Macroepidemiology of Influenza Vaccination (MIV) Study Group. The macro-epidemiology of influenza vaccination in 56 countries, 1997--2003

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.

Trends in Excess Winter Mortality (EWM) from 1900/01 to 2019/20-Evidence for a Complex System of Multiple Long-Term Trends

Trends in excess winter mortality (EWM) were investigated from the winter of 1900/01 to 2019/20. During the 1918-1919 Spanish flu epidemic a maximum EWM of 100% was observed in both Denmark and the USA, and 131% in Sweden. During the Spanish flu epidemic in the USA 70% of excess winter deaths were coded to influenza. EWM steadily declined from the Spanish flu peak to a minimum around the 1960s to 1980s. This decline was accompanied by a shift in deaths away from the winter and spring, and the EWM calculation shifted from a maximum around April to June in the early 1900s to around March since the late 1960s. EWM has a good correlation with the number of estimated influenza deaths, but in this context influenza pandemics after the Spanish flu only had an EWM equivalent to that for seasonal influenza. This was confirmed for a large sample of world countries for the three pandemics occurring after 1960. Using data from 1980 onward the effect of influenza vaccination on EWM were examined using a large international dataset. No effect of increasing influenza vaccination could be discerned; however, there are multiple competing forces influencing EWM which will obscure any underlying trend, e.g., increasing age at death, multimorbidity, dementia, polypharmacy, diabetes, and obesity-all of which either interfere with vaccine effectiveness or are risk factors for influenza death. After adjusting the trend in EWM in the USA influenza vaccination can be seen to be masking higher winter deaths among a high morbidity US population. Adjusting for the effect of increasing obesity counteracted some of the observed increase in EWM seen in the USA. Winter deaths are clearly the outcome of a complex system of competing long-term trends.

Influenza vaccination knowledge, attitudes, and practices among Tunisian elderly with chronic diseases

BACKGROUND

Generally, seasonal influenza does not cause severe infection in healthy adults, but for the elderly, an infection can pose a serious health concern. Although several measures can help prevent influenza, vaccination is considered the most effective. This study aimed to assess influenza vaccine uptake among elderly with chronic diseases in Tunisia during the 2018-2019 influenza season, and to identify knowledge, attitudes and barriers associated with influenza vaccine uptake.

METHODS

During influenza season of 2018-2019, we conducted a national cross-sectional study among elderly with chronic disease who were attending primary and secondary health care facilities in Tunisia. We collected data regarding practices, general knowledge and attitudes related to influenza and influenza vaccine, using a standardized questionnaire. A multivariate analysis by logistic regression was performed to assess the factors influencing willingness to receive influenza vaccine.

RESULTS

Among the 1191 surveyed elderly, 19.4% (95%CI 14.1-21.9) were vaccinated during the 2018-2019 influenza season and 64.7% (61.9-67.3) expressed willingness to be vaccinated in the next season regardless of vaccination status in the 2018-2019 season. Previous vaccination in the 2018-2019 influenza season was the most significantly associated factor with willingness to receive influenza vaccine (adjusted OR = 16.5 [3.7-72.4]). Significant associations were also observed between knowledge of influenza severity for the elderly as well as for those with chronic diseases and willingness to be vaccinated (p < 0.01). Likewise, participants who were convinced by flu vaccine effectiveness and those who were not concerned about vaccine side effects were more likely to be vaccinated (p < 0.001). The main reason that may lead to vaccine acceptance was a doctor's recommendation (41.1%), while the two main reasons that may lead to vaccine refusal were concerns about side effects (71.5%) and a belief that vaccine was ineffective in averting influenza illness (33.9%). Doctors were the most trusted source for information about influenza vaccine (91.5%).

CONCLUSION

Our study revealed low influenza vaccination coverage among Tunisian elderly with chronic diseases believed to be at higher risk for severe acute respiratory infections and death if infected with influenza. Treating physicians' role in promoting influenza vaccination in this high-risk group seems to be crucial.

Increasing influenza vaccination rates in solid organ transplant recipients in an outpatient transplant centre

Although influenza can lead to significant morbidity and mortality in solid organ transplant recipients, its vaccination rate among solid organ transplant recipients remains low. This study evaluates influenza vaccination among solid organ transplant recipients and compares rates before and after introducing a one-stop influenza vaccination service. In a prospective study on influenza vaccination among solid organ transplant recipients followed up from December 2014 to February 2015, 308 solid organ transplant recipients were surveyed, of which 25.0% received their annual influenza vaccination previously. Of those who have not, 60.6% were vaccinated after the education. We found most solid organ transplant recipients to be unaware of the importance of annual influenza vaccination (66.7%). Recipients with a shorter number of years post-transplant (odds ratio (OR) 0.95, 95% confidence interval (CI) 0.91–0.99) and a history of diabetes (OR 0.48, 95% CI 0.23–0.94) were more likely to receive vaccination. The incidence of influenza infection post-implementation was lower (4.9%, 2.6%; P=0.668). Solid organ transplant recipients who had had been vaccinated were associated with a lower incidence of influenza (OR 0.19, 95% CI 0.04–0.99). We conclude that the implementation of the one-stop influenza vaccination service had increased the vaccination uptake rate among solid organ transplant recipients by addressing the barriers and increasing accessibility.

Signals and trends of Guillain-Barré syndrome after the introduction of live-attenuated vaccines for influenza in the US and South Korean adverse event reporting systems

BACKGROUND

With the advent of live-attenuated, quadrivalent, and cell-cultured vaccines for influenza, there have been discussions on the safety of these vaccines compared to conventional vaccines (such as inactivated, trivalent, and egg-cultured vaccines) because of the development of neurological adverse events (AEs). This study aimed to compare the trends and safety signals in the AE reporting systems of the US and South Korea and, more particularly, to evaluate the association between influenza vaccination and Guillain-Barré syndrome (GBS).

METHODS

In total, 400,535 AE reports from the US Vaccine Adverse Event Reporting System (VAERS) and 28,766 AE reports from the Korea Adverse Event Reporting System (KAERS) between 2005 and 2017 were assessed. Disproportionality analysis was performed to detect the safety signals and examine the potential risk of GBS with influenza vaccination using the case/non-case approach.

RESULTS

In both databases, GBS was the most frequently reported AE following influenza immunization. Using the case/non-case approach, the adjusted reporting odds ratio (ROR) of GBS was 3.57 (95% confidence interval [CI], 3.16-4.03) and 3.09 (95% CI, 0.83-11.45) in the VAERS and KAERS data, respectively. People vaccinated with live-attenuated vaccines reported 2.30 times (95% CI, 1.74-3.05) more cases of GBS than those vaccinated with other types of vaccines.

CONCLUSIONS

Our analysis of the VAERS and KAERS reports for AEs following immunization (AEFI) for influenza shows the need for cautious monitoring regarding the development of GBS after influenza vaccination, particularly, after live-attenuated vaccination. However, owing to potential reporting bias caused by limited AEFI reports after the introduction of new types of influenza vaccines, further prospective safety studies are needed.

Impact of Influenza Vaccination on All-Cause Mortality and Hospitalization for Pneumonia in Adults and the Elderly with Diabetes: A Meta-Analysis of Observational Studies

Diabetes is a chronic condition that can be worsened by complications such as seasonal influenza virus infections. The aim of the present meta-analysis is the systematic retrieval and analysis of all available evidence on the effects of an influenza vaccine on diabetic patients. We conducted a systematic review and meta-analysis by searching MEDLINE, Embase and the Cochrane databases from inception until April 2019. We included all types of studies reporting on the effectiveness of influenza vaccination in adult and elderly patients with type 1 and type 2 diabetes. The Newcastle-Ottawa scale was used to assess risk of bias, the GRADE methodology was used to assess the evidence for each outcome. A total of 2261 studies were identified, of those, 6 studies completely fulfilled the inclusion criteria. In the 6 studies included in the analysis, influenza vaccination was associated with a lower mortality rate (Mantel Haenszel Odds Ratio (MH-OR), 95% CI: 0.54 (0.40; 0.74), p < 0.001). Patients who received influenza vaccination showed a lower risk of hospitalization for pneumonia (MH-OR, 95% CI: 0.89; (0.80; 0.98), p = 0.18). A sensitivity analysis using fixed effect model confirmed the results (MH-OR, 95% CI: 0.91; (0.87; 0.96); p = 0.001). The results of this meta-analysis are clinically relevant and support the recommendation for all persons with diabetes to receive influenza vaccination.

Interventions to increase seasonal influenza vaccine coverage in healthcare workers: A systematic review and meta-regression analysis

Influenza vaccination is recommended for healthcare workers (HCWs), but coverage is often low. We reviewed studies evaluating interventions to increase seasonal influenza vaccination coverage in HCWs, including a meta-regression analysis to quantify the effect of each component. Fourty-six eligible studies were identified. Domains conferring a high risk of bias were identified in most studies. Mandatory vaccination was the most effective intervention component (Risk Ratio of being unvaccinated [RRunvacc] = 0.18, 95% CI: 0.08-0.45), followed by "soft" mandates such as declination statements (RRunvacc = 0.64, 95% CI: 0.45-0.92), increased awareness (RRunvacc = 0.83, 95% CI: 0.71-0.97) and increased access (RRunvacc = 0.88, 95% CI: 0.78-1.00). For incentives the difference was not significant, while for education no effect was observed. Heterogeneity was substantial (τ(2) = 0.083). These results indicate that effective alternatives to mandatory HCWs influenza vaccination do exist, and need to be further explored in future studies.

Stepwise intervention including 1-on-1 counseling is highly effective in increasing influenza vaccination among health care workers

BACKGROUND

The influenza vaccination rate among health care workers (HCWs) remains suboptimal. We attempted to increase vaccine uptake in HCWs by nonmandatory measures, including 1-on-1 counseling.

METHODS

In 2015 we used a stepwise approach including (1) text messaging on the last day of the vaccination period, (2) extending the vaccination period by 3 days, (3) education for the low uptake group, and (4) 1-on-1 counseling for unvaccinated HCWs after the 3 interventions.

RESULTS

There were 1,433 HCWs included. By the end of the initial 3 days, the uptake rate was 80.0% (1,146/1,433). During an extension for a further 3 days, 33 additional HCWs received the vaccine. One month after starting the vaccination, 90.1% (1,291/1,433) of the HCWs were vaccinated, but this included only 76.1% (210/276) of the doctors (lowest among HCWs). After 3 educational presentations targeted at the unvaccinated doctors, no additional individuals were vaccinated in the following 2 weeks. After 1-on-1 counseling for unvaccinated HCWs, the overall vaccination rate increased to 94.7% (1,357/1,433) in 2015, higher than in the previous year (82.5%, P < .001). Of the unvaccinated doctors, 63.2% (43/68) were vaccinated, therefore achieving 92.4% (255/276) compliance, higher than the 56.5% in the previous year (152/269, P < .001).

CONCLUSIONS

Stepwise intervention including 1-on-1 counseling is effective in increasing influenza vaccination rates among HCWs.

Disease burden of 2013-2014 seasonal influenza in adults in Korea

BACKGROUND

This study was performed to investigate the disease burden of seasonal influenza in adults ≥20 years of age in Korea, based on surveillance data from the Hospital-based Influenza Morbidity & Mortality Surveillance (HIMM) network.

MATERIALS AND METHODS

The HIMM network is composed of two surveillance systems: emergency room-based and inpatients-based surveillance. A total of ten university hospitals all over the country are included in the surveillance network. The adult catchment population of the HIMM network was calculated by using the data of each hospital and the database of the Health Insurance Review and Assessment Service (HIRA) of Korea. The incidence rates of laboratory-confirmed medically-attended influenza, laboratory-confirmed influenza-related admission and laboratory-confirmed influenza-related death were calculated based on the catchment population. The socioeconomic burden of influenza was estimated using the human capital approach.

RESULTS

During the 2013-2014 influenza season, the calculated adult catchment population of the HIMM network was 1,380,000. The incidence of medically-attended laboratory-confirmed influenza infection was 242.8 per 100,000 adults. The incidence of laboratory-confirmed influenza-related admission was 57.9 per 100,000 adults. The incidence of laboratory-confirmed influenza-related death was 3.1 per 100,000 adults. The total socioeconomic cost of 2013-2014 seasonal influenza in Korean adult population was estimated as 125 million USD (1 USD = 1,100 KRW).

CONCLUSION

The disease burden of 2013-2014 seasonal influenza in Korean adult population is very high and indicates that more active prevention and control policies will be needed to decrease the burden. Additional researches will be needed to assess the burden of seasonal influenza in the Korean child population.

Factors associated with influenza vaccine uptake in older adults living in the community in Singapore

In Singapore, influenza vaccination is recommended for persons at higher risk of complications of seasonal influenza, including those with chronic medical conditions and the elderly (individuals aged ⩾65 years). We investigated the factors associated with influenza vaccine uptake based on a nationally representative sample of community-dwelling adults aged >50 years. The data for this study were obtained from the National Health Surveillance Survey (NHSS) 2013. The association between influenza vaccine uptake and socio-demographic and health-related variables was analysed using univariable and multivariable logistic regression models. Of 3700 respondents aged ⩾50 years in the NHSS, 15·2% had received seasonal influenza vaccination in the past year. Older age, single marital status and economic inactivity were the socio-demographic variables independently associated with vaccine uptake. Health-related factors which were predictive of influenza vaccine uptake were sufficient total physical activity, better self-rated health, having at least one medical condition at risk of influenza complications and a regular family doctor/general practitioner. Influenza vaccine uptake in community-dwelling older adults was low. Our findings are of relevance in the formulation of public health policies and targeted health promotion strategies to increase vaccine uptake in this population group.

Considerations for sustainable influenza vaccine production in developing countries

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Influenza vaccine.

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Vaccine manufacturing.

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Sustainability.

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Developing countries.

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Global Action Plan for Influenza vaccine.

Through its Global Action Plan for Influenza Vaccines (GAP), the World Health Organization (WHO) in collaboration with the United States Department of Health and Human Services has produced a checklist to support policy-makers and influenza vaccine manufacturers in identifying key technological, political, financial, and logistical issues affecting the sustainability of influenza vaccine production. This checklist highlights actions in five key areas that are beneficial for establishing successful local vaccine manufacturing. These five areas comprise: (1) the policy environment and health-care systems; (2) surveillance systems and influenza evidence; (3) product development and manufacturing; (4) product approval and regulation; and (5) communication to support influenza vaccination. Incorporating the checklist into national vaccine production programmes has identified the policy gaps and next steps for countries involved in GAP’s Technology Transfer Initiative. Lessons learnt from country experiences provide context and insight that complement the checklist’s goal of simplifying the complexities of influenza prevention, preparedness, and vaccine manufacturing.

Mandating influenza vaccinations for health care workers: analysing opportunities for policy change using Kingdon's agenda setting framework

Background

The consequences of annual influenza outbreaks are often underestimated by the general public. Influenza poses a serious public health threat around the world, particularly for the most vulnerable populations. Fortunately, vaccination can mitigate the negative effects of this common infectious disease. Although inoculating frontline health care workers (HCWs) helps minimize disease transmission, some HCWs continue to resist participating in voluntary immunization programs. A potential solution to this problem is government-mandated vaccination for HCWs; however, in practice, there are substantial barriers to the adoption of such policies. The purpose of this paper is to identify the likelihood of adopting a policy for mandatory immunization of HCWs in Ontario based on a historical review of barriers to the agenda setting process.

Methods

Documents from secondary data sources were analysed using Kingdon’s agenda setting framework of three converging streams leading to windows of opportunity for possible policy adoption.

Results

The problems, politics, and policies streams of Kingdon’s framework have converged and diverged repeatedly over an extended period (policy windows have opened and closed several times). In each instance, a technically feasible solution was available. However, despite the evidence supporting the value of HCW immunization, alignment of the three agenda setting streams occurred for very short periods of time, during which, opposition lobby groups reacted, making the proposed solution less politically acceptable.

Conclusions

Prior to the adoption of any new policies, issues must reach a government’s decision agenda. Based on Kingdon’s agenda setting framework, this only occurs when there is alignment of the problems, politics, and policies streams. Understanding this process makes it easier to predict the likelihood of a policy being adopted, and ultimately implemented. Such learning may be applied to policy issues in other jurisdictions. In the case of mandatory influenza vaccinations for HCWs in Ontario, it seems highly unlikely that a new policy will be adopted until perception of the problem’s importance is sufficient to overcome the political opposition to implementing a solution and thus, create a window of opportunity that is open long enough to support change.

Exploring and Promoting Prosocial Vaccination: A Cross-Cultural Experiment on Vaccination of Health Care Personnel

Influenza vaccination for health care personnel (HCP) is recommended particularly because it indirectly protects patients from contracting the disease. Vaccinating can therefore be interpreted as a prosocial act. However, HCP vaccination rates are often far too low to prevent nosocomial infections. Effective interventions are needed to increase HCP's influenza vaccine uptake. Here we devise a novel tool to experimentally test interventions that aim at increasing prosocially motivated vaccine uptake under controlled conditions. We conducted a large-scale and cross-cultural experiment with participants from countries with either a collectivistic (South Korea) or an individualistic (USA) cultural background. Results showed that prosocially motivated vaccination was more likely in South Korea compared to the US, mediated by a greater perception of vaccination as a social act. However, changing the default of vaccination, such that participants had to opt out rather than to opt in, increased vaccine uptake in the US and therefore compensated for the lower level of prosocial vaccination. In sum, the present study provides both a novel method to investigate HCP influenza vaccination behavior and interventions to increase their vaccine uptake.

A systematic review of ethical issues in vaccine studies involving pregnant women

BACKGROUND

Immunization during pregnancy can provide protection for mother and child. However, there have been only a limited number of studies documenting the efficacy and safety of this strategy.

AIMS

To determine the extent and nature of subject matter related to ethics in maternal immunization by systematically documenting the spectrum of ethical issues in vaccine studies involving pregnant women.

METHOD

We conducted a systematic literature review of published works pertaining to vaccine and therapeutic studies involving pregnant women through searches of PubMed, EMBASE, Web of Science, the Cochrane Database, and ClinicalTrials.gov. We selected literature meeting the inclusion criteria published between 1988 and June 2014. We systematically abstracted subject matter pertaining to ethical issues in immunization studies during pregnancy. Immunization-specific ethical issues were matched and grouped into major categories and subcategories.

RESULTS

Seventy-seven published articles met the inclusion criteria. Published articles reported findings on data that had been collected in 26 countries, the majority of which were classified as high-income or upper-middle-income nations according to World Bank criteria. Review of these publications produced 60 immunization-specific ethical issues, grouped into six major categories. Notably, many studies demonstrated limited acknowledgment of key ethical issues including the rights and welfare of participants. Additionally, there was no discussion pertaining to the ethics of program implementation, including integration of maternal immunization programs into existing routine immunization programs.

CONCLUSION

This review of ethical issues in immunization studies of pregnant women can be used to help inform future vaccine trials in this important population. Consistent documentation of these ethical issues by investigators will facilitate a broader and more nuanced discussion of ethics in immunization of pregnant women - offering new and valuable insights for programs developed to prevent disease in newborn children in low- and middle-income countries.

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics - a systematic literature review

AIM

The evidence needed for tropical countries to take informed decisions on influenza vaccination is scarce. This article reviews policy, availability, use and effectiveness of seasonal influenza vaccine in tropical and subtropical countries.

METHOD

Global health databases were searched in three thematic areas - policy, availability and protective benefits in the context of human seasonal influenza vaccine in the tropics and subtropics. We excluded studies on monovalent pandemic influenza vaccine, vaccine safety, immunogenicity and uptake, and disease burden.

RESULTS

Seventy-four countries in the tropics and subtropics representing 60% of the world's population did not have a national vaccination policy against seasonal influenza. Thirty-eight countries used the Northern Hemisphere and 21 countries the Southern Hemisphere formulation. Forty-six countries targeted children and 57 targeted the elderly; though, the age cut-offs varied. Influenza vaccine supply increased twofold in recent years. However, coverage remained lower than five per 1000 population. Vaccine protection against laboratory-confirmed influenza in the tropics ranged from 0% to 42% in the elderly, 20-77% in children and 50-59% in healthy adults. Vaccinating pregnant women against seasonal influenza prevented laboratory-confirmed influenza in both mothers (50%) and their infants <6 months (49-63%).

CONCLUSION

Guidelines on vaccine composition, priority risk groups and vaccine availability varied widely. The evidence on vaccine protection was scarce. Countries in the tropics and subtropics need to strengthen and expand their evidence-base required for making informed decisions on influenza vaccine introduction and expansion, and how much benefit to expect.

Influenza Seasonality in the Tropics and Subtropics - When to Vaccinate?

BACKGROUND

The timing of the biannual WHO influenza vaccine composition selection and production cycle has been historically directed to the influenza seasonality patterns in the temperate regions of the northern and southern hemispheres. Influenza activity, however, is poorly understood in the tropics with multiple peaks and identifiable year-round activity. The evidence-base needed to take informed decisions on vaccination timing and vaccine formulation is often lacking for the tropics and subtropics. This paper aims to assess influenza seasonality in the tropics and subtropics. It explores geographical grouping of countries into vaccination zones based on optimal timing of influenza vaccination.

METHODS

Influenza seasonality was assessed by different analytic approaches (weekly proportion of positive cases, time series analysis, etc.) using FluNet and national surveillance data. In case of discordance in the seasonality assessment, consensus was built through discussions with in-country experts. Countries with similar onset periods of their primary influenza season were grouped into geographical zones.

RESULTS

The number and period of peak activity was ascertained for 70 of the 138 countries in the tropics and subtropics. Thirty-seven countries had one and seventeen countries had two distinct peaks. Countries near the equator had secondary peaks or even identifiable year-round activity. The main influenza season in most of South America and Asia started between April and June. The start of the main season varied widely in Africa (October and December in northern Africa, April and June in Southern Africa and a mixed pattern in tropical Africa). Eight "influenza vaccination zones" (two each in America and Asia, and four in Africa and Middle East) were defined with recommendations for vaccination timing and vaccine formulation. The main limitation of our study is that FluNet and national surveillance data may lack the granularity to detect sub-national variability in seasonality patterns.

CONCLUSION

Distinct influenza seasonality patterns, though complex, could be ascertained for most countries in the tropics and subtropics using national surveillance data. It may be possible to group countries into zones based on similar recommendations for vaccine timing and formulation.

The Impact of Patient's Socio-Demographic Characterictics, Comorbidities and Attitudes on Flu Vaccination Uptake in Family Practice Settings

OBJECTIVES

In Slovenia, the role of family physicians in primary care and preventive procedures is very important. Influenza vaccination rates in Slovenia are low. The reasons for low vaccination rates in Slovenia were not clear. We suppose that patient's beliefs and attitudes are important factors. We assessed patients' opinions regarding the acceptance of flu vaccination by their family physicians and their beliefs and attitudes about flu and vaccination. The aim was to check out factors that influence the decision to take the vaccine in family physician offices.

METHODS

This was a cross-sectional, multicenter, observational study in the Styria region in Slovenia. We included patients from seven family physicians during regular office visits. They filled in a questionnaire about their general demographic data and attitudes regarding influenza and vaccination. The main outcome was the decision to be vaccinated.

RESULTS

The logistic regression model identified five predictors for influenza vaccination, namely: heart disease, previous vaccination, an agreement with the beliefs 'the vaccination is an efficient measure to prevent influenza', 'after the vaccination there are usually no important side effects' and 'the vaccination is also recommended for a healthy adult person'. The belief that vaccinations harm the immune system is negatively associated with vaccination.

CONCLUSIONS

Patients' beliefs are an important factor to decide for vaccination or not. Family physician teams should discuss with patients their beliefs and concerns about vaccination.

Influenza vaccination uptake and its socioeconomic determinants in the older adult Iranian population: A national study

BACKGROUND

The relationship between socioeconomic status and influenza vaccine uptake has a different pattern in different societies. The objective of this study was to assess the socioeconomic factors influencing influenza vaccination uptake in the older adult Iranian population.

METHODS

In this cross-sectional study, 1,350 Iranian adults aged ≥60 years were selected using a multistage sampling method. Self-report questionnaires were administered to collect information on the status of influenza vaccine uptake within the last year.

RESULTS

Overall, 10.4% of the older adult Iranian population had received influenza vaccinations within the last year. Several determinants were associated with influenza vaccination uptake, such as current occupation, education level, ethnicity, source of income, financial support from relatives, satisfaction with income, type of health insurance, and having complementary health insurance for outpatient services. Other factors, such as age, sex, marital status, residential area, and having health insurance, had no influence on the probability of vaccine uptake. After adjusting for desired variables, we found that having an occupation (odds ratio [OR] = 2.08; 95% confidence interval [CI], 1.08-4.02) and having complementary health insurance for outpatient services (OR = 1.65; 95% CI, 1.06-2.56) remained associated with higher influenza vaccine uptake.

CONCLUSIONS

The influenza vaccination rate in older adult Iranians was found to be low. Occupation and having complementary health insurance were associated with influenza vaccination uptake among Iranian older adults. Considering the mentioned variables in future studies is advised.

The cost of acute respiratory infections in Northern India: a multi-site study

Background

Despite the high mortality and morbidity resulting from acute respiratory infections (ARI) globally, there are few data from low-income countries on costs of ARI to inform public health policy decisions We conducted a prospective survey to assess costs of ARI episodes in selected primary, secondary, and tertiary healthcare facilities in north India where no respiratory pathogen vaccine is routinely recommended.

Methods

Face-to-face interviews were conducted among a purposive sample of patients with ARI from healthcare facilities. Data were collected on out-of-pocket costs of hospitalization, medical consultations, medications, diagnostics, transportation, lodging, and missed work days. Telephone surveys were conducted two weeks after medical encounters to ask about subsequent missed work and costs incurred. Costs of prescriptions and diagnostics in public facilities were supplemented with WHO-CHOICE estimates of hospital bed costs. Missed work days were assigned cost based on the national annual per capita income (US$1,104). Non-medically attended ARI cases were identified from an ongoing community-based ARI surveillance project in Faridabad.

Results

During September 2012-March 2013, 1766 patients with ARI were enrolled, including 451 hospitalized patients, 1056 outpatients, and 259 non-medically attended patients. The total direct cost of an ARI episode requiring outpatient care was US$4- $6 for public and $3-$10 for private institutions based on age groups. The total direct cost of an ARI episode requiring hospitalized care was $54-$120 in public and $135-$355 in private institutions. The cost of ARI among those hospitalized was highest among persons aged > = 65 years and lowest among children aged < 5 years. Indirect costs due to missed work days were 16-25% of total costs. The direct out-of-pocket cost of hospitalized ARI was 34% of annual per capita income.

Conclusions

The cost of hospitalized ARI episodes in India is high relative to median per capita income. Data from this study can inform evaluations of the cost effectiveness of proven ARI prevention strategies such as vaccination.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1685-6) contains supplementary material, which is available to authorized users.

Suboptimal effectiveness of the 2011-2012 seasonal influenza vaccine in adult Korean populations

Background

The effectiveness of the 2011–2012 seasonal influenza vaccine was evaluated in adult Korean populations with regard to how well it could prevent laboratory-confirmed influenza and influenza-related complications.

Materials and Methods

A retrospective case-control and retrospective cohort study was conducted among patients who visited four selected hospitals from September 2011 to May 2012. The analysis included 1,130 laboratory-confirmed influenza patients. For each influenza case, one control patient was chosen at a ratio of 1:1. A control was defined as an age group-matched patient who visited the same hospital with influenza-like illness within 48 hours of symptom onset but for whom laboratory tests were negative for influenza. Age group and visit date were matched between the cases and controls. Vaccine effectiveness (VE) was defined as [100 × (1-odds ratio for influenza in vaccinated versus non-vaccinated persons)]. The patients with laboratory-confirmed influenza were followed for at least one month through reviewing the medical records and conducting a telephone interview.

Results

The VE of the 2011–2012 seasonal influenza vaccine was 3.8% [95% confidence interval (CI), -16.5% to 20.6%] for preventing laboratory-confirmed influenza, -16.1% (95% CI, -48.3 to 9.1) for influenza A and 26.2% (95% CI, -2.6 to 46.2) for influenza B. The age-specific adjusted VE was 0.3% (95% CI, -29.4 to 23.1) among participants aged 19 to 49 years, 11.9% (95% CI, -34.3 to 42.2) among those aged 50 to 64 years and -3.9% (-60.1 to 32.5) among those aged ≥65 years. The adjusted VE for preventing any influenza-related complications was -10.7% (95% CI, -41.1% to 42.2%).

Conclusions

The 2011–2012 seasonal influenza vaccine was not effective in preventing laboratory-confirmed influenza or influenza-related complications in adult Korean populations.

The influence of partial public reimbursement on vaccination uptake in the older population: a cross-sectional study

Background

Flu vaccination is recommended annually for high risk groups. However, in Ireland, free access to vaccination is not universal for those in high risk groups; the vaccine and consultation are only free for those with a medical card, a means tested scheme. Few private health insurance policies cover the cost of attendance for vaccination in general practice. The aim was to examine the influence of this reimbursement policy on vaccination coverage among older adults.

Methods

Cross-sectional wave 1 data from The Irish Longitudinal Study on Ageing (TILDA) were analysed (2009–2011). TILDA is a nationally representative prospective cohort study of adults aged ≥50, sampled using multistage stratified clustered sampling. Self-reported entitlement to healthcare was categorised as 1) medical card only 2) private health insurance only, 3) both and 4) neither. The outcome was responses to ‘have you ever had a flu shot’. Multivariate logistic regression was used, adjusting for age and need.

Results

68.6% of those defined as clinically high-risk received the flu vaccination in the past (95% CI = 67-71%). Those with a medical card were almost twice as likely to have been vaccinated, controlling for age and chronic illness (OR = 1.9, 95% CI = 1.5-2.5, p = <0.001).

Conclusions

Having a medical card increased the likelihood of being vaccinated, independent of age and need. The mismatch between vaccination guidelines and reimbursement policy is creating unequal access to recommended services among high risk groups.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1356-7) contains supplementary material, which is available to authorized users.

Seasonal influenza vaccine coverage among high-risk populations in Thailand, 2010-2012

Background

The Advisory Committee on Immunization Practice of Thailand prioritizes seasonal influenza vaccinations for populations who are at highest risk for serious complications (pregnant women, children 6 months–2 years, persons ≥65 years, persons with chronic diseases, obese persons), and health-care personnel and poultry cullers. The Thailand government purchases seasonal influenza vaccine for these groups. We assessed vaccination coverage among high-risk groups in Thailand from 2010 to 2012.

Methods

National records on persons who received publicly purchased vaccines from 2010 to 2012 were analyzed by high-risk category. Denominator data from multiple sources were compared to calculate coverage. Vaccine coverage was defined as the proportion of individuals in each category who received the vaccine. Vaccine wastage was defined as the proportion of publicly purchased vaccines that were not used.

Results

From 2010 to 2012, 8.18 million influenza vaccines were publicly purchased (range, 2.37–3.29 million doses/year), and vaccine purchases increased 39% over these years. Vaccine wastage was 9.5%. Approximately 5.7 million (77%) vaccine doses were administered to persons ≥65 years and persons with chronic diseases, 1.4 million (19%) to healthcare personnel/poultry cullers, 82,570 (1.1%) to children 6 months–2 years, 78,885 (1.1%) to obese persons, 26,481 (0.4%) to mentally disabled persons, and 17,787 (0.2%) to pregnant women. Between 2010 and 2012, coverage increased among persons with chronic diseases (8.6% versus 14%; p < 0.01) and persons ≥65 years (12%, versus 20%; p < 0.01); however, coverage decreased for mentally disabled persons (6.1% versus 4.9%; p < 0.01), children 6 months–2 years (2.3% versus 0.9%; p < 0.01), pregnant women (1.1% versus 0.9%; p < 0.01), and obese persons (0.2% versus 0.1%; p < 0.01).

Conclusions

From 2010 to 2012, the availability of publicly purchased vaccines increased. While coverage remained low for all target groups, coverage was highest among persons ≥65 years and persons with chronic diseases. Annual coverage assessments are necessary to promote higher coverage among high-risk groups in Thailand.

Influenza vaccines: an Asia-Pacific perspective

This article provides an overview of some aspects of seasonal, pre-pandemic and pandemic influenza vaccines and initiatives aimed to increase influenza vaccine use within the Asia-Pacific region. Expanding the use of influenza vaccines in the Asia-Pacific region faces many challenges. Despite the recent regional history for the emergence of novel viruses, SARS, the H5N1 and H7N9, and the generation of and global seeding of seasonal influenza viruses and initiatives by WHO and other organisations to expand influenza awareness, the use of seasonal influenza vaccines remains low. The improvement in current vaccine technologies with the licensing of quadrivalent, live-attenuated, cell culture-based, adjuvanted and the first recombinant influenza vaccine is an important step. The development of novel influenza vaccines able to provide improved protection and with improved manufacturing capacity is also advancing rapidly. However, of ongoing concern are seasonal influenza impact and the low use of seasonal influenza vaccines in the Asia-Pacific region. Improved influenza control strategies and their implementation in the region are needed. Initiatives by the World Health Organization (WHO), and specifically the Western Pacific Regional Office of WHO, are focusing on consistent vaccine policies and guidelines in countries in the region. The Asian-Pacific Alliance for the Control of Influenza (APACI) is contributing through the coordination of influenza advocacy initiates.

Trends in influenza vaccination behaviours--results from the CoPanFlu cohort, France, 2006 to 2011

Controversies over the effectiveness and safety of the pandemic influenza A(H1N1)pdm09 vaccine in 2009/10 may have altered the influenza vaccination coverage in France after the pandemic season. The purpose of this study was to determine whether the pandemic affected seasonal influenza vaccination behaviours in the general population by analysing vaccination behaviours from 2006/07 to 2011/12 among the 1,451 subjects of the Cohort for Pandemic Influenza (CoPanFlu) France.We found that vaccination behaviours in 2010/11 and 2011/12 significantly differed from behaviours before the pandemic, with the notable exception of the targeted risk groups for seasonal influenza-related complications. Among the population with no risk factors,the post-pandemic influenza vaccine coverage decreased, with people aged 15 to 24 years and 45to 64 years being most likely to abandon vaccination.Therefore, this study documents a moderate negative effect of the 2009/10 pandemic episode on vaccination behaviours in the French metropolitan population that was apparent also in the following two seasons.Moreover, it does not exclude that the general trend of reduced vaccination has also affected certain targeted groups at high risk for complications.

Effect of influenza vaccination of healthcare personnel on morbidity and mortality among patients: systematic review and grading of evidence

BACKGROUND

Influenza vaccination of healthcare personnel (HCP) is recommended in >40 countries. However, there is controversy surrounding the evidence that HCP vaccination reduces morbidity and mortality among patients. Key factors for developing evidence-based recommendations include quality of evidence, balance of benefits and harms, and values and preferences.

METHODS

We conducted a systematic review of randomized trials, cohort studies, and case-control studies published through June 2012 to evaluate the effect of HCP influenza vaccination on mortality, hospitalization, and influenza cases in patients of healthcare facilities. We pooled trial results using meta-analysis and assessed evidence quality using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We identified 4 cluster randomized trials and 4 observational studies conducted in long-term care or hospital settings. Pooled risk ratios across trials for all-cause mortality and influenza-like illness were 0.71 (95% confidence interval [CI], .59-.85) and 0.58 (95% CI, .46-.73), respectively; pooled estimates for all-cause hospitalization and laboratory-confirmed influenza were not statistically significant. The cohort and case-control studies indicated significant protective associations for influenza-like illness and laboratory-confirmed influenza. No studies reported harms to patients. Using GRADE, the quality of the evidence for the effect of HCP vaccination on mortality and influenza cases in patients was moderate and low, respectively. The evidence quality for the effect of HCP vaccination on patient hospitalization was low. The overall evidence quality was moderate.

CONCLUSIONS

The quality of evidence is higher for mortality than for other outcomes. HCP influenza vaccination can enhance patient safety.

Influenza-associated excess mortality in southern Brazil, 1980-2008

In order to estimate influenza-associated excess mortality in southern Brazil, we applied Serfling regression models to monthly mortality data from 1980 to 2008 for pneumonia/influenza- and respiratory/circulatory-coded deaths for all ages and for those aged ≥60 years. According to viral data, 73∙5% of influenza viruses were detected between April and August in southern Brazil. There was no clear influenza season for northern Brazil. In southern Brazil, influenza-associated excess mortality was 1∙4/100,000 for all ages and 9∙2/100,000 person-years for persons aged ≥60 years using underlying pneumonia/influenza-coded deaths and 10∙0/100,000 for all ages and 86∙6/100,000 person-years for persons aged ≥60 years using underlying respiratory/circulatory-coded deaths. Influenza-associated excess mortality rates for southern Brazil are similar to those published for other countries. Our data support the need for continued influenza surveillance to guide vaccination campaigns to age groups most affected by this virus in Brazil.

A review of the evidence to support influenza vaccine introduction in countries and areas of WHO's Western Pacific Region

Background

Immunization against influenza is considered an essential public health intervention to control both seasonal epidemics and pandemic influenza. According to the World Health Organization (WHO), there are five key policy and three key programmatic issues that decision-makers should consider before introducing a vaccine. These are (a) public health priority, (b) disease burden, (c) efficacy, quality and safety of the vaccine, (d) other inventions, (e) economic and financial issues, (f) vaccine presentation, (g) supply availability and (h) programmatic strength. We analyzed the body of evidence currently available on these eight issues in the WHO Western Pacific Region.

Methodology/Principal Findings

Studies indexed in PubMed and published in English between 1 January 2000 and 31 December 2010 from the 37 countries and areas of the Western Pacific Region were screened for keywords pertaining to the five policy and three programmatic issues. Studies were grouped according to country income level and vaccine target group. There were 133 articles that met the selection criteria, with most (90%) coming from high-income countries. Disease burden (n = 34), vaccine efficacy, quality and safety (n = 27) and public health priority (n = 27) were most frequently addressed by studies conducted in the Region. Many studies assessed influenza vaccine policy and programmatic issues in the general population (42%), in the elderly (24%) and in children (17%). Few studies (2%) addressed the eight issues relating to pregnant women.

Conclusions/Significance

The evidence for vaccine introduction in countries and areas in this Region remains limited, particularly in low- and middle-income countries that do not currently have influenza vaccination programmes. Surveillance activities and specialized studies can be used to assess the eight issues including disease burden among vaccine target groups and the cost-effectiveness of influenza vaccine. Multi-country studies should be considered to maximize resource utilization for cross-cutting issues such as vaccine presentation and other inventions.

Influenza and respiratory syncytial virus are the major respiratory viruses detected from prospective testing of pediatric and adult coronial autopsies

BACKGROUND

To ascertain the full mortality of influenza and other respiratory viruses, the testing of community autopsy specimens is essential.

METHODS

Respiratory virus PCR and culture were performed on 2418 fresh unfrozen respiratory samples collected from 1611 coronial cases where the death was either unknown or infection was suspected, from July 2007 to June 2011, to detect the common respiratory viruses in children and adults, using standardized microbiological testing.

RESULTS

The respiratory virus positive rate was 8·3% (134 cases) with a peak of 28% (42 of 151 cases) in children under 10 years of age. Influenza virus was the commonest respiratory virus (50 cases, 3%), followed by respiratory syncytial virus (RSV) (30 cases, 2%). All tested respiratory viruses were found in children, most commonly adenovirus, enterovirus and RSV, and influenza A and RSV predominated in those over 60 years, but coinfection was uncommon. Almost all influenza cases occurred when influenza was widely circulating in the community but few were diagnosed pre-mortem. Influenza and RSV detection was associated with bronchitis or bronchiolitis in 7 (9%) of the 80 cases and caused pneumonia in 14 (0·8%) deaths overall.

CONCLUSIONS

Our prospective review of respiratory viruses using standardized testing found a single lower respiratory tract autopsy specimen for respiratory virus PCR would detect most community infections at the time of death.

Social determinants of health and seasonal influenza vaccination in adults ≥65 years: a systematic review of qualitative and quantitative data

BACKGROUND

Vaccination against influenza is considered the most important public health intervention to prevent unnecessary hospitalizations and premature deaths related to influenza in the elderly, though there are significant inequities among global influenza vaccine resources, capacities, and policies. The objective of this study was to assess the social determinants of health preventing adults ≥ 65 years old from accessing and accepting seasonal influenza vaccination.

METHODS

A systematic search was performed in January 2011 using MEDLINE, ISI - Web of Science, PsycINFO, and CINAHL (1980-2011). Reference lists of articles were also examined. Selection criteria included qualitative and quantitative studies written in English that examined social determinants of and barriers against seasonal influenza vaccination among adults ≥ 65 years. Two authors performed the quality assessment and data extraction. Thematic analysis was the main approach for joint synthesis, using identification and juxtaposition of themes associated with vaccination.

RESULTS

Overall, 58 studies were analyzed. Structural social determinants such as age, gender, marital status, education, ethnicity, socio-economic status, social and cultural values, as well as intermediary determinants including housing-place of residence, behavioral beliefs, social influences, previous vaccine experiences, perceived susceptibility, sources of information, and perceived health status influenced seasonal influenza vaccination. Healthcare system related factors including accessibility, affordability, knowledge and attitudes about vaccination, and physicians' advice were also important determinants of vaccination.

CONCLUSIONS

Our results demonstrate that the ability of adults ≥ 65 years to receive seasonal influenza vaccine is influenced by structural, intermediate, and healthcare-related social determinants which have an impact at the health system, provider, and individual levels.

Case-control study of the effectiveness of the 2010-2011 seasonal influenza vaccine for prevention of laboratory-confirmed influenza virus infection in the Korean adult population

We evaluated the effectiveness of the 2010-2011 seasonal influenza vaccine for preventing laboratory-confirmed influenza in a South Korean population. A retrospective case-control study was conducted among patients who visited selected hospitals from September 2010 to May 2011. A total of 483 laboratory-confirmed influenza patients were included in the analysis as case subjects. For each case patient, two types of control patients were chosen at a ratio of 1:1:1, and 966 control subjects were selected. Vaccine effectiveness (VE) was defined as 100 × (1 - odds ratio for influenza in vaccinated versus nonvaccinated persons). The VE of the 2010-2011 seasonal influenza vaccine was 49.5% to 45.8% for both influenza A and B viruses and 50.8% to 47.2% for influenza A virus, according to the control type. The age-specific adjusted VE was 50.8% to 46.5% among subjects aged 19 to 49 years and 58.7% to 63.3% among those aged 50 to 64 years, according to the control type. Statistically significant VE was not found among those aged ≥65 years or against influenza B virus. The 2010-2011 seasonal influenza vaccine was effective for preventing laboratory-confirmed influenza, especially for influenza A virus, in a South Korean population. Evidence of the effectiveness of the influenza vaccine in older adults or against influenza B virus was not found.

Protecting patients, protecting healthcare workers: a review of the role of influenza vaccination

AIM

Many health authorities recommend routine influenza vaccination for healthcare workers (HCWs), and during the 2009 A (H1N1) pandemic, the World Health Organization (WHO) recommended immunization of all HCWs worldwide. As this remains an important area of policy debate, this paper examines the case for vaccination, the role of local guidelines, barriers to immunization and initiatives to increase uptake.

BACKGROUND

Seasonal influenza is a major threat to public health, causing up to 1 million deaths annually. Extensive evidence supports the vaccination of priority groups, including HCWs. Immunization protects HCWs themselves, and their vulnerable patients from nosocomial influenza infections. In addition, influenza can disrupt health services and impact healthcare organizations financially. Immunization can reduce staff absences, offer cost savings and provide economic benefits.

METHODS

This paper reviews official immunization recommendations and HCW vaccination studies, including a recent International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) survey of 26 countries from each region of the world.

RESULTS

HCW immunization is widely recommended and supported by the WHO. In the IFPMA study, 88% of countries recommended HCW vaccination, and 61% supported this financially (with no correlation to country development status). Overall, coverage can be improved, and research shows that uptake may be impacted by lack of conveniently available vaccines and misconceptions regarding vaccine safety/efficacy and influenza risk.

CONCLUSIONS

Many countries recommend HCW vaccination against influenza. In recent years, there has been an increased uptake rate among HCWs in some countries, but not in others. Several initiatives can increase coverage, including education, easy access to free vaccines and the use of formal declination forms. The case for HCW vaccination is clear, and in an effort to further accelerate uptake as a patient safety measure, an increasing number of healthcare organizations, particularly in the USA, are implementing mandatory immunization policies, similar to other obligatory hygiene measures. However, it would be desirable if similar high vaccination uptake rates could be achieved through voluntary procedures.

Intradermal vaccination to protect against yellow fever and influenza

The viral infections yellow fever and influenza can lead to large epidemics, which may deplete limited vaccine supplies. The intradermal vaccination route of yellow fever and influenza vaccines has received renewed attention, because it allows dose reduction without loss of efficacy. In this chapter, we review these two vaccines, the history of vaccine development, correlates of protection, immune response to vaccination and current knowledge concerning intradermal vaccination, including the immunological background, both in healthy subjects and immunocompromized individuals.

Effect modification of environmental factors on influenza-associated mortality: a time-series study in two Chinese cities

BACKGROUND

Environmental factors have been associated with transmission and survival of influenza viruses but no studies have ever explored the role of environmental factors on severity of influenza infection.

METHODS

We applied a Poisson regression model to the mortality data of two Chinese metropolitan cities located within the subtropical zone, to calculate the influenza associated excess mortality risks during the periods with different levels of temperature and humidity.

RESULTS

The results showed that high absolute humidity (measured by vapor pressure) was significantly (p < 0.05) associated with increased risks of all-cause and cardiorespiratory deaths, but not with increased risks of pneumonia and influenza deaths. The association between absolute humidity and mortality risks was found consistent among the two cities. An increasing pattern of influenza associated mortality risks was also found across the strata of low to high relative humidity, but the results were less consistent for temperature.

CONCLUSIONS

These findings highlight the need for people with chronic cardiovascular and respiratory diseases to take extra caution against influenza during hot and humid days in the subtropics and tropics.

Influenza associated mortality in the subtropics and tropics: results from three Asian cities

Influenza has been well documented to significantly contribute to winter increase of mortality in the temperate countries, but its severity in the subtropics and tropics was not recognized until recently and geographical variations of disease burden in these regions remain poorly understood. In this study, we applied a standardized modeling strategy to the mortality and virology data from three Asian cities: subtropical Guangzhou and Hong Kong, and tropical Singapore, to estimate the disease burden of influenza in these cities. We found that influenza was associated with 10.6, 13.4 and 8.3 deaths per 100,000 population in Guangzhou, Hong Kong and Singapore, respectively. The annual rates of excess deaths in the elders were estimated highest in Guangzhou and lowest in Singapore. The excess death rate attributable to A/H1N1 subtype was found slightly higher than the rates attributable to A/H3N2 during the study period of 2004-2006 based on the data from Hong Kong and Guangzhou. Our study revealed a geographical variation in the disease burden of influenza in these subtropical and tropical cities. These results highlight a need to explore the determinants for severity of seasonal influenza.

Safety and immunogenicity of a new trivalent inactivated split-virus influenza vaccine in healthy Korean children: a randomized, double-blinded, active-controlled, phase III study

We report results of a randomized, double-blinded, active-controlled, phase III study conducted to evaluate the immunogenicity and safety of a new trivalent inactivated split-virus influenza vaccine (GC501) manufactured by the Green Cross Corporation in Korea. A total of 283 healthy children aged 6 months to < 18 yr were randomized to receive either GC501 or control. Of the GC501 recipients, seroconversion occurred in 48.5% for A/H1N1, 67.7% for A/H3N2 and 52% for influenza B. The proportion of subjects who had post-vaccination hemagglutination-inhibition titers of 1:40 or greater was 90.7% for A/H1N1, 86.8% for A/H3N2 and 82.4% for influenza B in the GC501 recipients. No serious adverse events related to vaccination, or withdrawals because of adverse events were reported. The majority of solicited adverse events were mild in intensity. GC501 vaccine has good tolerability and favorable immunogenicity in children aged 6 months to < 18 yr. The addition of one more brand of influenza vaccine may allow for better global accessibility of vaccine for epidemics or future pandemics.

Seasonal influenza vaccine provision in 157 countries (2004-2009) and the potential influence of national public health policies

Seasonal influenza places a major burden on public health. Consequently, the World Health Organization (WHO) and over 40% of national governments recommend vaccination of at-risk groups. However, no systematic global data are available to assess vaccine provision nor the effect of immunization policies. To address this situation, IFPMA IVS surveyed global vaccine supply, covering 157 countries from 2004 to 2009. The study also used UN data and a novel vaccine provision "hurdle" rate (set at 15.9% of the population, based on WHO immunization recommendations for the elderly) to compare vaccine supply with development status. In a sub-group of 26 countries, the level of vaccine provision was also correlated to the presence/absence of specific vaccination policies. Between 2004 and 2009, global annual vaccine provision increased 72% to 449 million doses. Europe and the Americas accounted for 75% to 80% of the total each year, with several countries in these regions, as well as China, Japan and Thailand, achieving notable increases during the study period. However, despite the global growth, only 20% of countries reached the study's modest "hurdle" rate. On a per capita basis, dose distribution did not correlate directly with income, and several less developed countries, particularly in Latin America, outperformed more developed nations (notably in Eastern and Southern Europe). In the sub-group analysis, the presence of official public health authority vaccination recommendations did not correlate well with higher vaccine supply (positive:negative correlation=1.3:1), while reimbursement (4.5:1) and the use of wide-scale communication activities (5.3:1) correlated more strongly than development status (2.7:1). This study shows that globally vaccination levels remain low, and official vaccination recommendations alone are insufficient to drive higher coverage. Rather, policy measures that directly impact patients (i.e. reimbursement and communication) appear more effective, irrespective of countries' development status, and therefore may do more to help protect local populations against influenza.

Risk factors for pandemic (H1N1) 2009 seroconversion among adults, Singapore, 2009

A total of 828 community-dwelling adults were studied during the course of the pandemic (H1N1) 2009 outbreak in Singapore during June-September 2009. Baseline blood samples were obtained before the outbreak, and 2 additional samples were obtained during follow-up. Seroconversion was defined as a >4-fold increase in antibody titers to pandemic (H1N1) 2009, determined by using hemagglutination inhibition. Men were more likely than women to seroconvert (mean adjusted hazards ratio [HR] 2.23, mean 95% confidence interval [CI] 1.26-3.93); Malays were more likely than Chinese to seroconvert (HR 2.67, 95% CI 1.04-6.91). Travel outside Singapore during the study period was associated with seroconversion (HR 1.76, 95% CI 1.11-2.78) as was use of public transport (HR 1.81, 95% CI 1.05-3.09). High baseline antibody titers were associated with reduced seroconversion. This study suggests possible areas for intervention to reduce transmission during future influenza outbreaks.

Mitigating effects of vaccination on influenza outbreaks given constraints in stockpile size and daily administration capacity

Background

Influenza viruses are a major cause of morbidity and mortality worldwide. Vaccination remains a powerful tool for preventing or mitigating influenza outbreaks. Yet, vaccine supplies and daily administration capacities are limited, even in developed countries. Understanding how such constraints can alter the mitigating effects of vaccination is a crucial part of influenza preparedness plans. Mathematical models provide tools for government and medical officials to assess the impact of different vaccination strategies and plan accordingly. However, many existing models of vaccination employ several questionable assumptions, including a rate of vaccination proportional to the population at each point in time.

Methods

We present a SIR-like model that explicitly takes into account vaccine supply and the number of vaccines administered per day and places data-informed limits on these parameters. We refer to this as the non-proportional model of vaccination and compare it to the proportional scheme typically found in the literature.

Results

The proportional and non-proportional models behave similarly for a few different vaccination scenarios. However, there are parameter regimes involving the vaccination campaign duration and daily supply limit for which the non-proportional model predicts smaller epidemics that peak later, but may last longer, than those of the proportional model. We also use the non-proportional model to predict the mitigating effects of variably timed vaccination campaigns for different levels of vaccination coverage, using specific constraints on daily administration capacity.

Conclusions

The non-proportional model of vaccination is a theoretical improvement that provides more accurate predictions of the mitigating effects of vaccination on influenza outbreaks than the proportional model. In addition, parameters such as vaccine supply and daily administration limit can be easily adjusted to simulate conditions in developed and developing nations with a wide variety of financial and medical resources. Finally, the model can be used by government and medical officials to create customized pandemic preparedness plans based on the supply and administration constraints of specific communities.

Influenza vaccination coverage among high-risk groups in 11 European countries

BACKGROUND

National vaccination coverage rates for individuals at increased risk of influenza-related complications represent a useful public health indicator of preparedness. We compared European countries regarding (i) vaccination coverage among high-risk groups and (ii) the likelihood that high-risk individuals reported influenza vaccination compared with those at lower risk.

METHODS

We used data from the Survey of Health, Ageing and Retirement in Europe (SHARE) collected in 2004-05. Adults aged ≥ 50 years from 11 countries provided self-reports of an influenza vaccination in the previous year (n = 16,913). We defined four high-risk groups (age ≥ 65 years, presence of vascular disease, chronic lung disease or diabetes) and calculated vaccination coverage with 95% confidence intervals for each country. Country-specific multivariable logistic regression was used to estimate odds ratios (ORs) for membership in a high-risk group and vaccination.

RESULTS

The Netherlands had the highest influenza vaccination coverage in high-risk groups (≥ 75% in any group) while Greece had the lowest (<27% in any group). Older age was positively associated with report of vaccination in all countries, but the strength of this association varied from an OR of <2 (Germany) to >13 (The Netherlands). The ORs for the chronic disease groups was ≥ 4 for The Netherlands and were considerably lower (and often not statistically significant) for the other countries.

CONCLUSION

Influenza vaccination coverage among high-risk groups varies considerably between European countries. Our findings highlight potential opportunities for reducing influenza-related complications through support for vaccination programs that target high-risk individuals more effectively.

Vaccination of health-care workers against influenza: our obligation to protect patients

Please cite this paper as: Maltezou and Tsakris. (2011) Vaccination of health‐care workers against influenza: our obligation to protect patients. Influenza and Other Respiratory Viruses 5(6), 382–388.

Nosocomial influenza poses a threat for specific groups of patients and is associated not only with the disruption of health‐care services but also excess costs. Although vaccination of health‐care workers (HCWs) has been recommended for almost three decades and constitutes the most convenient and effective means to prevent nosocomial transmission, vaccine uptake within this group remains unacceptably low worldwide. In regard to the pandemic influenza A H1N1, HCWs constitute a priority group for immunization. Nevertheless, low vaccination rates have been documented regarding the influenza pandemic and associated with the onset of nosocomial cases and outbreaks. HCWs, health‐care institutions, and public health bodies have the moral obligation to protect vulnerable patients and therefore weigh the benefits of mandatory vaccination. Key effective interventions, such as the education of HCWs concerning the benefits and safety of influenza vaccination, the reinforcement of on‐site, free of charge vaccinations, and the use of mobile vaccination teams in conjunction with incentives, should be widely implemented.

Factors associated with influenza vaccination status of residents of a rural community in Japan

Background

The rate of influenza vaccination in Japan has declined over the past several decades. It is essential to identify community-specific factors that affect attitudes toward vaccination, but such parameters have not yet been fully determined in Japan. The present study used the Health Belief Model (HBM) to identify perceptions of influenza vaccination in a rural Japanese community.

Methods

All subjects were residents of a rural town in the southern part of Kyoto, Japan. An anonymous self-administered questionnaire was mailed to 846 randomly chosen households (containing 2,665 subjects). The survey explored gender, age, history of influenza, and factors associated with obtaining influenza vaccination, based on the HBM.

Results

A total of 1,182 valid responses (response rate, 44.4%) were received. Sources of information that were associated with vaccination decisions were medical facilities for children (OR = 4.21; 95% CI: 1.17-15.1), workplaces for adults (OR = 2.40; 95% CI: 1.22-4.75), medical facilities, town office and family for elderly subjects (OR = 6.18; 95% CI: 2.42-15.7, OR = 5.59; 95% CI: 2.26-13.8 and OR = 3.29; 95%CI: 1.01-10.6). Subjects, in all age groups, who strongly agreed that the vaccine was effective were significantly more likely to be vaccinated (OR = 10.5; 95%CI: 2.68-41.7 for children; OR = 8.85; 95%CI: 4.61-16.9 for adults; OR = 19.9; 95%CI: 8.28-48.0 for the elderly). The vaccination rate of elderly subjects who expressed concerns regarding adverse vaccine effects (OR = 0.34, 95% CI: 0.15-0.78) or who were worried about practical barriers to the vaccination process (OR = 0.13; 95% CI: 0.05-0.31) was significantly lower than in other populations.

Conclusions

Our results indicate that vaccination coverage can be increased if accurate information on personal risk, severity of influenza illness, and efficacy of vaccination are provided by responsible information sources that are easily accessible. Such sources include medical facilities and municipal offices. In addition, barriers and inconveniences associated with vaccination should be removed, especially if they impact on elderly people.

Parental perspectives on influenza vaccination in children with asthma

BACKGROUND

Influenza is an important cause of epidemic and pandemic disease leading to mortality and morbidity in children. Despite great efforts to increase influenza vaccination, many children with chronic medical conditions do not receive influenza vaccine. Our aim was to identify the demographic factors and asthma-associated characteristics related to vaccination, caregivers' attitudes and knowledge about influenza disease during the 2007-2008 influenza season.

METHODS

Caregivers of children with asthma were surveyed via a self-administered questionnaire to document their knowledge about influenza disease and vaccine and factors influencing vaccination.

RESULTS

We enrolled 311 children with asthma. The rate of lifetime influenza vaccination was 69.5%, whereas 51.8% of the patients had been vaccinated in the current season. There were no significant differences in demographic factors and asthma control parameters between the groups who received or did not receive influenza vaccine. Most of the parents whose children were vaccinated believed that influenza vaccination would decrease the prevalence and severity of asthma attacks (P < 0.05). The most important reason cited by parents for deciding on the influenza vaccine for their child was physician recommendation (80.1%). The major reasons for declining the vaccination were unawareness that the influenza vaccine was a requirement for their child (29.3%) and illness at the time of vaccination (20%).

CONCLUSION

Physician recommendation is important in the influenza vaccination decision. Demographic factors and asthma control parameters had no influence on immunization uptake but parental beliefs and attitudes could be determinant. Greater effort is needed to increase influenza vaccination rates, in children with asthma.