude/perception toward influenza vaccine, and information sources. We verified children’s influenza vaccination status against medical records (vaccinated vs. unvaccinated). Logistic regression was used to examine factors independently associated with children receiving influenza vaccination in the 2018 season using the dataset restricted to only children’s parents. Variables associated with vaccination at p-value ≤0.20 were included in subsequent multivariable logistic models. Significant independent determinants of children’s influenza vaccination and collinearity of covariates were assessed. The final model was constructed using a stepwise backward elimination approach with variables significant at p-value <0.05 retained in the model.

Results

During August 2018-February 2019, 700 children’s caregivers completed the questionnaire; 61 (9%) were caregivers of vaccinated children. Caregivers of the vaccinated children were statistically more likely to have higher education (61% vs. 38%; p-value<0.01) and to know of influenza illness (93% vs. 76%; p-value = 0.03) than those of the unvaccinated group. Factors associated with children receiving influenza vaccination were identifying healthcare providers as a primary source of information about influenza illness for parents (adjusted odds ratio [aOR], 2.8; 95% confidence interval [CI], 1.3–6.0), parents’ strongly agreeing with the national recommendation for influenza vaccination in young children (aOR, 2.9; 95% CI, 1.5–5.9), using health insurance provided by the government or parent’s employer for children’s doctor visits (aOR, 2.6; 95% CI, 1.1–6.6), and the children’s history of receiving influenza vaccination in the 2017 season or earlier (aOR, 3.2; 95% CI, 1.4–7.8).

Conclusion

The majority of caregivers of children in this study had knowledge of influenza illness and influenza vaccine. Caregivers reported various sources of information regarding influenza illness and the vaccine, but healthcare providers remained the most trusted source. Children’s history of influenza vaccination in prior season(s) was the strongest determinant of children being vaccinated for influenza in the current season.

Knowledge, attitudes and uptake related to influenza vaccine among healthcare workers during the 2018-2019 influenza season in Tunisia

BACKGROUND

The influenza vaccine (IV) is considered the most effective strategy to prevent seasonal influenza infection and annual vaccination of healthcare workers (HCWs) is recommended by the World Health Organization given their high mixing with patients. We assessed IV uptake among HCWs in the 2018-2019 season and explored their knowledge and attitudes regarding influenza immunization.

METHODS

A cross-sectional study was conducted in 150 representative Tunisian health facilities from March to May 2019. We recruited 1231 HCWs with direct patient contact using self-weighted multistage sampling. Univariate and multivariate logistic regression analyses permitted to assess the factors associated with IV uptake in the 2018-2019 influenza season.

RESULTS

Among 1231 health professionals enrolled in this study, less than half (36.6, 95% confidence interval [CI]: 33.9-39.4) received the IV at least once in their lives and only 15.3% (CI: 13.3-17.4) were vaccinated against influenza in the 2018-2019 influenza season. High confidence regarding IV efficacy, belief about the mandatory character of influenza vaccination for HCWs, and IV uptake in the 4 years preceding the 2018-2019 influenza season were independently associated with higher IV uptake by multivariate analysis. However, participants with high educational level were less likely to receive the IV than those with the lowest educational level.

CONCLUSIONS

Our study revealed a low vaccination rate among Tunisian HCWs confirming the importance of tailored education programs targeting this population.

Quadrivalent influenza vaccine (Sinovac Biotech) for seasonal influenza prophylaxis

INTRODUCTION

Quadrivalent Influenza Vaccine (Sinovac Biotech) is a quadrivalent split-virion-inactivated influenza vaccine approved in China in June 2020 for individuals ≥3 years of age. It contains 15 µg hemagglutinin per strain including A/H1N1, A/H3N2, B/Victoria, and B/Yamagata, which could potentially improve protection against influenza B viruses.

AREAS COVERED

In this review, we summarize the development of quadrivalent influenza vaccines in China and foreign countries, and assess the immunogenicity and safety from the phase I and III clinical trials of Quadrivalent Influenza Vaccine in individuals ≥3 years of age. We also discuss the potential application of Quadrivalent Influenza Vaccine in young children 6-35 months of age according to the results of the phase III trial.

EXPERT COMMENTARY

The immunogenicity and safety profiles of Quadrivalent Influenza Vaccine containing two A and two B strains were comparable to the trivalent vaccines for the shared strains. The addition of a second B strain to the trivalent vaccine could induce superior immune responses for the alternate B strain. Since the two B strains co-circulated worldwide, the introduction of quadrivalent influenza vaccines has been expected to be a cost-effective strategy.