Influenza immunization policies in Europe and the United States

Seasonal Influenza Vaccination at a German University Hospital: Distinguishing Barriers Between Occupational Groups

The annual influenza vaccination has been officially recommended for medical staff in Germany since 1988. Nevertheless, the vaccination rate among medical staff is still low. The present study deals with the influenza vaccination rate of staff at a German University hospital over time as well as with the reasons that led to a positive vaccination decision and the barriers to acceptance of vaccination. For this purpose, the staff members received questionnaires in which they were asked about influenza vaccination and the reasons for or against vaccination. In addition, the questionnaire contains information on gender, age group, occupational group and presence of a chronic co-morbidity. Logistic regression analysis was used to investigate which of these predictors most strongly influenced the vaccination decision. It was shown that the reasons for or against vaccination differ significantly between the occupational groups and that the occupational group affiliation has the greatest influence on the vaccination decision in the comparison of the investigated predictors. In order to achieve a positive influence on vaccination acceptance, future measures should focus on increasing confidence in vaccination and on increasing the perception of risk from influenza illness. The findings may contribute to future targeted strategies to increase vaccination rates and suggest occupational group-specific interventions.

Influenza virus surveillance among young children in São Paulo, Brazil: the impact of vaccination

This study assessed the presence of influenza virus among young children and the coverage of vaccination from 2010 to 2012 in São Paulo, Brazil. Our results demonstrated a lower rate of influenza detection and a predominance of influenza B. A decrease of coverage vaccination through the surveillance periods was observed.

Understanding Australian healthcare workers' uptake of influenza vaccination: examination of public hospital policies and procedures

BACKGROUND

In Australia, whether to provide free influenza vaccine to health care workers (HCWs) is a policy decision for each hospital or jurisdiction, and is therefore not uniform across the country. This study explored hospital policies and practices regarding occupational influenza vaccination of HCWs in Australia.

METHODS

A study using qualitative methodology, which included semi-structured interviews, was undertaken with hospital staff involved with the delivery of occupational influenza vaccination from three states in Australia.

RESULTS

The 29 participants were responsible for vaccinating staff in 82 hospitals. Major themes in the responses were the lack of resources and the difficulties participants faced in procuring any additional support or funding from their institutions. All study sites provided vaccine free of charge to employees via on-site clinics or mobile carts, and used multiple strategies to inform and educate their staff. In some instances, declination forms had been adopted, however their use was associated with resourcing issues, animosity, and other problems. Participants who were responsible for multiple sites were more likely to recount lower vaccination coverage figures at their hospitals.

CONCLUSIONS

From these interviews, it is clear that hospitals are implementing multiple strategies to educate, promote, and deliver the vaccine to staff. However, resources and support are not always available to assist with the vaccination campaign. The reality for many hospitals is that there is limited capacity to implement the vaccination campaigns at the levels high enough to raise compliance rates. Further research needs to be conducted to quantify the factors contributing to higher uptake in the Australian hospital setting.

Does vaccinating ED health care workers against influenza reduce sickness absenteeism?

This study aims to investigate the association between influenza vaccination of health care workers (HCWs) and sickness absenteeism. A retrospective cohort study was conducted in an emergency department (ED) of an acute care hospital. All full-time HCWs except physicians (73 nurses and health care attendants) were included. Influenza vaccine was administered to HCWs on a voluntary basis commencing November 2004. Absenteeism due to influenza-like illness during the period from January to October 2005 was noted. The mean number of cumulative sick leave days per person was smaller (1.0 days against 1.75 days) in vaccine recipients than in vaccine nonrecipients although the difference was not statistically significant. A significantly larger proportion of subjects took sick leave because of influenza-like illness in the vaccine nonrecipient group (55% against 30.3%, P = .034).

CONCLUSION

Influenza vaccination of HCWs in the ED setting is significantly associated with a fewer number of HCWs requiring sick leave.

In a prospective observational study, influenza vaccination prevented hospitalization among older home care patients

OBJECTIVE

The aim of the study is (1) to describe the prevalence of vaccination against influenza in older home care patients and (2) to investigate the protective effect of influenza vaccination for hospitalization events.

STUDY DESIGN AND SETTING

This is an observational study conducted in four large cohorts of elderly patients in home care during the 1998-1999, 1999-2000, 2000-2001, and 2001-2002 influenza seasons. We analyzed data from the Italian Silver Network Home Care project. A total of 2,201 patients were enrolled in the present study. The main outcome measures were prevalence of vaccination against influenza and the rate of hospitalization according to vaccination status and influenza season.

RESULTS

The rate of influenza vaccination was around 48% of the studied sample. During the follow-up including the peak of influenza and the total influenza season, 412 subjects (40%) were hospitalized among vaccinated compared to 610 subjects (59%) among not vaccinated (P<0.001). After adjusting for age, gender, location of home care program, and all the variables significantly different between vaccinated and not-vaccinated subjects, vaccinated subjects were less likely to be hospitalized compared to not-vaccinated subjects (OR, 0.73; 95% CI 0.60-0.90).

CONCLUSIONS

Vaccination against influenza has an important prognostic implication for frail geriatric patients living in the community.

Factors that affect influenza vaccine uptake among staff of long-term care facilities

A survey of directors and employees of 36 long-term care facilities in Hesse, Germany, revealed that influenza vaccine uptake among staff was less than 30% in 30 and greater than 50% in 6. The study identified policies and practices associated with vaccination uptake at long-term care facilities and factors associated with the decision of staff to get vaccinated.

Is influenza vaccination in asthmatic children helpful?

The rationale for influenza vaccination in asthmatic children theoretically lies in prevention of exacerbations and serious complications like pneumonia. Solid evidence from randomized clinical trials of its preventive effects on these clinical endpoints is, however, lacking. Nevertheless, most Western guidelines advise to vaccinate these children. In the real life situation this advice isn't very well followed: vaccine coverage for this indication is low. To assess the usefulness of influenza vaccination in children with asthma a set of fundamental questions regarding this activity is presented and answered. This leads to the conclusion that, given the evidence, influenza vaccination in children with mild to moderate disease should be reconsidered.

Cell-mediated immune responses to influenza vaccination in healthy volunteers and allogeneic stem cell transplant recipients

Influenza is one of the most common respiratory diseases in humans. The response to vaccination is frequently poor in immunosuppressed individuals. The aim of the present study was to develop an enzyme-linked immunospot (ELISPOT) assay for measuring of the specific T-cell response to influenza vaccination. In all, 18 healthy subjects and six stem cell transplantation (SCT) patients tested before and 4 weeks after influenza vaccination were included in the present study. Peripheral blood lymphocytes were stimulated with four influenza peptides; three based on sequences from the hemagglutinin and one from the M1 protein. The ELISPOT assay and the measurement of intracellular IFN-gamma production were used to determine the cell-mediated responses after stimulation with the peptides. Influenza vaccination elicited strong cell-mediated immune responses in the healthy controls to all four peptides with 3.2-6.9-fold increases in the number of IFN-gamma producing spots/10(6) cells. By intracellular staining, it was suggested that CD4+ cells mediated the responses to the hemagglutinin peptides. In contrast, there was no increase in the number of IFN-gamma producing cells response after vaccination in the six SCT patients. In conclusion, our results suggest that the ELISPOT assay might be used as a complement to serology for monitoring of future influenza vaccine studies in SCT patients.

Is influenza vaccination in asthma helpful?

PURPOSE OF REVIEW

Influenza infections are frequently involved in asthma exacerbations. During influenza epidemics substantial excess morbidity due to respiratory tract complications is reported in all age categories as well as excess mortality among the elderly. Vaccines are available for protection against influenza. Worldwide, vaccination is advised and considered a quality point for asthma care. However, the protective effect of influenza vaccination in patients with asthma is still disputed. In order to establish the current state of affairs we reviewed the recent literature on the protective effect of influenza vaccination and its usefulness in patients with asthma.

RECENT FINDINGS

Several studies were found addressing influenza and the protective aspects of vaccination. They discussed the incidence, the adverse effects of vaccination, the coverage of influenza vaccination among patients with asthma and the effectiveness of the vaccine.

SUMMARY

Influenza vaccination can safely be used in patients with asthma. Allegations that vaccination could provoke asthma exacerbations are convincingly invalidated by previous and recent research. Although patients with asthma are one of the major target groups for immunization, vaccine coverage in all age categories remains low. So far, no unequivocal beneficial effect of influenza vaccination in patients with asthma was found in observational and experimental studies in the sense of reduction of asthma exacerbations and other complications. Recent studies confirm these negative findings. More long-term randomized, placebo-controlled studies, focusing on influenza- proven illness in patients with asthma, are needed to address the question of how helpful influenza vaccination is in these patients.

Protection of inactivated influenza virus vaccine against lethal influenza virus infection in diabetic mice

Influenza virus infection frequently causes complications and some excess mortality in the patients with diabetes. Vaccination is an effective measure to prevent influenza virus infection. In this paper, antibody response and protection against influenza virus infection induced by vaccination were studied in mouse model of diabetes. Healthy and diabetic BALB/c mice were immunized once or twice with inactivated influenza virus vaccine at various dosages. Four weeks after the first immunization or 1 week after the second immunization, the mice were challenged with influenza virus at a lethal dose. The result showed that the antibody responses in diabetic mice were inhibited. Immunization once with high dose or twice with low dose of vaccine provided full protection against lethal influenza virus challenge in diabetic mice, however, in healthy mice, immunization only once with low dose provided a full protection.

Prevalence and predictors of influenza vaccination among frail, community-living elderly patients: an international observational study

The annual winter outbreak of influenza is one of the major cause of morbidity and mortality among frail elderly people. The aim of the present study was to identify prevalence and predictors of influenza vaccination in a large European population of frail and old people living in community. This was an observational study conducted in 11 European countries. We enrolled 3878 people 65 years and older already receiving home care services within the urban areas. All participants were assessed with the Minimum Data Set-Home Care (MDS-HC) instrument containing over 300 items, including socio-demographic, physical and cognitive characteristics of patients as well as medical diagnoses and medications received. A single question about the influenza vaccination status was used. The rate of influenza vaccination was around 59% of the studied sample. Significant geographical variations were evident in the prevalence of vaccination ranging from 31% of Prague (Czech Republic) to 88% of Rotterdam (The Netherlands). Overall, persons living alone were less likely to receive influenza vaccine as compared with those living with an informal caregiver (OR, 0.78; 95% CI 0.67-0.90). Similarly, cognitive impairment and presence of economic problems were associated with a lower likelihood of being vaccinated (OR: 0.69, 95% CI 0.59-0.80 and OR, 0.58; 95% CI 0.45-0.74, respectively). On the other hand, old age and comorbidity were associated with an higher probability of being vaccinated. In conclusion, more than 40% of subjects in this sample of home care patients in Europe did not receive influenza vaccination. Recommendations for influenza vaccination have not been adequately implemented.

Incidence of influenza and associated illness in children aged 0-19 years: a systematic review

A systematic review was conducted to estimate the incidence of influenza and concomitant morbidity and mortality in children from 0 to 19 years (0-19 years). Medline was searched for observational studies and placebo or non-treated arms of experimental studies providing occurrence rates of laboratory-proven influenza illness. From the 2758 titles identified, 356 full papers were reviewed based on the abstract or title; after searching their reference lists an additional 16 papers were found. Finally 28 studies met our inclusion criteria, reporting a varying seasonal incidence of influenza of up to 46%. However, when analysing two long-term observational studies and averaging seasonal fluctuations, the overall incidence of influenza was found to range from 5% to 9.5% per year. Serious morbidity was seldom reported and no cases of mortality were found. Our review shows influenza as an infection with a moderate average incidence and a self-limiting character that is associated with mild morbidity and rare cases of mortality in children. This systematic review may be subject to two contrasting biases. First, the limited number of children reported in the literature with proven influenza infections would tend to under-represent the incidence of uncommon but serious complications such as death. Second, the preferential reporting of influenza outbreak seasons may over-estimate the importance of influenza. Future population based studies should focus on consecutive influenza seasons and capture indirect benefits of vaccinations such as interruption of transmission in the community so that preventive strategies for children can be reconsidered with special attention to their cost effectiveness.

Influenza vaccination in children with asthma: randomized double-blind placebo-controlled trial

There is little evidence that influenza vaccination reduces asthma exacerbations. We determined whether influenza vaccination is more effective than placebo in 6-18-year-old children with asthma. We performed a randomized, double-blind, placebo-controlled trial. Parenteral vaccination with inactivated influenza vaccine or placebo took place approximately November 1, and children were followed until April 1 of the next year. Airway symptoms were reported in a diary. When symptom scores reached a predefined level, a pharyngeal swab was taken. Primary outcome was the number of asthma exacerbations associated with virologically proven influenza infection. Three hundred forty-nine children were assigned placebo, and 347 were assigned vaccine. Pharyngeal swabs positive for influenza were related to 42 asthma exacerbations, 24 in the vaccine group and 18 in the placebo group, a difference of 33% favoring placebo (31% after adjustment for confounders; 95% confidence interval, -34% to 161%). Influenza-related asthma exacerbations were of similar severity in both groups; they lasted 3.1 days shorter in the vaccine group (95% confidence interval, -6.2 to 0.002 days, p = 0.06). We conclude that influenza vaccination did not result in a significant reduction of the number, severity, or duration of asthma exacerbations caused by influenza. Additional studies are warranted to justify routine influenza vaccination of children with asthma.

The comparison of antibody response to influenza vaccination in continuous ambulatory peritoneal dialysis, hemodialysis and renal transplantation patients

BACKGROUND

The immune system in renal transplant (Tx), Continuous Ambulatory Peritoneal Dialysis (CAPD) and hemodialysis (HD) patients have been suppressed and antibody response to vaccination is weaker than that of the normal population. Additionally immune response to vaccination also differs from each other in aforementioned three groups resulting from different levels immunosuppression. In the present study, detection of antibody response to influenza vaccine as an indicator of the level of immunity in Tx, CAPD and HD patients was aimed

PATIENTS AND METHODS

Forty-eight patients (17 Tx, 16 CAPD and 15 HD) and 10 healthy adults, as a control group were enrolled into the study. Purified, split-virus, commercial trivalent influenza vaccine (VAXIGRIP--Pasteur Merieux Connaught, single dose of 0.5 ml into the deltoid muscle) containing 15 microg of each hemagglutinin of A/Johannesburg/82/96 (H1N1), A/Nachang/933/95 (H3N2) and B/Harbin/07/94 (B) strains were administered to all subjects. Serum samples were collected before and 1 month after vaccination to determine antibody titers. Hemagglutination-inhibition test (HI) was applied for determination of antibody response. The antibody response against each strain was measured separately. In addition to measurement of antibody response, increments in antibody titer (n-fold increase in titer), proportion of patients with protective antibody levels and seroconversion levels were taken into account. Wilcoxon paired 2 test and Mann-Whitney U test were applied for statistical analysis. p < 0.05 was accepted as significance level.

RESULTS

Significant increases in antibody titers for all three antigens were observed in the study groups after vaccination (p = 0.001). However, the increase in titer of H3N2 was lower in Tx, CAPD and HD patients than that of the control group (1.0-2.0 vs 5.00) (p = 0.01). The proportion of protective antibody titers and seroconvertions were increased after vaccination in all subjects. Proportions of patients with protective antibody titers after vaccination were lower in Tx, CAPD and HD groups in comparison to control group.

CONCLUSION

Although antibody titers in Tx, CAPD and HD patients presented significant increases after vaccination, the proportions of patients with protective antibody titers were lower in comparison to control group. Tx, CAPD and HD patients should be vaccinated every year to be able avoid potential morbidity and mortality of the influenza infection. Trial of high dose vaccination protocols may be useful to increase the proportion of patients with protective antibody levels.

Effects of influenza vaccination on mortality among frail, community-living elderly patients: an observational study

BACKGROUND AND AIMS

The annual winter outbreak of influenza is one of the major causes of morbidity and mortality among frail elderly people. The aims of the present study were to describe the prevalence of vaccination against influenza in a population of older people living in the community, and to examine the relationship between influenza vaccination and mortality.

METHODS

This was an observational cohort study. We analyzed data from the Italian Silver Network Home Care project, which collected data on patients admitted to home care programs. A total of twelve Home Health Agencies participated in this project, evaluating the implementation of the Minimum Data Set for Home Care (MDS-HC) instrument. A total of 2082 patients were enrolled in the present study. The main outcome measures were prevalence of vaccination against influenza and 1-year survival according to vaccination status.

RESULTS

Nearly half the subjects in our Italian sample did not receive influenza vaccination. During a mean follow-up period of 10 months from initial MDS-HC assessment, 167 vaccinated subjects (15%) died compared with 192 non-vaccinated subjects (19%) (p = 0.01). After adjusting for age, gender, and all variables significantly different between vaccinated and non-vaccinated subjects at baseline (functional and cognitive impairment, number of diseases, number of medications, depression, pressure ulcers), vaccinated subjects were less likely to die than non-vaccinated ones (RR 0.73; 95% CI 0.56-0.94).

CONCLUSIONS

Vaccination against influenza has important prognostic implications for frail geriatric patients living in the community, independent of age, gender, and other clinical and functional variables. Despite extensive scientific evidence, recommendations for annual vaccination against influenza among subjects at higher risk have never been adequately implemented.

Influence of high-risk medical conditions on the effectiveness of influenza vaccination among elderly members of 3 large managed-care organizations

This serial cohort study assessed the risk of hospitalization or death associated with influenza and the effectiveness of influenza vaccination among subgroups of elderly members of 3 managed-care organizations in the United States. Data on baseline characteristics and outcomes were obtained from computerized databases. A total of 122,974 (1996-1997 season) and 158,454 (1997-1998 season) persons were included in the cohorts. Among unvaccinated persons, hospitalizations for pneumonia/influenza or death occurred in 8.2 of 1000 healthy and 38.4 of 1000 high-risk persons in year 1, and in 8.2 of 1000 healthy and 29.3 of 1000 high-risk persons in year 2. After adjustments, vaccination was associated with a 48% reduction in the incidence of hospitalization or death (95% confidence interval [CI], 42-52) in year 1 and 31% (95% CI, 26-37) in year 2. Effectiveness estimates were statistically significant and generally consistent across the healthy and high-risk subgroups. The absolute risk reduction, however, was 2.4- to 4.7-fold higher among high-risk than among healthy elderly persons. All elderly individuals may substantially benefit from vaccination. However, the impact of influenza is greater in persons with high-risk medical conditions.

Policies, principles and pragmatism: old age psychiatrists' attitudes and practice regarding influenza immunisation for long stay patients

This study aimed to examine the attitudes and practice of old age psychiatrists with respect to influenza immunisation for their patients in long stay care. A questionnaire was mailed out with a copy of the government immunisation policy. There was considerable disagreement among responders regarding the government policy, quality of life issues and the appropriateness of immunisation. There was a consensus in favour of immunising those who could not consent and for seeking relatives' views in this scenario. Staff immunisation status and patients' prior wishes were highlighted, amongst other factors, as affecting immunisation decisions. The government policy might be more acceptable to psychiatrists if there was more emphasis on the individual nature of clinical decisions and the policy will have to change in the light of new legislation.

Cost effectiveness of influenza vaccination for healthy persons between ages 65 and 74 years

Healthy persons between 65 and 74 years of age represent a large proportion of the population in this age group. Internationally, there is a substantial variation in whether these people are included among the recommendations for routine influenza vaccination. We therefore conducted this study, updating an earlier analysis, to assess the health and economic benefits of routine influenza vaccination of healthy persons between 65 and 74 years of age. The health benefits associated with vaccination were estimated using the administrative data bases of a large HMO in the Minneapolis, St. Paul, Minnesota area. Multivariate models were used to estimate reductions in hospitalization and death associated with vaccination. The economic analysis took the societal perspective and presented the results as net cost or saving per 10,000 persons vaccinated and per death prevented. Direct and indirect monetary costs were included in the models and were estimated from the published literature. Monte Carlo simulation was used to conduct probabilistic sensitivity analysis in order to derive probability intervals for each estimate of net costs or savings. Over the six consecutive study seasons, 1990-1991 to 1995-1996, vaccination of healthy elderly person was associated with a 36% reduction in hospitalization for pneumonia or influenza (95% CI, 2-39%), an 18% reduction in hospitalization for all respiratory conditions (95% CI, -6 to 37%) and a 40% reduction in death (95% CI, 14-38%). Vaccination was also associated with cost savings in all scenarios evaluated. The findings of this study again affirm the value of an age-based strategy for routine influenza vaccination of all elderly persons including healthy elderly persons between 65 and 74 years.

Cost-effectiveness of influenza vaccination in high-risk children in Argentina

OBJECTIVES

our study aimed to evaluate the cost-effectiveness of influenza vaccination in high-risk children in Argentina.

METHODS

a decision analysis model was performed, using data from published and unpublished sources, to compare two strategies--to vaccinate or not to vaccinate. We simulated the expected consequences of vaccination on direct medical costs, related to disease management and indirect costs, related to lost parental working days (absenteeism).

RESULTS

Using base-case assumptions vaccination of high-risk children aged 6 months to 15 years old, in Argentina (estimated cohort of 1184748) would prevent 207331 cases of influenza, resulting in a reduction of 58052 days of hospitalization and 207331 outpatient visits. Vaccination would lead to net savings of US$ 11894870 per vaccinated cohort (US$ 10.04 per vaccinated child).

CONCLUSION

our economic analysis shows that in Argentina, routine vaccination of high-risk children against influenza would be cost saving for society.

Influenza: vaccination and treatment

Few conditions exert such an enormous toll of absenteeism, suffering, medical consultations, hospitalization, death and economic loss as influenza. Patients at high risk of complications and mortality include the elderly and those with pre-existing cardiopulmonary disease. The outbreak in 1997 in Hong Kong, of avian H5N1 influenza in man, which resulted in six deaths among 18 hospitalized cases, and the recent isolation of H9N2 viruses from two children in Hong Kong, are reminders that preparation must be made for the next pandemic. Since the 1970s, efforts to control influenza have mostly focussed on the split product and surface antigen vaccines. These vaccines are of proven efficacy in healthy adults and are effective in elderly people with and without medical conditions putting them at high risk of complications and death following influenza infection. However, vaccine coverage is patchy and often low, and outbreaks of influenza are not uncommon in well-immunized residents of nursing homes. New vaccines and methods of vaccine delivery are being developed in attempts to overcome the limitations of existing vaccines. The antiviral drugs amantadine and rimantadine were developed in the 1960s, but have not been used widely due to their spectrum of activity, rapid emergence of resistance, and adverse effects associated with amantadine. The site of enzyme activity of the influenza neuraminidase is highly conserved between types, subtypes and strains of influenza and has emerged as the target of an exciting new class of antiviral agents that are effective both prophylactically and as therapy.

Influenza vaccination coverage in old people's home in Carmarthenshire, UK, during the winter of 1998/99

A mailed questionnaire survey was undertaken in old people's (nursing and residential) homes in Carmarthenshire, UK to determine the influenza vaccine uptake during the 1998/99 season. Out of the total 60 questionnaires circulated, response was received from 47 homes giving an overall response rate of 78%. Amongst the 1399 residents, 1132 (81%) received influenza vaccine in the winter of 1998/99. Uptake was higher in nursing homes (89%) than in residential homes (79%) or dual registered homes (81%). The most common reason for not receiving influenza vaccination was refusal by the residents themselves, although the vaccine was offered to 99% of residents. This study suggests that strategies to improve communication and provision of educational materials outlining the benefits of influenza vaccine to elderly residents and health professionals may help increase the likelihood of vaccine uptake.

Comparison of immunogenicity and safety of a virosome influenza vaccine with those of a subunit influenza vaccine in pediatric patients with cystic fibrosis

The objective of this study was to compare the immunogenicity and safety of a single-dose regimen and a two-dose regimen of a trivalent virosome influenza vaccine (Inflexal Berna V) with those of a trivalent subunit influenza vaccine (Influvac) in children and adolescents with cystic fibrosis (CF). In an open, randomized, multicenter study with parallel groups, 11 young children with CF (1 to 6 years old) and 53 older children and adolescents with CF (>6 years old) were randomly assigned to one of the following immunization regimens: virosome vaccine at 0.5 ml on study day 0 or 0.25 ml on days 0 and 28 or a standard regimen of subunit vaccine, i. e., 0.5 ml on day 0 for older children and 0.25 ml on days 0 and 28 for younger children. Safety assessments, i.e., recording of systemic and local adverse events (AEs) and vital signs, were made for a 5-day observation period after each immunization. Hemagglutination inhibition (HI) titers were determined at baseline and 4 weeks after the single-dose and the two-dose immunizations, respectively. Immunogenicity was assessed according to the criteria of the European Agency for the Evaluation of Medicinal Products (EMEA). Both vaccines induced comparable HI antibody titers. Seroconversion (> or =4-fold rise in HI antibody titers, reaching a titer of > or =1:40) was achieved in 41 to 100% of the participants. Seroprotection (HI titer, > or =1:40) and a >2.5-fold increase in geometric mean titers were achieved in 100% of the participants. Thus, all three EMEA requirements for influenza vaccine efficacy were met by all treatment groups and for both vaccines. The virosome vaccine, when administered as a single dose, seemed to induce superior immunogenicity compared with the standard pediatric two-dose regimen. Totals of 42 and 57% of vaccinees receiving virosome and subunit vaccines, respectively, reported at least one local AE (predominantly pain). Totals of 84 and 71% of subjects receiving virosome and subunit vaccines, respectively, complained in response to questions of at least one systemic AE (mainly cough, fatigue, coryza, or headache). The majority of events were mild or moderate and lasted 1 or 2 days only. No obvious relationship was found between AE reporting rate and vaccine formulation, age group, or dose regimen. The relatively high AE reporting rate seemed to be partly related to the symptomatology of the underlying CF disease. In summary, the virosome and subunit vaccines induced in both age groups and against all three influenza strains an efficient immune response and were well tolerated by the children and adolescents with CF.

Rapid antibody response to influenza vaccination in "at risk" groups

Persons attending for routine influenza vaccination in an urban practice each provided three specimens of blood for evaluating their immunological response. 138 (67%) of the 206 persons were defined as "at risk" by reason of morbidity as given in the guidelines published by the Chief Medical Officer. The mean age was 67 yr and 65% were aged 65 yr or more. By day 7, 71% of 31 persons had protective H(1)N(1) titres, 61% H(3)N(2) and 42% B. These proportions were similar to those found at day 14 and at day 21 based on 159 persons. These findings suggest that an effective immune response is mounted within seven days of vaccination indicating that the vaccination of persons "at risk" is worthwhile even after an epidemic has established itself. This is not a reason to modify present policy of routine vaccination in early winter well before epidemics are likely to occur.

Control of influenza. Public health policies

The control and management of influenza are currently based on the surveillance, prevention and treatment of the disease. Almost all European countries have influenza immunization policies for populations considered as being at-risk, but there are large disagreements about the meaning of "risk", and the levels of vaccine use vary greatly country by country. In the near future, new vaccines and specific anti-viral drugs will need to adapt and to extend current recommendations, but meanwhile increasing vaccination coverage, improving and up-dating national policies and their achievement are the only ways to reduce the recurrent burden of influenza epidemics for both individuals and society.

Randomized, placebo-controlled double blind study on the efficacy of influenza immunization on absenteeism of health care workers

BACKGROUND

In healthy adults influenza immunization reduces absenteeism caused by respiratory infections, but data on its efficacy among health care workers are scarce.

OBJECTIVE

To determine the effect of the conventional inactivated influenza A vaccine on reducing absenteeism related to respiratory infections among pediatric health care providers.

STUDY DESIGN

A randomized, placebo-controlled, double blind study on vaccine efficacy was conducted in two pediatric hospitals during the winter season 1996 to 1997. The primary endpoint was days of work lost from the hospital because of respiratory infections. The documentation of absenteeism was based on personal sickness logs.

RESULTS

Of the 547 randomized vaccinees 427 (78%) persons completed the 4-month follow-up and returned the sickness logs. Immunization failed to reduce episodes of respiratory infections (1.8 episodes/study period among vaccinees vs. 2.0 among controls). Similarly the vaccine failed to affect the total number of days the vaccinees suffered from respiratory infections (13.5 days vs. 14.6 days, respectively). However, days of work lost because of respiratory infections (1.0 days vs. 1.4 days, respectively, P = 0.02) and especially total numbers of days the study persons felt themselves unable to work when either on or off duty (2.5 days vs. 3.5 days, P 0.02) were significantly decreased.

CONCLUSION

Influenza vaccination reduced absenteeism related to respiratory infections by 28%. We therefore believe that routine annual influenza immunizations should be recommended to health care providers working in pediatric settings.

Complications of influenza and benefits of vaccination

Uncertainty regarding the benefits of influenza vaccination may contribute to the underutilization of this vaccine. We have conducted serial cohort studies using the administrative data bases of a Twin Cities based managed care organization to assess the impact of disease and benefits of vaccination among the elderly. For the 6 seasons 1990-1991 through 1995-1996, there were more than 20,000 elderly members of the health plan included in each cohort. Data collected included information on baseline demographic and health characteristics, vaccination status and outcomes (hospitalizations and death). Multivariate regression techniques were used to compare the risks of outcomes between vaccinated and unvaccinated persons while controlling for covariates and confounders. Results for data pooled over the 6 seasons demonstrated that influenza vaccination was associated with significant reductions in hospitalizations, outpatient visits, and death among the elderly. Similar findings were observed for low, intermediate, and high risk subgroups. Vaccination was also associated with cost savings. These findings are consistent with results from studies conducted in other countries and over other seasons and strongly support age-based recommendations for annual influenza vaccination for all persons ages 65 and over.

Effects of inactivated influenza virus vaccination on bronchial reactivity symptom scores and peak expiratory flow variability in patients with asthma

Even though annual influenza vaccinations are recommended by many authorities, some doctors may be reluctant to vaccinate asthmatic patients because of the risk of inducing bronchial reactivity and exacerbating the asthma. In this study we investigated the effect of inactivated trivalent influenza vaccine on airway reactivity symptom scores and peak expiratory flow (PEF) variability in 24 patients with mild stable asthma. Baseline spirometry and methacholine challenge tests were performed on all patients. Patients were then asked to record their peak expiratory flow every morning and evening, complete daily symptom score charts (morning tightness, daytime asthma, cough, and night asthma), and note bronchodilator usage for 1 week. After baseline measurements, the patients were allocated to inactivated vaccine and placebo in a random and single-blind manner. The lung function measurements and methacholine challenge tests were repeated 1 week after vaccination and placebo administration at the same time of day. PD20 (mg/mL) methacholine doses were 3.06+/-3.0 mg/mL before vaccination, 2.96+/-3.2 mg/mL after vaccination, and 2.76+/-2.91 mg/mL after placebo administration. There were no significant changes in PD20 methacholine after influenza vaccination (p>0.05). There were also no significant changes in symptom scores, bronchodilator usage, and PEFR after vaccination (p>0.05). None of the patients experienced significant local or systemic side effects after vaccination. Immunization with inactivated influenza vaccine does not induce clinical exacerbations of asthma or airway hyperreactivity in patients with mild asthma.

Effects of influenza vaccination and influenza illness on exacerbations in multiple sclerosis

Despite reports that influenza vaccination appears to be safe in multiple sclerosis there is uncertainty which patients may benefit from it. By using a questionnaire we compared the effects of influenza illness (1995-1996 season) and influenza vaccination (autumn of 1996) on neurologic symptoms in patients with multiple sclerosis registered in the Groningen Multiple Sclerosis Data Bank. No clinically relevant effects were reported in 53 patients with primary progressive multiple sclerosis, either following vaccination or the illness. In a group of 180 patients with relapsing multiple sclerosis, an exacerbation occurred within the following 6 weeks in 33% after influenza illness, whereas it occurred in only 5% after vaccination. The exacerbation rate following influenza illness was significantly higher regardless of whether patients were essentially restricted to wheelchair or not. Because of a substantial greater risk of relapse after influenza illness than after vaccination, annual influenza vaccination should be offered routinely to all patients with relapsing multiple sclerosis.

Influenza

Influenza viruses are unique in their ability to cause recurrent epidemics and truly global pandemics during which acute febrile respiratory disease occurs explosively in all age groups. Epidemics of varying severity occur almost annually in temperate climates and are punctuated by the much less frequent but more dramatic occurrence of pandemic influenza. Increases in hospitalization and death often accompany widespread morbidity during influenza epidemics and pandemics. Influenza pandemics also threaten to disrupt other essential and nonessential services through high absenteeism, with high economic losses resulting. The medical impact and disruptive effects of epidemics and pandemics clearly justify careful global monitoring of influenza and strenuous efforts to prevent this emerging and reemerging disease.

[Influenza vaccines--routine and recent vaccines]

Current influenza vaccines in use at present are predominantly inactivated virus vaccines. The vaccines currently in use are designated whole-virus vaccines, split virus vaccines or subunit vaccines. In Europe, two new types of influenza vaccines have reached the commercial introduction. One is produced in Italy and uses the new adjuvant MF59 to enhance the immune response. The other type is produced in Switzerland and uses phosphatidyl choline (lecithin) liposomes as surface antigen carriers.

Is immunising all patients with chronic lung disease in the community against influenza cost effective? Evidence from a general practice based clinical prospective cohort study in Utrecht, The Netherlands

STUDY OBJECTIVE

There is little information on the potential benefit of immunising all patients with chronic lung disease in the community against influenza. The clinical effectiveness and economic benefit was established of the influenza vaccination programme in a general practice based cohort of adult patients with chronic lung disease followed up during the 1995/96 influenza A epidemic.

DESIGN

A prospective cohort study from October 1995 to March 1996.

SETTING

The study was undertaken in the Utrecht General Practices Network with six large group practices, covering a total population of approximately 50,000 patients in the Netherlands.

PATIENTS

Computerised medical records of 1696 patients with chronic lung disease aged over 18 years with an indication for vaccination according to the Dutch GP guidelines were reviewed.

MAIN RESULTS

The overall attack rate of any complication, including all cause death, low respiratory tract infection, and acute cardiac disease was 15%. Exacerbations of lung disease were most frequent (13%). Death, pneumonia, and acute cardiac disease were mainly limited to patients > or = 65 years. No effectiveness of the immunisation programme could be established in patients 18-64 years (n = 1066), after controlling for baseline prognosis in multivariable logistic regression analysis. In vaccinees > or = 65 years (n = 630), the occurrence of any complication was reduced by 50% (95% CI 17, 70%). The economic benefit was estimated at 50 Pounds per elderly vaccinee.

CONCLUSIONS

This study suggests that in the Netherlands immunisation of elderly patients with chronic lung disease against influenza is effective and cost-saving, hence these patients should be given high priority. More, preferably experimental, studies are needed to establish whether adult lung patients under 65 years in the community will also benefit from vaccination.

Systemic and local immune responses after parenteral influenza vaccination in juvenile diabetic patients and healthy controls: results from a pilot study

Diabetes patients suffer frequent complications and some excess mortality after influenza virus infection. Despite widespread agreement that diabetic patients should be routinely vaccinated against influenza, some reports claim that diabetics have a poor immune response to influenza vaccine. We have performed a pilot study to examine the humoral immune response of juvenile diabetics and matched healthy controls vaccinated with inactivated trivalent influenza vaccine. By enzyme-linked immunospot assay we found that both groups had comparable magnitude and kinetics of influenza-specific antibody secreting cell response. The influenza-specific antibody response in both serum and oral fluid were similar for both groups, and also showing a kinetic profile in accordance with our earlier data for healthy adults. Our study did not detect a difference in the humoral immune response between juvenile diabetics and healthy controls.

Influenza vaccination in 22 developed countries: an update to 1995

This study expands and updates through 1995 our earlier report on influenza vaccine use in 18 developed countries. Five of the six countries with high levels of vaccine use in 1992 (> or = 130 doses/1000 population) showed little change or slight declines over the subsequent 3 years. The exception was the United States, where a new federal program for vaccination reimbursement for the elderly helped to increase vaccine distribution from 144 to 239 doses/1000 population. The six countries with medium levels of vaccine use in 1992 (76-96 doses/1000 population) increased to > or = 100 doses/1000 population by 1995. Among the six low-use countries in 1992 (< or = 65 doses/1000 population), only Finland showed substantial improvement (96 doses/1000 population) in 1995. Four new countries were added to the study. In Germany, vaccine use increased to 80 doses/1000 population in 1995, but in Ireland it remained at a low level (48 doses/1000 population). In Korea, vaccine use increased from 17 to 95 doses/ 1000 population during the period 1987-1995. In Japan, very high levels of vaccine use (approximately 280 doses/1000 population) in the early 1980s were associated with vaccination programs for school children. However, vaccine use fell precipitously when these programs were discontinued, and only 2 and 8 doses/1000 population were used in 1994 and 1995, respectively. In all 22 countries, higher levels of vaccine use were associated with vaccination reimbursement programs under national or social health insurance and were not correlated with different levels of economic development. Excluding Japan, in 1995 there was still a greater than fourfold difference between the highest and lowest levels of vaccine use among the other 21 countries in the study. Given its well established clinical effectiveness and cost-effectiveness, none of these countries has yet achieved the full benefits of its programs for influenza vaccination.

Annually repeated influenza vaccination improves humoral responses to several influenza virus strains in healthy elderly

The benefit of annually repeated influenza vaccination on antibody formation is still under debate. In this study the effect of annually repeated influenza vaccination on haemagglutination inhibiting (HI) antibody formation in the elderly is investigated. Between 1990 and 1993 healthy young and elderly, both selected by the SENIEUR protocol, were vaccinated consecutively with commercially available influenza vaccines. The elderly had a lower HI antibody response after one vaccination as compared to the young against the A/Taiwan/1/86 (HINI), B/Yamagata/16/88 and B/Panama/45/90 strains. Annually repeated vaccination did not result in a decrease of the HI antibody titres against the A and B vaccine strains in both age groups. Moreover, the elderly had a significantly higher HI titre against the B strains after the second vaccination as compared to the first, resulting in comparable HI titres for young and elderly. Thus, annually repeated vaccination has a beneficial effect on the antibody titre against influenza virus and can contribute to a better antibody-response in the elderly.

The impact of vaccination strategy and methods of information on influenza and pneumococcal vaccination coverage in the elderly population

We compared the coverage achieved with either an age-based, free-of-charge vaccination program offering influenza vaccine alone or with pneumococcal vaccine with a restricted risk disease-based influenza vaccination program supplemented by self-funded immunization. We also compared two means of informing the public, either using mailed personal reminders or through the mass media only. Forty-one administrative districts with a total of 41,500 persons aged 65 years or older participated in the study during three consecutive seasons from 1992 to 1994. The average vaccination coverage achieved by the risk disease-based program was 20%, by the age-based program with mass media information, 52%, and by the age-based program with mailed personal reminders 82%. The availability of free-of-charge vaccines is thus not sufficient to ensure a high vaccination rate. The effect of the personal reminders was restricted to the year they were sent. The addition of pneumococcal vaccine to the age-based influenza vaccination program had little influence on the acceptance rate.

Influenza vaccination among healthy employees: a cost-benefit analysis

The cost of influenza vaccination and influenza infections was evaluated in a controlled study among healthy municipal homemakers. Acute respiratory infections were followed clinically and with laboratory samples for 8 months. Full follow-up was achieved in 351 persons in the intervention group, of whom 47% obtained vaccination, and 492 controls. Influenza infection was confirmed in 10 employees (8 of these in the control group) and other viral infections in 6 employees (5 of them controls). All infections occurred in non-vaccinated persons. The relative risk of infection in the control group was 2.9 (95% CI 0.6-13.4) for influenza and 3.1 (0.9-10.8) for all respiratory infections. The mean sick leave for influenza was 4.9 days. The cost per immunization was FIM 141, and the average cost per influenza infection FIM 1183. The cost per infection averted was FIM 6270, and the equivalent cost for immunization FIM 26.52. Influenza vaccination had a slight protective effect against both influenza and other respiratory infections. The cost of vaccination programmes exceeded the benefit from averted infections. Optimal vaccination strategies for healthy adults need to be planned individually with minimal loss of working time.

Risk factors for lower respiratory complications of rhinovirus infections in elderly people living in the community: prospective cohort study

OBJECTIVE

To assess the role of rhinoviruses in elderly people living in the community.

DESIGN

Prospective community based surveillance of elderly people, without intervention. Subjects were telephoned weekly to identify symptomatic upper respiratory tract infections. Symptoms and impact of illnesses were monitored, and specimens were collected for diagnostic serology and human rhinovirus polymerase chain reaction.

SETTING

Leicestershire, England.

SUBJECTS

533 subjects aged 60 to 90.

MAIN OUTCOME MEASURES

Symptoms, restriction of activity, medical consultations, and antibiotic use during 96 rhinovirus infections. Adjusted odds ratios for lower respiratory syndromes with respect to smoking and health status.

RESULTS

A viral cause was established in 211 (43%) of 497 respiratory illnesses; rhinoviruses were identified in 121 (24%) and as single pathogens in 107. The median duration of the first or only rhinovirus infection in the 96 people with 107 rhinovirus infections was 16 days; 18 of the 96 patients were confined to bed and 25 were unable to cope with routine household activities. Overall, 60 patients with rhinovirus infections had lower respiratory tract syndromes; 41 patients consulted their doctor, 31 of them (76%) receiving antibiotics. One patient died. Logistic regression analysis showed that chronic medical conditions increased the estimated probability of lower respiratory rhinovirus illness by 40% (95% confidence interval 17% to 68%) and smoking by 47% (14% to 90%). There were almost six times as many symptomatic rhinovirus infections as influenza A and B infections.

CONCLUSIONS

Rhinoviruses are an important cause of debility and lower respiratory illness among elderly people in the community. Chronic ill health and smoking increase the likelihood of lower respiratory complications from such infections. The overall burden of rhinovirus infections in elderly people may approach that of influenza.