Efficacy and effectiveness of influenza vaccination

Implementation of a Military Emergency Department Influenza Vaccination Program: Lessons from Failure

INTRODUCTION

Influenza infection in the United States results in hundreds of thousands of hospitalizations and 12,000 to 60,000 yearly deaths. Influenza season sees a sharp increase in emergency department (ED) patients nationwide, as primary care offices become overwhelmed. Because the ED is unique in its reach of underserved communities, ED vaccination programs can help maximize the number of people protected by vaccination. Influenza vaccination is one of the only vaccines that occurs yearly; therefore, successes with ED distribution of the influenza vaccine can potentially be translated into efforts of vaccinating the U.S. population more efficiently against other viral illnesses, such COVID-19. There has also not been a previous description in the literature of a vaccination program being used in a military setting. The original purpose of this study was to measure the effect of an ED vaccination program on our vaccine penetration and ED length of stay as well as to analyze the impact of provider education on vaccine uptake on vaccine refusal.

METHODS

This was an observational, quality improvement project in the Wright-Patterson Medical Center Emergency Department evaluating an influenza vaccination program set to last from October 1, 2020 to April 1, 2021. Patients were to be surveyed to assess prior vaccination status, identify those at high risk for influenza complications, and to measure the effects of point-of-care education on vaccine acceptance. Separate measurements included average ED length of stay and the study's impact on how quickly the base population could be vaccinated.

RESULTS

The effort was determined no longer feasible on November 20, 2020 because of the significant barriers. Although no data were gathered, we were able to glean important information that is vital in future efforts to implement ED-based vaccination programs. Reasons for program failure were multi-factorial, but were mainly attributed to rapid implementation, issues with Pyxis ordering and vaccine shipments, and vaccine storage capacity. The program also lacked a multidisciplinary implementation team of nurses and technicians, which could have better anticipated critical barriers.

CONCLUSION

Influenza has caused multiple worldwide pandemics, contributed to countless deaths, and continues to be a challenge. ED-based influenza vaccination programs have been trialed to augment the primary care system in their effort to prevent deaths from influenza. The literature has shown that these programs are cost-effective and efficacious, but significant barriers have stunted their widespread utilization. Examining the rapid implementation and failure of this program highlights the importance of implementation models, process and barrier mapping, and proper operationalization. It is also the first such program that has been trialed in a military treatment facility. In consideration of the recent pandemic, successful ED-based vaccination programs can also offer a model for additional dissemination of other vaccines, such as the COVID-19 vaccine.

Association of influenza vaccination or influenza virus infection history with subsequent infection risk among children: The Japan Environment and Children's Study (JECS)

We measured the association between history of influenza vaccination by age 2 years and influenza virus (IFV) infection at ages 3 and 4 years by relative risk reduction. We also examined the association between history of IFV infection by age 2 years and recurrent IFV infection at age 3 years. This study included 73,666 children from a large Japanese birth cohort. Among children vaccinated never, once or twice when aged under 2 years, 16.0%, 10.8% and 11.3%, respectively, had been infected with IFV by age 3 years, and 19.2%, 14.5% and 16.0%, respectively, by age 4 years. Compared with no history of influenza vaccination, vaccination at ages 1 and/or 2 years reduced the risk of IFV infection at age 3 by 30%-32% and at age 4 by 17%-24%. The relative risk of recurrent IFV infection at ages 3 and 4 years increased in proportion to the number of prior infections by age 2. One-season-prior influenza vaccination history reduced the IFV infection risk at age 3 years by 25%-42%. Influenza vaccination most effectively protected children at age 3 who lacked older sibling(s) and did not attend nursery school. One-season-prior IFV infection increased the relative risk of recurrent infection at age 3 years (1.72-3.33). In conclusion, influenza vaccination-induced protection may partly extend to the next season. Owing to the relative risk reduction by influenza vaccination and the increased relative risk of IFV infection from prior-season infection, annual influenza vaccination is recommended.

Knowledge, Attitudes, and Practices of Influenza Vaccination among Parents of Children with Asthma: A Cross-Sectional Study

Asthma is the most common chronic disease in childhood. Exacerbation is a significant problem for asthmatic patients, and viral infections remain the most frequent triggers of asthma exacerbations. This study explored knowledge, attitudes, and practices (KAP) of parents of asthmatic children towards providing influenza vaccine to their children. This cross-sectional study enrolled parents of asthmatic children who visited the outpatient respiratory clinics of two Jordanian hospitals. The present study enrolled 667 parents of asthmatic children (62.8% female). The median age of the participants' children was 7 years. The results showed that 60.4% of the children with asthma never received a flu vaccine. Most of those who had received the flu vaccine reported that the side effects were mild (62.7%). Asthma duration was positively and significantly associated with increased vaccine hesitancy/rejection (OR = 1.093, 95% CI = (1.004-1.190), p = 0.04; and OR = 1.092, 95% CI = (1.002-1.189), p = 0.044, respectively). As the attitude towards flu vaccine score increases, odds of vaccination hesitancy/rejection decreased (OR = 0.735, 95% CI = (0.676-0.800), p < 0.001; and OR = 0.571, 95% CI = (0.514-0.634), p < 0.001, respectively). The main reasons for vaccination hesitancy/refusal included "I don't think my child needs it" (22.3%) followed by "I forget it" (19.5%). The rate of vaccination among children was low and emphasized the necessity of encouraging parents with asthmatic children to vaccinate their children by conducting health awareness campaigns and also emphasized the role of doctors and other healthcare professionals.

Seasonal influenza vaccination expands hemagglutinin-specific antibody breadth to older and future A/H3N2 viruses

History of influenza A/H3N2 exposure, especially childhood infection, shape antibody responses after influenza vaccination and infection, but have not been extensively studied. We investigated the breadth and durability of influenza A/H3N2-specific hemagglutinin-inhibition antibodies after live-attenuated influenza vaccine in children (aged 3-17 years, n = 42), and after inactivated influenza vaccine or infection in adults (aged 22-61 years, n = 42) using 14 antigenically distinct A/H3N2 viruses circulating from 1968 to 2018. We found that vaccination and infection elicited cross-reactive antibody responses, predominantly directed against newer or future strains. Childhood H3-priming increased the breadth and magnitude of back-boosted A/H3N2-specific antibodies in adults. Broader and more durable A/H3N2-specific antibodies were observed in repeatedly vaccinated adults than in children and previously unvaccinated adults. Our findings suggest that early A/H3N2 exposure and frequent seasonal vaccination could increase the breadth and seropositivity of antibody responses, which may improve vaccine protection against future viruses.

Serum anti-neuraminidase antibody responses in human influenza A(H1N1)pdm09 virus infections

Haemagglutination inhibition (HAI) antibody titres are a correlate of protection for influenza virus infection, but several studies have also demonstrated the protective role of anti-neuraminidase (anti-NA) antibodies. However, there is limited data on anti-NA antibody responses in naturally occurring human influenza. We investigated anti-NA antibody responses to pandemic N1 and seasonal N1 in 18 RT-PCR-confirmed patients with naturally acquired pandemic influenza A (H1N1) 2009 disease detected as part of a prospective community study of influenza. There were increases in neuraminidase inhibition (NAI) antibody titres to both pandemic and seasonal N1 antigens, with greater fold increases in those who had low levels of anti-pandemic N1 titres in acute sera. Of 18 patients with pandemic H1N1 infection, fourfold increases in antibody were observed by HAI in 11 (61%) patients, by anti-pandemic N1 inhibition in 13 (72%) or either in 15 of them (83%). Prior seasonal H1N1 virus infections had elicited cross-reactive anti-pandemic N1 antibody titres in some people prior to the emergence of the 2009 pandemic H1N1 virus. Antibody responses to the anti-N1 pandemic 2009 virus and cross-reactive responses to anti-seasonal N1 antibody were seen in influenza A pandemic 2009 infections. NAI antibodies can complement HAI antibody in sero-diagnosis and sero-epidemiology.

Influenza Infection in Humans Induces Broadly Cross-Reactive and Protective Neuraminidase-Reactive Antibodies

Antibodies to the hemagglutinin (HA) and neuraminidase (NA) glycoproteins are the major mediators of protection against influenza virus infection. Here, we report that current influenza vaccines poorly display key NA epitopes and rarely induce NA-reactive B cells. Conversely, influenza virus infection induces NA-reactive B cells at a frequency that approaches (H1N1) or exceeds (H3N2) that of HA-reactive B cells. NA-reactive antibodies display broad binding activity spanning the entire history of influenza A virus circulation in humans, including the original pandemic strains of both H1N1 and H3N2 subtypes. The antibodies robustly inhibit the enzymatic activity of NA, including oseltamivir-resistant variants, and provide robust prophylactic protection, including against avian H5N1 viruses, in vivo. When used therapeutically, NA-reactive antibodies protected mice from lethal influenza virus challenge even 48 hr post infection. These findings strongly suggest that influenza vaccines should be optimized to improve targeting of NA for durable and broad protection against divergent influenza strains.

Vaccines for preventing influenza in the elderly

BACKGROUND

The consequences of influenza in the elderly (those age 65 years or older) are complications, hospitalisations, and death. The primary goal of influenza vaccination in the elderly is to reduce the risk of death among people who are most vulnerable. This is an update of a review published in 2010. Future updates of this review will be made only when new trials or vaccines become available. Observational data included in previous versions of the review have been retained for historical reasons but have not been updated because of their lack of influence on the review conclusions.

OBJECTIVES

To assess the effects (efficacy, effectiveness, and harm) of vaccines against influenza in the elderly.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 11), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (1966 to 31 December 2016); Embase (1974 to 31 December 2016); Web of Science (1974 to 31 December 2016); CINAHL (1981 to 31 December 2016); LILACS (1982 to 31 December 2016); WHO International Clinical Trials Registry Platform (ICTRP; 1 July 2017); and ClinicalTrials.gov (1 July 2017).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs assessing efficacy against influenza (laboratory-confirmed cases) or effectiveness against influenza-like illness (ILI) or safety. We considered any influenza vaccine given independently, in any dose, preparation, or time schedule, compared with placebo or with no intervention. Previous versions of this review included 67 cohort and case-control studies. The searches for these trial designs are no longer updated.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed risk of bias and extracted data. We rated the certainty of evidence with GRADE for the key outcomes of influenza, ILI, complications (hospitalisation, pneumonia), and adverse events. We have presented aggregate control group risks to illustrate the effect in absolute terms. We used them as the basis for calculating the number needed to vaccinate to prevent one case of each event for influenza and ILI outcomes.

MAIN RESULTS

We identified eight RCTs (over 5000 participants), of which four assessed harms. The studies were conducted in community and residential care settings in Europe and the USA between 1965 and 2000. Risk of bias reduced our certainty in the findings for influenza and ILI, but not for other outcomes.Older adults receiving the influenza vaccine may experience less influenza over a single season compared with placebo, from 6% to 2.4% (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.27 to 0.66; low-certainty evidence). We rated the evidence as low certainty due to uncertainty over how influenza was diagnosed. Older adults probably experience less ILI compared with those who do not receive a vaccination over the course of a single influenza season (3.5% versus 6%; RR 0.59, 95% CI 0.47 to 0.73; moderate-certainty evidence). These results indicate that 30 people would need to be vaccinated to prevent one person experiencing influenza, and 42 would need to be vaccinated to prevent one person having an ILI.The study providing data for mortality and pneumonia was underpowered to detect differences in these outcomes. There were 3 deaths from 522 participants in the vaccination arm and 1 death from 177 participants in the placebo arm, providing very low-certainty evidence for the effect on mortality (RR 1.02, 95% CI 0.11 to 9.72). No cases of pneumonia occurred in one study that reported this outcome (very low-certainty evidence). No data on hospitalisations were reported. Confidence intervaIs around the effect of vaccines on fever and nausea were wide, and we do not have enough information about these harms in older people (fever: 1.6% with placebo compared with 2.5% after vaccination (RR 1.57, 0.92 to 2.71; moderate-certainty evidence)); nausea (2.4% with placebo compared with 4.2% after vaccination (RR 1.75, 95% CI 0.74 to 4.12; low-certainty evidence)).

AUTHORS' CONCLUSIONS

Older adults receiving the influenza vaccine may have a lower risk of influenza (from 6% to 2.4%), and probably have a lower risk of ILI compared with those who do not receive a vaccination over the course of a single influenza season (from 6% to 3.5%). We are uncertain how big a difference these vaccines will make across different seasons. Very few deaths occurred, and no data on hospitalisation were reported. No cases of pneumonia occurred in one study that reported this outcome. We do not have enough information to assess harms relating to fever and nausea in this population.The evidence for a lower risk of influenza and ILI with vaccination is limited by biases in the design or conduct of the studies. Lack of detail regarding the methods used to confirm the diagnosis of influenza limits the applicability of this result. The available evidence relating to complications is of poor quality, insufficient, or old and provides no clear guidance for public health regarding the safety, efficacy, or effectiveness of influenza vaccines for people aged 65 years or older. Society should invest in research on a new generation of influenza vaccines for the elderly.

Circulation of Influenza Virus in the 2015/2016 Epidemic Season in Poland: Serological Evaluation of Anti-hemagglutinin Antibodies

The diagnostic of influenza virus infections is possible using molecular biology methods as well as the analysis of anti-hemagglutinin (anti-HA) antibodies in the blood serum. The aim of this study was to determine the level of anti-HA antibodies in 7 age groups of patients during the 2015/2016 epidemic season in Poland. A total of 1050 serum samples were tested using the hemagglutination inhibition (HAI) assay. We confirmed the presence of anti-HA antibodies for the influenza virus strains: A/California/7/2009(H1N1)pdm09, A/Switzerland/9715293/2013(H3N2), and B/Phuket/3073/2013, which were the components of the influenza vaccine for the 2015/2016 epidemic season. The level of specific anti-HA antibodies was different in each age group. The geometric mean titers were highest at age 5-9 years, where the antibody protection level reached 61.3% against B/Phuket/3073/2013 and 52.7% for A/Switzerland/9715293/2013(H3N2) antigen. The antibody level amounted to 56.7% against for antigen B at age 45-64. In the remaining age groups, the protection levels for all hemagglutinin types did not exceed 50%. These findings confirm the urgent need to increase a persistently low influenza vaccination coverage in the Polish population, which may have had its part in the noticeable increase in the confirmed cases of influenza and influenza-like virus infection during the season.

Excess pneumonia and influenza hospitalizations associated with influenza epidemics in Portugal from season 1998/1999 to 2014/2015

BACKGROUND

The aim of this study was to estimate excess pneumonia and influenza (P&I) hospitalizations during influenza epidemics and measure their correlation with influenza vaccine coverage in the 65 and more years old, according to the type/subtype of influenza virus.

METHODS

The study period comprised week 40/1998-40/2015. Age-specific weekly P&I hospitalizations (ICD-9: 480-487) as main diagnosis were extracted from the National Hospital Discharge database. Age-specific baseline hospitalization rates were estimated by autoregressive integrated moving average (ARIMA) model without time periods with excess hospitalizations. Excess hospitalizations were calculated by subtracting expected hospitalization rates from the observed during influenza epidemic periods. Correlation between excess P&I hospitalizations and influenza vaccine coverage in the elderly was measured with Pearson correlation coefficient.

RESULTS

The average excess P&I hospitalizations/season was 19.4/105 (range 0-46.1/105 ), and higher excess was observed in young children with <2 years (79.8/105 ) and ≥65 years (68.3/105 ). In epidemics with A(H3) dominant, the highest excess hospitalizations were observed among 65 and over. Seasons which influenza B or A(H1)pdm09 dominance the highest excess was observed in children with <2 years. High negative correlation was estimated between excess hospitalizations associated with A(H3) circulation and vaccine coverage in the elderly (r = -.653; 95% CI: -0.950 to -0.137).

CONCLUSION

Over 80% of the influenza epidemics were associated with excess hospitalizations. However, excess P&I hospitalizations pattern differed from age group and circulating virus. This ecologic approach also identified a reduction in excess P&I associated with A(H3) circulation with increasing vaccine coverage in the elderly.

Low-Cost Intervention to Increase Influenza Vaccination Rate at a Comprehensive Cancer Center

Influenza morbidity and mortality can be severe and costly. Vaccination rates remain suboptimal in cancer patients due to provider- and patient-related factors. The objective of this study was to evaluate whether low-cost provider- and patient-focused interventions would increase influenza vaccination rates at the University of Michigan Comprehensive Cancer Center (UMCCC). This quality improvement project included all patients without documentation of influenza vaccination prior to their first outpatient appointment during the 2011-2012 and 2012-2013 influenza seasons. The multi-stepped intervention included provider and patient reminders. Influenza vaccination rates were compiled using CPT-4 codes. Same-day (with appointment) vaccination rates during the intervention seasons were compared to historical (2005-2011 seasons) controls; vaccination rates were also compared to contemporary control population at the University of Michigan Health System (UMHS). Reasons for non-adherence with vaccination were explored. The cumulative same-day vaccination rate in eligible adults was 10.1 % (2011-2012) and 9.4 % (2012-2013) compared to an average 6.9 % during influenza seasons 2005-2011. Based on logistic regression analysis, there was a 37.6 % (95 % CI 35-40.3 %) and 56.1 % (95 % CI 40.9-73 %) relative increase in the adult vaccination rate associated with the intervention, with 399 and 697 additional vaccinations, respectively, for each season. During the 2012-2013 season, the UMCCC adult vaccination rate was higher compared to the remainder of that of the UMHS. The intervention was well accepted by providers. Reasons for no vaccination were provider- and patient-related. Increasing provider and patient awareness with a simple, inexpensive intervention was associated with higher influenza vaccination rates at a large academic cancer center. The intervention is permanently implemented during influenza seasons.

Economic benefits of sharing and redistributing influenza vaccines when shortages occurred

Background

Recurrent influenza outbreak has been a concern for government health institutions in Taiwan. Over 10% of the population is infected by influenza viruses every year, and the infection has caused losses to both health and the economy. Approximately three million free vaccine doses are ordered and administered to high-risk populations at the beginning of flu season to control the disease. The government recommends sharing and redistributing vaccine inventories when shortages occur. While this policy intends to increase inventory flexibility, and has been proven as widely valuable, its impact on vaccine availability has not been previously reported.

Material and methods

This study developed an inventory model adapted to vaccination protocols to evaluate government recommended polices under different levels of vaccine production. Demands were uncertain and stratified by ages and locations according to the demographic data in Taiwan.

Results

When vaccine supply is sufficient, sharing pediatric vaccine reduced vaccine unavailability by 43% and overstock by 54%, and sharing adult vaccine reduced vaccine unavailability by 9% and overstock by 15%. Redistributing vaccines obtained greater gains for both pediatrics and adults (by 75%). When the vaccine supply is in short, only sharing pediatric vaccine yielded a 48% reduction of unused inventory, while other polices do not improve performances.

Conclusions

When implementing vaccination activities for seasonal influenza intervention, it is important to consider mismatches of demand and vaccine inventory. Our model confirmed that sharing and redistributing vaccines can substantially increase availability and reduce unused vaccines.

Circulation of Antibodies Against Influenza Virus Hemagglutinins in the 2014/2015 Epidemic Season in Poland

The aim of this study was to determine the level of anti-hemagglutinin antibodies in the serum of people in different age-groups during the 2014/2015 epidemic influenza season in Poland. A total of 1050 sera were tested. The level of anti-hemagglutinin antibodies was determined using the hemagglutinin inhibition test. The results provided information on the incidence of circulating A/California/7/2009(H1N1)pdm09, A/Texas/50/2012(H3N2), and B/Massachusetts/2/2012 viruses. The level of antibodies against influenza differed between age-groups. The protection rate was the highest for the antigen B/Massachusetts/2/2012, with the decreasing order of values in the following age-groups: ≥65 years (76.7 %), 15-25 years (72.7 %), and 0-4 years (62.0 %). The average values of the protection rate in other age-groups were as follows: 43.3 % in 22-64 years, 40% in 5-9 years, and 39.3 % in 45-64 years of age, while the lowest value of 22.7 % was in 10-14 years old subjects. In the 2014/2015 epidemic season in Poland only were 3.6 % of the population vaccinated. That is why the presented results could be interpreted as a response of the immune system of patients after infection caused by influenza virus.

Determinants of influenza vaccination in older adults: A nationwide community-based study in Taiwan

AIMS

Influenza vaccination (InVa) is an effective measure for preventing influenza infection, which is a major cause of morbidity and mortality in older adults. However, the determinants of InVa remain unclear.

METHODS

The present study included 4756 adults aged 55 years and older who completed the baseline examination of the Healthy Aging Longitudinal Study in Taiwan. During the examination, each participant received assessments of InVa status. Comprehensive assessments of sociodemographic (age, sex, education level, marital status, living alone and occupation) and health-related factors (chronic diseases, smoking status, alcohol intake, physical activities, cognitive status and physical performance) were also carried out. The InVa rate was defined as the number of participants who reported receiving free InVa divided by the total number of candidates for free InVa. Multinomial logistic regression analysis was applied to investigate the sociodemographic and health-related determinants of InVa status.

RESULTS

The coverage rate of InVa was 44.8% (2130/4756). Older age (adjusted odds ratio [OR; >75 years vs <65 years] 7.72, 95% CI 6.26-9.52), multiple chronic diseases (OR [≥2 vs 0)] 1.31, 95% CI 1.10-1.65) and physical activity (OR [yes vs no] 1.43, 95% CI 1.23-1.64) were positively associated with receiving InVa. A current smoking status (OR 0.67, 95% CI 0.55-0.82) was negatively associated with receiving InVa.

CONCLUSIONS

Older adults who received InVa differed from non-receivers in multiple sociodemographic and health-related characteristics. These findings support continual efforts to improve the InVa coverage rate in vulnerable populations. Geriatr Gerontol Int 2017; 17: 2396-2402.

Recommended immunization schedules for adults: Clinical practice guidelines by the Escmid Vaccine Study Group (EVASG), European Geriatric Medicine Society (EUGMS) and the World Association for Infectious Diseases and Immunological Disorders (WAidid)

Rapid population aging has become a major challenge in the industrialized world and progressive aging is a key reason for making improvement in vaccination a cornerstone of public health strategy. An increase in age-related disorders and conditions is likely to be seen in the near future, and these are risk factors for the occurrence of a number of vaccine-preventable diseases. An improvement in infectious diseases prevention specifically aimed at adults and the elderly can therefore also decrease the burden of these chronic conditions by reducing morbidity, disability, hospital admissions, health costs, mortality rates and, perhaps most importantly, by improving the quality of life. Among adults, it is necessary to identify groups at increased risk of vaccine-preventable diseases and highlight the epidemiological impact and benefits of vaccinations using an evidence-based approach. This document provides clinical practice guidance on immunization for adults in order to provide recommendations for decision makers and healthcare workers in Europe. Although immunization is considered one of the most impactful and cost-effective public health measures that can be undertaken, vaccination coverage rates among adults are largely lower than the stated goal of ≥ 95% among adults, and stronger efforts are needed to increase coverage in this population. Active surveillance of adult vaccine-preventable diseases, determining the effectiveness of the vaccines approved for marketing in the last 5 y, the efficacy and safety of vaccines in immunocompromised patients, as well as in pregnant women, represent the priorities for future research.

Protecting our patients by protecting ourselves: An analysis of the personal influenza immunization rate of Ontario community pharmacists

BACKGROUND

With recent expansions to scope of practice that have allowed Canadian pharmacists to play a larger role in administering influenza vaccinations to the public, it is important that pharmacists themselves meet Canadian guidelines recommending that 80% of health care professionals and 100% of vaccinators receive an annual influenza vaccination. Unvaccinated health care professionals pose an infection risk to patients they serve and are at an increased risk of infection themselves.

METHODS

An online, anonymous survey was sent to Ontario community pharmacists to determine whether they had received the influenza vaccination during the 2013-2014 influenza season. All significant univariate chi-square analysis respondent characteristics were included in a multivariate regression analysis model to determine predictors of vaccination status.

RESULTS

A total of 780 pharmacists completed the survey (18.1% response rate), which showed that 7 in 10 Ontario community pharmacists received the influenza vaccine. Those certified to immunize were nearly 3 times more likely to have received the influenza vaccine than those not certified (81.6% versus 61.2%, respectively).

DISCUSSION

Having 70% of Ontario community pharmacists vaccinated against influenza is both an accomplishment and an opportunity to improve vaccination rates. While similar to the influenza immunization rates of other health care professions, Ontario community pharmacists did not meet Public Health Canada's recommendations. Comprehensive worksite programs, including promotion, education and convenient access to influenza vaccination at no cost, could increase community pharmacist influenza vaccination rates.

CONCLUSION

The authors issue a call to arms to encourage all pharmacists to receive the influenza vaccine to protect the public and themselves.

Cost-effectiveness analysis of the direct and indirect impact of intranasal live attenuated influenza vaccination strategies in children: alternative country profiles

BACKGROUND

Influenza poses a significant burden on healthcare systems and society, with under-recognition in the paediatric population. Existing vaccination policies (largely) target the elderly and other risk groups where complications may arise.

OBJECTIVE

The goal of this study was to evaluate the cost-effectiveness of annual paediatric vaccination (in 2-17-year-olds) with live attenuated influenza vaccination (LAIV), as well as the protective effect on the wider population in England and Wales (base). The study aimed to demonstrate broad applications of the model in countries where epidemiological and transmission data is limited and that have sophisticated vaccination policies (Brazil, Spain, and Taiwan).

METHODS

The direct and indirect impact of LAIV in the paediatric cohort was simulated using an age-stratified dynamic transmission model over a 5-year time horizon of daily cycles and applying discounting of 3.5% in the base case. Pre-existing immunity structure was based on a 1-year model run. Sensitivity analyses were conducted.

RESULTS

In the base case for England and Wales, the annual paediatric strategy with LAIV was associated with improvements in influenza-related events and quality-adjusted life years (QALYs) lost, yielding an incremental cost per QALY of £6,208. The model was robust to change in the key input parameters. The probabilistic analysis demonstrated LAIV to be cost effective in more than 99% of iterations, assuming a willingness-to-pay threshold of £30,000. Incremental costs per QALY for Brazil were £2,817, and for the cases of Spain and Taiwan the proposed strategy was dominant over the current practice.

CONCLUSION

In addition to existing policies, annual paediatric vaccination using LAIV provides a cost-effective strategy that offers direct and indirect protection in the wider community. Paediatric vaccination strategies using LAIV demonstrated clinical and economic benefits over alternative (current vaccination) strategies in England and Wales as well as Brazil, Spain, and Taiwan.

Infants and the seasonal influenza vaccine. A global perspective on safety, effectiveness, and alternate forms of protection

Seasonal influenza is a substantial cause of severe illness among infants under 6 months of age globally. There are multiple methods of vaccination against influenza, including inactivated and live vaccines that are approved and recommended for children and adults over 6 months of age, but there is no vaccine that protects against seasonal influenza for children <6 months of age. This group is at a high risk of severe illness and is associated with higher rates of hospitalization and mortality during the influenza season. In absence of an available vaccine, approaches protecting young infants from influenza must be taken seriously. These methods include vaccinating pregnant women for influenza as a method of protecting mothers and the fetus as well as vaccinating caregivers and close contacts of individuals in this age group.

Evaluation of Antihemagglutinin and Antineuraminidase Antibodies as Correlates of Protection in an Influenza A/H1N1 Virus Healthy Human Challenge Model

Despite long-term investment, influenza continues to be a significant worldwide problem. The cornerstone of protection remains vaccination, and approved vaccines seek to elicit a hemagglutination inhibition (HAI) titer of ≥1:40 as the primary correlate of protection. However, recent poor vaccine performance raises questions regarding the protection afforded and whether other correlates of protection should be targeted. A healthy volunteer challenge study was performed with a wild-type 2009 A(H1N1)pdm influenza A challenge virus at the NIH Clinical Center to evaluate two groups of participants with HAI titers of ≥1:40 and <1:40. The primary objective was to determine whether participants with HAI titers of ≥1:40 were less likely to develop mild to moderate influenza disease (MMID) after intranasal inoculation. HAI titers of ≥1:40 were protective against MMID but did not reduce the incidence of symptoms alone. Although the baseline HAI titer correlated with some reduction in disease severity measures, overall, the baseline NAI titer correlated more significantly with all disease severity metrics and had a stronger independent effect on outcome. This study demonstrates the importance of examining other immunological correlates of protection rather than solely HAI titers. This challenge study confirms the importance of NAI titer as a correlate and for the first time establishes that it can be an independent predictor of reduction of all aspects of influenza disease. This suggests that NAI titer may play a more significant role than previously thought and that neuraminidase immunity should be considered when studying susceptibility after vaccination and as a critical target in future influenza vaccine platforms.

This study represents the first time the current gold standard for evaluating influenza vaccines as set by the U.S. Food and Drug Administration and the European Medicines Agency Committee for Medicinal Products for Human Use, a “protective” hemagglutination inhibition (HAI) titer of ≥1:40, has been evaluated in a well-controlled healthy volunteer challenge study since the cutoff was established. We used our established wild-type influenza A healthy volunteer human challenge model to evaluate how well this antibody titer predicts a reduction in influenza virus-induced disease. We demonstrate that although higher HAI titer is predictive of some protection, there is stronger evidence to suggest that neuraminidase inhibition (NAI) titer is more predictive of protection and reduced disease. This is the first time NAI titer has been clearly identified in a controlled trial of this type to be an independent predictor of a reduction in all aspects of influenza.

Viral Infections in Children in the 2014/2015 Epidemic Season in Poland

In every epidemic season, viral infections affect the general population, including children, which is an underestimated issue. The present study demonstrates the results of examination of 802 clinical samples obtained from pediatric patients aged 0-14 years during the 2014/2015 epidemic season in Poland. The study was part of the virological surveillance systems - SENTINEL and NON-SENTINEL. A positive result for virological infection was obtained in 50.9 % of samples tested. The distribution of positive results by the age-groups was as follows: 38.2 % in 0-4 years old, 8.5 % in 5-9 years old, and 4.2 % in 10-14 years old children. Influenza viruses accounted for 48.0 % and influenza-like viruses for 52.0 % of all positive samples. Concerning the influenza virus, molecular biology-based techniques confirmed the infection caused by influenza type A in 63.3 % of samples, consisting of unsubtyped A virus detected in 65.3 % of cases of this sample group, subtype A/H1N1/pdm09 in 28.2 %, and subtype A/H3N2/ in 6.5 %. Genetic material of influenza B was detected in 36.7 % of samples. In a group of influenza-like viruses, the predominant virus was respiratory syncytial virus (RSV) in as many as 96.2 % of samples, followed by parainfluenza viruses: PIV3 - 1.4 % and PIV1 - 1.0 %. Attention should be paid to the coinfection of respiratory viruses. There were six possible coinfection combinations reported in Poland, with four of them related to children up to 14 years old.

The free vaccination policy of influenza in Beijing, China: The vaccine coverage and its associated factors

BACKGROUND

In order to improve influenza vaccination coverage, the coverage rate and reasons for non-vaccination need to be determined. In 2007, the Beijing Government published a policy providing free influenza vaccinations to elderly people living in Beijing who are older than 60. This study examines the vaccination coverage after the policy was carried out and factors influencing vaccination among the elderly in Beijing.

METHODS

A cross-sectional survey was conducted through the use of questionnaires in 2013. A total of 1673 eligible participants were selected by multistage stratified random sampling in Beijing using anonymous questionnaires in-person. They were surveyed to determine vaccination status and social demographic information.

RESULTS

The influenza vaccination coverage was 38.7% among elderly people in Beijing in 2012. The most common reason for not being vaccinated was people thinking they did not need to have a flu shot. After controlling for age, gender, income, self-reported health status, and the acceptance of health promotion, the rate in rural areas was 2.566 (95% confidence interval [CI], 1.801-3.655, P<0.010) times greater than that in urban areas. Different mechanisms of health education and health promotion have different influences on vaccination uptake. Those whom received information through television, community boards, or doctors were more likely to get vaccinated compared to those who did not (Odds Ratio [OR]=1.403, P<0.010; OR=1.812, P<0.010; OR=2.647, P<0.010).

CONCLUSION

The influenza vaccine coverage in Beijing is much lower than that of developed countries with similar policies. The rural-urban disparity in coverage rate (64.1% versus 33.5%), may be explained by differing health provision systems and personal attitudes toward free services due to socioeconomic factors. Methods for increasing vaccination levels include increasing the focus on primary care and health education programs, particularly recommendations from doctors, to the distinct target populations, especially with a focus on expanding these efforts in urban areas.

Safety and immunogenicity of influenza whole inactivated virus vaccines: A phase I randomized clinical trial

BACKGROUND

Influenza vaccine production capacity is still insufficient to meet global demand in case of a pandemic. To expand worldwide influenza vaccine production capacity, a solid and transferable egg-based influenza vaccine production process was established that is suitable for upscaling and technology transfer to vaccine manufacturers in low- and middle-income countries. As a proof-of-concept, the safety and immunogenicity of a pandemic whole inactivated virus (WIV) vaccine (H5N1) and a monovalent seasonal WIV vaccine (H3N2) were evaluated in a phase I clinical trial in adults.

METHODS

Subjects were vaccinated with 2 doses of pandemic WIV vaccine (pWIV), or one dose of either seasonal WIV vaccine (sWIV) or a commercially available trivalent comparator vaccine followed by a placebo dose. Haemagglutination inhibiting antibody titres against the influenza strains were determined before and 21 d after each vaccination.

RESULTS

The frequency and severity of adverse reactions were comparable between groups. No serious adverse events were reported. After a single dose of sWIV the seroconversion rate was 91% (Committee for Proprietary Medicinal Products (CPMP) criterion >40%), the seroprotection rate was 100% (CPMP criterion >70%), and the mean geometric mean titre (GMT) increase was 24.9 (CPMP criterion >2.5). After two doses of pWIV, seroconversion rate and seroprotection rate were both 71%, and the mean GMT increase was 7.8.

CONCLUSIONS

Both pWIV and sWIV were equally well-tolerated as the comparator vaccine, and both vaccines complied with all 3 CPMP criteria. EudraCT 2011-000159-17. Netherlands National Trial Register 2695.

Cost-effectiveness analysis of antiviral treatment in the management of seasonal influenza A: point-of-care rapid test versus clinical judgment

Background

A point‐of‐care rapid test (POCRT) may help early and targeted use of antiviral drugs for the management of influenza A infection.

Objective

(i) To determine whether antiviral treatment based on a POCRT for influenza A is cost‐effective and, (ii) to determine the thresholds of key test parameters (sensitivity, specificity and cost) at which a POCRT based‐strategy appears to be cost effective.

Methods

An hybrid « susceptible, infected, recovered (SIR) » compartmental transmission and Markov decision analytic model was used to simulate the cost‐effectiveness of antiviral treatment based on a POCRT for influenza A in the social perspective. Data input parameters used were retrieved from peer‐review published studies and government databases. The outcome considered was the incremental cost per life‐year saved for one seasonal influenza season.

Results

In the base‐case analysis, the antiviral treatment based on POCRT saves 2 lives/100 000 person‐years and costs $7600 less than the empirical antiviral treatment based on clinical judgment alone, which demonstrates that the POCRT‐based strategy is dominant. In one and two way‐sensitivity analyses, results were sensitive to the POCRT accuracy and cost, to the vaccination coverage as well as to the prevalence of influenza A. In probabilistic sensitivity analyses, the POCRT strategy is cost‐effective in 66% of cases, for a commonly accepted threshold of $50 000 per life‐year saved.

Conclusion

The influenza antiviral treatment based on POCRT could be cost‐effective in specific conditions of performance, price and disease prevalence.

Increasing herd immunity with influenza revaccination

Seasonal influenza is a significant public health concern globally. While influenza vaccines are the single most effective intervention to reduce influenza morbidity and mortality, there is considerable debate surrounding the merits and consequences of repeated seasonal vaccination. Here, we describe a two-season influenza epidemic contact network model and use it to demonstrate that increasing the level of continuity in vaccination across seasons reduces the burden on public health. We show that revaccination reduces the influenza attack rate not only because it reduces the overall number of susceptible individuals, but also because it better protects highly connected individuals, who would otherwise make a disproportionately large contribution to influenza transmission. We also demonstrate that our results hold on an empirical contact network, in the presence of assortativity in vaccination status, and are robust for a range of vaccine coverage and efficacy levels. Our work contributes a population-level perspective to debates about the merits of repeated influenza vaccination and advocates for public health policy to incorporate individual vaccine histories.

A Novel Dynamic Model for Health Economic Analysis of Influenza Vaccination in the Elderly

Introduction

New vaccines are being developed to improve the efficacy of seasonal influenza immunization in elderly persons aged ≥65 years. These products require clinical and economic evaluation to aid policy decisions.

Methods

To address this need, a two-part model has been developed, which we have applied to examine the potential clinical and economic impact of vaccinating elderly persons with adjuvanted trivalent inactivated influenza vaccine (aTIV) relative to conventional trivalent (TIV) and quadrivalent (QIV) vaccines. We compared outcomes in the US population for (1) aTIV in persons aged ≥65 years and QIV in all other age cohorts; (2) QIV in all cohorts; (3) TIV in all cohorts. Low, average, and high intensity seasons with low, average, and high vaccine match scenarios were compared. Probabilistic sensitivity analysis was conducted within each discrete scenario to explore the impact of variation in model inputs on potential outcomes.

Results

Assuming current vaccination coverage rates in the US population with (a) 25% better efficacy of adjuvanted versus non-adjuvanted vaccine against any strain and (b) 35% better efficacy of non-adjuvanted vaccine against matched B versus mismatched B strains, use of aTIV in persons aged ≥65 years and QIV in persons <65 years could reduce influenza cases by 11,166–1,329,200, hospitalizations by 1365–43,674, and deaths by 421–11,320 versus use of QIV in all cohorts. These outcomes are reflected in a corresponding increase in quality-adjusted life-years (QALYs) of 3003–94,084. If the prevalence of mismatched influenza B was >54.5% of all circulating strains, use of QIV in all cohorts would offset the clinical benefits of aTIV. Elderly aTIV or QIV vaccination was associated with improved outcomes over non-adjuvanted TIV in many of the scenarios, particularly in low match seasons of any intensity. Total cost savings (including direct and indirect healthcare costs plus productivity impacts) with aTIV in the elderly versus QIV in the whole population ranged from $27 million (low intensity, low match) to $934 million (high intensity, high match). Univariate sensitivity analysis of relative vaccine prices in the average intensity, average match scenario indicated that aTIV could be marginally cost saving relative to QIV at the currently published Medicare price for influenza vaccines offering enhanced efficacy in the elderly. Elderly vaccination with aTIV was associated with a higher overall cost compared with TIV in only two scenarios (low intensity with average or high match); the incremental cost/QALY relative to TIV was $9980 in the average match scenario and $28,800 in the high match scenario.

Conclusions

Vaccination of persons aged ≥65 years with aTIV has the potential to provide clinical and economic benefit relative to QIV and TIV. The new model allows the assessment of various alternative strategies for available influenza vaccines.

Funding

Novartis Vaccines.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-015-0076-8) contains supplementary material, which is available to authorized users.

Self-recognition drives the preferential accumulation of promiscuous CD4(+) T-cells in aged mice

T-cell recognition of self and foreign peptide antigens presented in major histocompatibility complex molecules (pMHC) is essential for life-long immunity. How the ability of the CD4⁺ T-cell compartment to bind self- and foreign-pMHC changes over the lifespan remains a fundamental aspect of T-cell biology that is largely unexplored. We report that, while old mice (18–22 months) contain fewer CD4⁺ T-cells compared with adults (8–12 weeks), those that remain have a higher intrinsic affinity for self-pMHC, as measured by CD5 expression. Old mice also have more cells that bind individual or multiple distinct foreign-pMHCs, and the fold increase in pMHC-binding populations is directly related to their CD5 levels. These data demonstrate that the CD4⁺ T-cell compartment preferentially accumulates promiscuous constituents with age as a consequence of higher affinity T-cell receptor interactions with self-pMHC.

DOI:http://dx.doi.org/10.7554/eLife.05949.001

The immune system's T cells help the body to recognize and destroy harmful pathogens, such as viruses and bacteria. T cells ‘remember’ immunity-inducing fragments, called antigens, from the pathogens they have encountered. This memory then allows the immune system to quickly fend off infections if those pathogens, or even related pathogens, invade again. Vaccines exploit the ability to form immunological memory by exposing the body to harmless forms of the pathogen, or even just particular antigens from it. This allows the T cells to learn how to identify the pathogen without any risk of illness.

Vaccines have been extremely successful and have helped to virtually eliminate some diseases. However, for reasons that are unclear, the immune systems of older adults become less functional, so vaccines often lose their effectiveness. Paradoxically, as people age T cells become more likely to attack the body's cells, causing autoimmune diseases like arthritis. Understanding what happens to aging T cells to cause these immune changes may help scientists design vaccines that remain effective as people age.

Little is known about what happens to a particular type of T cell—the CD4⁺ T cells—as people age, even though this population plays a critical role in providing other immune cells with detailed instructions on when and how to fight a pathogen. Now, Deshpande et al. show that CD4⁺ T cells undergo a remarkable set of changes in aging mice. Mice that are nearing the end of their natural lifespan have fewer CD4⁺ T cells than younger mice. However, those CD4⁺ T cells that remain are more likely than CD4⁺ T cells from younger mice to be able to recognize multiple antigens. This increase in the proportion of multitasking CD4⁺ T cells corresponds with an increased tendency of these cells to bind to the body's own cells. If similar changes occur in older people, this may help explain some age-related autoimmune diseases. Yet, the relationship between the increase in multitasking CD4⁺ T cells and the decrease in immune function with aging remains to be fully explored.

The challenge for scientists now is to determine how these age-related changes in CD4⁺ T cells affect immune responses to vaccines or pathogens in older individuals. One implication of this work is that CD4⁺ T cell responses may be too robust and out of balance with other arms of the immune system. This could even lead to conditions such as autoimmunity. Alternatively, while there may be more CD4⁺ T cells that can multitask by recognizing multiple antigens, their ability to respond appropriately to infections or vaccinations may be diminished. What is clear from the work of Deshpande et al. is that the rules that have been defined for immunity in adults change with aging. The rules that govern immunity in the elderly must be more clearly defined to realize the goal of designing immunotherapies, such as vaccines, that provide protection throughout the lifespan.

DOI:http://dx.doi.org/10.7554/eLife.05949.002

Respiratory Infections in the U.S. Military: Recent Experience and Control

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.

Construction and Immunogenicity Evaluation of Recombinant Influenza A Viruses Containing Chimeric Hemagglutinin Genes Derived from Genetically Divergent Influenza A H1N1 Subtype Viruses

BACKGROUND AND OBJECTIVES

Influenza A viruses cause highly contagious diseases in a variety of hosts, including humans and pigs. To develop a vaccine that can be broadly effective against genetically divergent strains of the virus, in this study we employed molecular breeding (DNA shuffling) technology to create a panel of chimeric HA genes.

METHODS AND RESULTS

Each chimeric HA gene contained genetic elements from parental swine influenza A viruses that had a history of zoonotic transmission, and also from a 2009 pandemic virus. Each parental virus represents a major phylogenetic clade of influenza A H1N1 viruses. Nine shuffled HA constructs were initially screened for immunogenicity in mice by DNA immunization, and one chimeric HA (HA-129) was expressed on both a A/Puerto Rico/8/34 backbone with mutations associated with a live, attenuated phenotype (PR8LAIV-129) and a A/swine/Texas/4199-2/98 backbone (TX98-129). When delivered to mice, the PR8LAIV-129 induced antibodies against all four parental viruses, which was similar to the breadth of immunity observed when HA-129 was delivered as a DNA vaccine. This chimeric HA was then tested as a candidate vaccine in a nursery pig model, using inactivated TX98-129 virus as the backbone. The results demonstrate that pigs immunized with HA-129 developed antibodies against all four parental viruses, as well as additional primary swine H1N1 influenza virus field isolates.

CONCLUSION

This study established a platform for creating novel genes of influenza viruses using a molecular breeding approach, which will have important applications toward future development of broadly protective influenza virus vaccines.

Heterosubtypic antibodies to influenza A virus have limited activity against cell-bound virus but are not impaired by strain-specific serum antibodies

The majority of influenza virus-specific antibodies elicited by vaccination or natural infection are effective only against the eliciting or closely related viruses. Rare stem-specific heterosubtypic monoclonal antibodies (hMAbs) can neutralize multiple strains and subtypes by preventing hemagglutinin (HA)-mediated fusion of the viral membrane with the endosomal membrane. The epitopes recognized by these hMAbs are therefore considered promising targets for the development of pan-influenza virus vaccines. Here, we report the isolation of a novel human HA stem-reactive monoclonal antibody, hMAb 1.12, with exceptionally broad neutralizing activity encompassing viruses from 15 distinct HA subtypes. Using MAb 1.12 and two other monoclonal antibodies, we demonstrate that neutralization by hMAbs is virtually irreversible but becomes severely impaired following virus attachment to cells. In contrast, no interference by human anti-influenza virus serum antibodies was found, indicating that apically binding antibodies do not impair access to the membrane-proximal heterosubtypic epitopes. Our findings therefore encourage development of new vaccine concepts aiming at the induction of stem-specific heterosubtypic antibodies, as we provide support for their effectiveness in individuals previously exposed to influenza virus.

IMPORTANCE

The influenza A virus hemagglutinin (HA) can easily accommodate changes in its antigenic structures to escape preexisting immunity. This variability restricts the breadth and long-term efficacy of influenza vaccines. Only a few heterosubtypic antibodies (hMAbs), i.e., antibodies that can neutralize more than one subtype of influenza A virus, have been identified. The molecular interactions between these heterosubtypic antibodies and hemagglutinin are well characterized, yet little is known about the functional properties of these antibodies. Using a new, extraordinarily broad hMAb, we show that virus neutralization by hMAbs is virtually irreversible and that efficient neutralization is possible only if stem-specific hMAbs bind to HA before the virus attaches to the cell surface. No interference between strain-specific human serum immunoglobulin and hMAbs was found, indicating that preexisting humoral immunity to influenza virus does not limit the efficacy of stem-reactive heterosubtypic antibodies. This knowledge supports the development of a pan-influenza virus vaccine.

Animal models for influenza viruses: implications for universal vaccine development

Influenza virus infections are a significant cause of morbidity and mortality in the human population. Depending on the virulence of the influenza virus strain, as well as the immunological status of the infected individual, the severity of the respiratory disease may range from sub-clinical or mild symptoms to severe pneumonia that can sometimes lead to death. Vaccines remain the primary public health measure in reducing the influenza burden. Though the first influenza vaccine preparation was licensed more than 60 years ago, current research efforts seek to develop novel vaccination strategies with improved immunogenicity, effectiveness, and breadth of protection. Animal models of influenza have been essential in facilitating studies aimed at understanding viral factors that affect pathogenesis and contribute to disease or transmission. Among others, mice, ferrets, pigs, and nonhuman primates have been used to study influenza virus infection in vivo, as well as to do pre-clinical testing of novel vaccine approaches. Here we discuss and compare the unique advantages and limitations of each model.

Barriers and Motivators of Influenza Vaccination Uptake among Primary Healthcare Workers in Singapore

Introduction:

Healthcare workers, especially primary healthcare workers, are at risk of contracting influenza from patients at their workplace. The uptake of influenza immunisation among healthcare workers has been inadequate in spite of this risk and the recommendation to receive annual influenza vaccination. This study aims to assess the barriers as well as the motivators of influenza immunisation among staff from an organisation of primary healthcare polyclinics in Singapore.

Methods:

Focus group interviews were conducted on healthcare workers from different occupation categories within the organisation and results were analysed.

Results:

Factors identified as barriers to influenza immunisation were: misconceptions regarding influenza immunisation, fear of experiencing pain or reaction from the vaccination, influence from other staff, uncertainty over the efficacy of influenza vaccination and perceived immunity against influenza virus. Motivators to immunisation were: the influence of other staff, direction from senior management, incentives for vaccination, accessibility and convenience in receiving the immunisation, reduction in risk of transmitting influenza to others and awareness and knowledge of influenza vaccination.

Conclusion:

Interventions to promote influenza immunisation based on these identified factors may help increase the immunisation uptake among healthcare workers.

Influenza vaccines: unmet needs and recent developments

Influenza is a worldwide public health concern. Since the introduction of trivalent influenza vaccine in 1978, vaccination has been the primary means of prevention and control of influenza. Current influenza vaccines have moderate efficacy, good safety, and acceptable tolerability; however, they have unsatisfactory efficacy in older adults, are dependent on egg supply for production, and are time-consuming to manufacture. This review outlines the unmet medical needs of current influenza vaccines. Recent developments in influenza vaccines are also described.

Influenza vaccine effectiveness during the 2012 influenza season in Victoria, Australia: influences of waning immunity and vaccine match

Vaccine effectiveness may wane with increasing time since vaccination. This analysis used the Victorian sentinel general practitioner (GP) network to estimate vaccine effectiveness for trivalent inactivated vaccines in the 2012 season. A test-negative design was used where patients presenting to GPs with influenza-like illness who tested positive for influenza were cases and noncases were those who tested negative. Vaccination status was recorded by GPs. Vaccine effectiveness was calculated as (1-odds ratio) × 100%. Estimates were compared early versus late in the season and by time since vaccination. Virus isolates were assessed antigenically by hemagglutination inhibition assay in a selection of positive samples and viruses from healthy adults who experienced a vaccine breakthrough were analyzed genetically. The adjusted vaccine effectiveness estimate for any type of influenza was 45% (95% CI: 8,66) and for influenza A(H3) was 35% (95% CI: -11,62). A non-significant effect of waning effectiveness by time since vaccination was observed for A(H3). For those vaccinated <93 days of presentation vaccine effectiveness was 37% (95% CI: -29,69), while for those vaccinated ≥93 days before presentation it was 18% (95% CI: -83,63). Comparison of early versus late in the season estimates was very sensitive to the cut off week chosen for analysis. Antigenic data suggested that low vaccine effectiveness was not associated with poor vaccine match among the A(H3) viruses. However, genetic analysis suggested nucleotide substitutions in antigenic sites. In 2012, the trivalent influenza vaccine provided moderate protection against influenza and showed limited evidence for waning effectiveness. Antigenic and genetic data can provide additional insight into understanding these estimates.

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.

Coverage and parental perceptions of influenza vaccination among parents of children aged 6 to 23 months in Hong Kong

BACKGROUND

The impact of influenza on young children can be severe and even fatal. Influenza vaccination (IV) has been shown to be effective in reducing complications of influenza among children. This study investigated the prevalence and factors of IV among children aged 6-23 months in Hong Kong.

METHODS

A sample of 401 Chinese parents of children aged 6-23 months were interviewed at local Maternal and Child Health Centers. Socio-demographic information, variables related to Health Belief Model, including perceptions about the child's chance of contracting influenza, perceived harm of influenza on children, perceived benefits and side-effects of IV, having received recommendations from health professionals to uptake IV, and IV behaviors of the children were measured. Multivariate analysis was used to examine factors associated with IV behaviors of children.

RESULTS

Only 9% of the children had ever been vaccinated. Among those parents who had heard of IV (92.0%), substantial proportions perceived that IV could reduce the risk of influenza-induced complications (70.5%), hospitalization (70.5%) and death (65.9%). Relatively few of the participants believed that IV had no side effects (17.1%) and even less had been recommended by health care professionals to uptake IV (10.6%). Results from multivariate analysis showed that physician recommendations were associated with a higher likelihood for IV among younger children, whilst parental perceptions of the side effects of IV was associated with a lower likelihood for IV.

CONCLUSION

The prevalence of IV among children aged 6-23 months in Hong Kong was very low. Promotion of IV with the component of physician recommendations and parents' knowledge about IV safety for this group is warranted.

Effectiveness of seasonal influenza vaccine against clinically diagnosed influenza over 2 consecutive seasons in children in Guangzhou, China: a matched case-control study

Influenza vaccine has to be reformulated each year due to the ever-changing antigenicity of the influenza virus. However, few post-licensure studies of influenza vaccine are available in China. We aimed to measure the effectiveness of seasonal influenza vaccine during 2 consecutive seasons. Among children in Guangzhou aged 6 to 59 mo in 2010-2012, we matched each child with clinically diagnosed influenza to 3 healthy children. Cases with clinically diagnosed influenza were identified from surveillance system. Healthy controls were randomly sampled from the Children's Expanded Programmed Immunization Administrative Computerized System. Conditional logistic regression was used to calculate vaccine effectiveness (VE). A total of 275 matched sets of subjects were included. VE levels against clinically diagnosed influenza for both seasons combined was 47.4% [95% confidence interval (CI), 8.5-69.8%] for full vaccination for children aged 6-35 mo, 33.6% (95% CI, 5.4-53.5%) for any vaccination for children aged 6-59 mo, respectively. VE by time since vaccination for any vaccination was 34.6% (95% CI, 4.7-55.2%) in 0-5 mo, and no protection was observed in 6-11 mo. Annual, full and timely vaccination should be encouraged for children.

Cloned defective interfering influenza virus protects ferrets from pandemic 2009 influenza A virus and allows protective immunity to be established

Influenza A viruses are a major cause of morbidity and mortality in the human population, causing epidemics in the winter, and occasional worldwide pandemics. In addition there are periodic outbreaks in domestic poultry, horses, pigs, dogs, and cats. Infections of domestic birds can be fatal for the birds and their human contacts. Control in man operates through vaccines and antivirals, but both have their limitations. In the search for an alternative treatment we have focussed on defective interfering (DI) influenza A virus. Such a DI virus is superficially indistinguishable from a normal virus but has a large deletion in one of the eight RNAs that make up the viral genome. Antiviral activity resides in the deleted RNA. We have cloned one such highly active DI RNA derived from segment 1 (244 DI virus) and shown earlier that intranasal administration protects mice from lethal disease caused by a number of different influenza A viruses. A more cogent model of human influenza is the ferret. Here we found that intranasal treatment with a single dose of 2 or 0.2 µg 244 RNA delivered as A/PR/8/34 virus particles protected ferrets from disease caused by pandemic virus A/California/04/09 (A/Cal; H1N1). Specifically, 244 DI virus significantly reduced fever, weight loss, respiratory symptoms, and infectious load. 244 DI RNA, the active principle, was amplified in nasal washes following infection with A/Cal, consistent with its amelioration of clinical disease. Animals that were treated with 244 DI RNA cleared infectious and DI viruses without delay. Despite the attenuation of infection and disease by DI virus, ferrets formed high levels of A/Cal-specific serum haemagglutination-inhibiting antibodies and were solidly immune to rechallenge with A/Cal. Together with earlier data from mouse studies, we conclude that 244 DI virus is a highly effective antiviral with activity potentially against all influenza A subtypes.

Residual baculovirus in insect cell-derived influenza virus-like particle preparations enhances immunogenicity

Influenza virus-like particles are currently evaluated in clinical trials as vaccine candidates for influenza viruses. Most commonly they are produced in baculovirus- or mammalian- expression systems. Here we used different vaccination schemes in order to systematically compare virus-like particle preparations generated in the two systems. Our work shows significant differences in immunogenicity between the two, and indicates superior and broader immune responses induced by the baculovirus-derived constructs. We demonstrate that these differences critically influence protection and survival in a mouse model of influenza virus infection. Finally, we show that the enhanced immunogenicity of the baculovirus-derived virus-like particles is caused by contamination with residual baculovirus which activates the innate immune response at the site of inoculation.

Comparison of the protection of ferrets against pandemic 2009 influenza A virus (H1N1) by 244 DI influenza virus and oseltamivir

The main antivirals employed to combat seasonal and pandemic influenza are oseltamivir and zanamivir which act by inhibiting the virus-encoded neuraminidase. These have to be deployed close to the time of infection and antiviral resistance to the more widely used oseltamivir has arisen relatively rapidly. Defective interfering (DI) influenza virus is a natural antiviral that works in a different way to oseltamivir and zanamivir, and a cloned version (segment 1 244 DI RNA in a cloned A/PR/8/34 virus; 244/PR8) has proved effective in preclinical studies in mice. The active principle is the DI RNA, and this is thought to interact with all influenza A viruses by inhibiting RNA virus synthesis and packaging of the cognate virion RNA into nascent DI virus particles. We have compared the ability of DI virus and oseltamivir to protect ferrets from intranasal 2009 pandemic influenza virus A/California/04/09 (A/Cal, H1N1). Ferrets were treated with a single 2 μg intranasal dose of 244 DI RNA delivered as 244/PR8 virus, or a total of 25mg/kg body weight of oseltamivir given as 10 oral doses over 5 days. Both DI virus and oseltamivir reduced day 2 infectivity and the influx of cells into nasal fluids, and permitted the development of adaptive immunity. However DI virus, but not oseltamivir, significantly reduced weight loss, facilitated better weight gain, reduced respiratory disease, and reduced infectivity on days 4 and 6. 244 DI RNA was amplified by A/Cal by >25,000-fold, consistent with the amelioration of clinical disease. Treatment with DI virus did not delay clearance or cause persistence of infectious virus or DI RNA. Thus in this system DI virus was overall more effective than oseltamivir in combatting pandemic A/California/04/09.

Predicting vaccination using numerical and affective risk perceptions: the case of A/H1N1 influenza

During the 2009 A/H1N1 flu pandemic, German health authorities recommended vaccination; however, the efficacy of such programs largely depends on individuals' risk perception. Risk perceptions are commonly determined through numerical-cognitive estimates such as the perceived likelihood and severity of the hazard. Instead, we argue that risk perceptions, which include more affect-related aspects such as worry and threat, are more powerful predictors of protective behaviors. Moreover, vaccines are often perceived as double-edged since they offer protection but also involve adverse side-effects. As such, in the context of the A/H1N1 vaccine uptake, risk perception is not only disease-related (A/H1N1 infection) but also vaccine-related (A/H1N1 vaccine). The present longitudinal study was conducted during the run-up to the German A/H1N1 vaccination campaign and measured cognitive and affective risk perceptions associated with both the A/H1N1 infection and its vaccine (T1, October 2009, N=397) in order to assess their impact on (self-reported) A/H1N1 vaccination eight weeks later (T2, December 2009; N=285). As assumed, greater perceived likelihood and severity of infection were associated with greater affective risk perception at T1. The more threatened and worried people felt, the more they intended to get vaccinated; however, the greater the perceived likelihood and severity of vaccine adverse side-effects, the greater the amount of vaccine related affective risk perception, impeding vaccination intention. Finally, vaccination intention predicted vaccination eight weeks later at T2 (OR=2.2). The results suggest that numerical-cognitive risk perceptions, which are typically the target of public vaccination campaigns, do not impact preventive intention directly; instead, they facilitate affect-related risk perceptions, which motivate protective action.

[Vaccination against seasonal influenza in France in 2010 and 2011: decrease of coverage rates and associated factors]

AIM

To measure the seasonal influenza vaccination coverage rate (VCR) in France in 2010, one year after the A(H1N1) influenza pandemic, and 2011 by age and target disease and to identify risk factors associated with a lack of vaccination in 2010 for those previously vaccinated in 2009.

METHODS

At the beginning of each vaccination campaign, the National Health Insurance, covering 86% of the French population, sends free influenza vaccination vouchers to at-risk beneficiaries aged under 65 suffering from diverse target diseases and to all individuals aged 65 and over (around 11.5 million).

RESULTS

The global VCR (50.4%), except people with asthma identified by drug refunds, decreased in 2010 compared with the previous three years when it was close to 60% (51.0% in 2011). For people under 65 years old, it fell from 40.3% in 2009 to 31.6% in 2010 (33.1% in 2011) and those aged 65 years and over from 63.3% to 53.8% (54.0% in 2011). The VCR of each target disease also decreased, especially for asthma, but not for HIV infection with campaign modification in 2010. It decreased among those aged 65 years and over with target disease (72.3% in 2009, 60.4% in 2010, 60.7% in 2011). Vaccination lack in 2010 was found to be associated with younger age, low number of drug deliveries and consultations with a general practitioner or a specialist, hospitalisation and the residence in a region of South of France or in overseas regions.

CONCLUSION

An important decline of the VCR was observed in France since 2010 while the recommended VCR is 75%. Efforts must be led to improve the confidence of the insurant, especially towards the most fragile groups.

Knowledge, attitudes and perceptions of health professionals in relation to A/H1N1 influenza and its vaccine

OBJECTIVE

To determine the intention of health professionals, doctors and nurses, concerning whether or not to be vaccinated against A/H1N1 influenza virus, and their perception of the severity of this pandemic compared with seasonal flu.

MATERIAL AND METHODS

A cross-sectional study was carried out based on an questionnaire e-mailed to health professionals in public healthcare centres in Vitoria between 6 and 16 November 2009; the percentage of respondents who wanted to be vaccinated and who perceived the pandemic flu to carry a high risk of death were calculated.

RESULTS

A total of 115 people completed the questionnaire of whom 61.7% (n=71) were doctors and 38.3% (n=44) were nurses. Of these, 33.3% (n=23) of doctors and 13.6% (n=6) of nurses intended to be vaccinated (p=0.019). Even among those who considered themselves to be at a high risk, 70.6% (n=48) of doctors and 31.7% (n=13) of nurses participating in the study (p=0.001) planned to have the vaccination.

CONCLUSIONS

Most health professionals, and in particular nurses, had no intention to be vaccinated against A/H1N1 influenza virus at the beginning of the vaccination campaign.

The cost-effectiveness and value of information of three influenza vaccination dosing strategies for individuals with human immunodeficiency virus

Background

Influenza vaccine immunogenicity is diminished in patients living with HIV/AIDS. We evaluated the cost-effectiveness and expected value of perfect information (EVPI) of three alternative influenza vaccine dosing strategies intended to increase immunogenicity in those patients.

Methods

A randomized, multi-centered, controlled, vaccine trial was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine were used in HIV infected adults: two standard doses over 28 days (Strategy A), two double doses over 28 days (Strategy B) and a single standard dose of influenza vaccine (Strategy C), administered prior to the 2008 influenza season. The comparator in our analysis was practice in the previous year, in which 82.8% of HIV/AIDS received standard-dose vaccination (Strategy D). A Markov cohort model was developed to estimate the monthly probability of Influenza-like Illness (ILI) over one influenza season. Costs and quality-adjusted life years, extrapolated to the lifetime of the hypothetical study cohorts, were estimated in calculating incremental cost-effectiveness ratios (ICER) and EVPI in conducting further research.

Results

298 patients with median CD4 of 470 cells/µl and 76% with viral load suppression were randomized. Strategy C was the most cost-effective strategy for the overall trial population and for suppressed and unsuppressed individuals. Mean ICERs for Strategy A for unsuppressed patients could also be considered cost-effective. The level of uncertainty regarding the decision to implement strategy A versus C for unsuppressed individuals was high. The maximum acceptable cost of reducing decision uncertainty in implementing strategy A for individuals with unsuppressed pVL was $418,000 - below the cost of conducting a larger-scale trial.

Conclusion

Our results do not support a policy to implement increased antigen dose or booster dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine for individuals with HIV in Canada.

Trial Registration

ClinicalTrials.gov NCT00764998.