Target Group For Vaccination Research Articles

Outbreak of Rift Valley fever affecting veterinarians and farmers in South Africa, 2008

During 2008, Rift Valley fever (RVF) virus re-emerged in South Africa as focal outbreaks in several provinces. To investigate an outbreak affecting cattle farmers and farm workers, and the staff and students of a veterinary school, assess the prevalence of infection during the outbreak, document the clinical presentation of cases, and identify potential risk factors. We conducted a cross-sectional serological survey of exposed veterinarians and farmers, who were examined to determine the presence of current or recent illness. Blood specimens were collected for virus isolation, nucleic acid detection and serology. A subset was interviewed using a standardised questionnaire to obtain data on recent exposures and risk factors for infection. Of 53 participants potentially exposed to infected domestic ruminants, 15% had evidence of recent infection and 4% evidence of past exposure to the RVF virus. The prevalence of acute infection was 21% in veterinarians compared with 9% in farmers and farm workers. After a mean incubation period of 4.3 days, the most frequent symptoms experienced included myalgia (100%), headache (88%) and malaise (75%). No asymptomatic cases were identified. Transmission, by direct contact with infected animals was the major risk factor in these professional groups. Performing animal autopsies was significantly associated with acute infection (risk ratio 16.3, 95% confidence interval 2.3 - 114.2). Increased risks associated with veterinary practices highlight a need for the use of personal protective equipment, and identify veterinarians as a primary target group for future vaccination.

Changing risk profile of hepatitis A in The Netherlands: a comparison of seroprevalence in 1995–1996 and 2006–2007

The prevalence of antibodies to hepatitis A virus (HAV) was assessed in a nationwide sample (n=6229) in The Netherlands in 2006-2007, and compared to the seroprevalence in a similar study in 1995-1996 (n=7376). The overall seroprevalence increased from 34% in 1995-1996 to 39% in 2006-2007, mainly due to vaccination of travellers and an increased immigrant population. Risk factors remain travelling to, and originating from, endemic regions, and vaccination is targeted currently at these risk groups. Our results show a trend of increasing age of the susceptible population. These people would also benefit from HAV vaccination because they are likely to develop clinically serious symptoms after infection, and are increasingly at risk of exposure through imported viruses through foods or travellers. The cost-effectiveness of adding elderly people born after the Second World War as a target group for prophylactic vaccination to reduce morbidity and mortality after HAV infection should be assessed.

New adjuvanted vaccines in pregnancy: what is known about their safety?

The recent introduction of oil-in-water emulsions as adjuvants in several pandemic vaccines, such as the H1N1 vaccine, has challenged regulatory authorities to establish their safety in the general population, as well as in specific populations. Pregnant women were advised to be a target group for H1N1 vaccination owing to the risk of this group developing serious complications with this infection. However, the addition of adjuvants to the H1N1 vaccine has initiated a discussion on the safety of adjuvanted vaccines in this special population. Changes in the maternal immune system are essential for acceptance of the fetus and for development of the placenta. The potential effects on pregnancy of interfering with this uniquely adapted immune balance through the induction of proinflammatory reactions such as those induced by adjuvanted vaccines have only been studied rarely. Here, we review the available information and discuss how vaccination may interfere with pregnancy, fetal development and pregnancy outcomes.

Healthcare workers as parents: attitudes toward vaccinating their children against pandemic influenza A/H1N1

BackgroundBoth the health care workers (HCWs) and children are target groups for pandemic influenza vaccination. The coverage of the target populations is an important determinant for impact of mass vaccination. The objective of this study is to determine the attitudes of HCWs as parents, toward vaccinating their children with pandemic influenza A/H1N1 vaccine.MethodsA cross-sectional questionnaire survey was conducted with health care workers (HCWs) in a public hospital during December 2009 in Istanbul. All persons employed in the hospital with or without a health-care occupation are accepted as HCW. The HCWs who are parents of children 6 months to 18 years of age were included in the study. Pearson's chi-square test and logistic regression analysis was applied for the statistical analyses.ResultsA total of 389 HCWs who were parents of children aged 6 months-18 years participated study. Among all participants 27.0% (n = 105) reported that themselves had been vaccinated against pandemic influenza A/H1N1. Two third (66.1%) of the parents answered that they will not vaccinate their children, 21.1% already vaccinated and 12.9% were still undecided. Concern about side effect was most reported reason among who had been not vaccinated their children and among undecided parents. The second reason for refusing the pandemic vaccine was concerns efficacy of the vaccine. Media was the only source of information about pandemic influenza in nearly one third of HCWs. Agreement with vaccine safety, self receipt of pandemic influenza A/H1N1 vaccine, and trust in Ministry of Health were found to be associated with the positive attitude toward vaccinating their children against pandemic influenza A/H1N1.ConclusionsPersuading parents to accept a new vaccine seems not be easy even if they are HCWs. In order to overcome the barriers among HCWs related to pandemic vaccines, determination of their misinformation, attitudes and behaviors regarding the pandemic influenza vaccination is necessary. Efforts for orienting the HCWs to use evidence based scientific sources, rather than the media for information should be considered by the authorities.

Influenza vaccination, pneumococcal vaccination and risk of acute myocardial infarction: matched case-control study

Previous studies have shown an association between acute myocardial infarction and preceding respiratory infection. Contradictory evidence exists on the influence of influenza vaccination and pneumococcal vaccination in preventing cardiovascular disease. We aimed to investigate the possible association of influenza vaccination and pneumococcal vaccination with acute myocardial infarction. We used a matched case-control design with data from the United Kingdom General Practice Research Database. Cases were patients who were at least 40 years of age at diagnosis of first acute myocardial infarction recorded from Nov.1, 2001, to May 31, 2007, and were matched for sex, general practice, age and calendar time (i.e., month corresponding to index date of acute myocardial infarction), with up to four controls each. Data were analyzed using conditional logistic regression, adjusted for vaccination target groups, cardiovascular risk factors, treatment medications and attendances at a general practice. We included 78 706 patients, of whom 16 012 were cases and 62 694 were matched controls. Influenza vaccination had been received in the previous year by 8472 cases (52.9%) and 32 081 controls (51.2%) and was associated with a 19% reduction in the rate of acute myocardial infarction (adjusted odds ratio [OR] 0.81, 95% confidence interval [CI] 0.77-0.85). Early seasonal influenza vaccination was associated with a lower rate of acute myocardial infarction (adjusted OR 0.79, 95% CI 0.75-0.83) than vaccination after mid-November (adjusted OR 0.88, 95% CI 0.79-0.97). Pneumococcal vaccination was not associated with a reduction in the rate of acute myocardial infarction (adjusted OR 0.96, 95% CI 0.91-1.02). Influenza vaccination but not pneumococcal vaccination is associated with a reduced rate of first acute myocardial infarction. This association and the potential benefit of early seasonal vaccination need to be considered in future experimental studies.

Committee Opinion No. 467: Human Papillomavirus Vaccination

The U.S. Food and Drug Administration has approved both a bivalent and quadrivalent human papillomavirus (HPV) vaccine. The Advisory Committee on Immunization Practices has recommended that HPV vaccination routinely be given to girls when they are 11 years or 12 years old. The vaccine can be given to individuals as young as 9 years; catch-up vaccination is recommended in females aged 13 years through 26 years. The American College of Obstetricians and Gynecologists endorses these recommendations. Although obstetrician-gynecologists are not likely to care for many girls in the initial vaccination target group, they are critical to the catch-up vaccination period. Both HPV vaccines are most effective if given before any exposure to HPV infection (ie, before sexual activity). However, sexually active girls and women can receive some benefit from the vaccination because exposure to all HPV types prevented by the vaccines is unlikely in females aged 13 years through 26 years. Vaccination with either HPV vaccine is not recommended for pregnant women. It can be provided to women who are breastfeeding. The need for booster vaccination has not been established but appears unnecessary. Health care providers are encouraged to discuss with their patients the benefits and limitations of the HPV vaccine and the need for routine cervical cytology screening for those aged 21 years and older.

Risk groups and other target groups – preliminary ECDC guidance for developing influenza vaccination recommendations for the season 2010-11

Providing guidance on risk and target groups for seasonal influenza immunisation is difficult for the 2010-11 season since there is no experience with the new influenza A(H1N1) virus in its seasonal form. Arguments exist for offering immunisation to people with chronic illness and older people, and also for other risk and target groups including pregnant women. A more rigorous approach is being developed to produce annual evidence-based guidance on risk and target groups for influenza vaccination.

Measles outbreaks in displaced populations: a review of transmission, morbidity and mortality associated factors.

BackgroundMeasles is a highly contagious infectious disease with a significant public health impact especially among displaced populations due to their characteristic mass population displacement, high population density in camps and low measles vaccination coverage among children. While the fatality rate in stable populations is generally around 2%, evidence shows that it is usually high among populations displaced by disasters. In recent years, refugees and internally displaced persons have been increasing. Our study aims to define the epidemiological characteristics and risk factors associated with measles outbreaks in displaced populations.MethodsWe reviewed literature in the PubMed database, and selected articles for our analysis that quantitatively described measles outbreaks.ResultsA total of nine articles describing 11 measles outbreak studies were selected. The outbreaks occurred between 1979 and 2005 in Asia and Africa, mostly during post-conflict situations. Seven of eight outbreaks were associated with poor vaccination status (vaccination coverage; 17-57%), while one was predominantly due to one-dose vaccine coverage. The age of cases ranged from 1 month to 39 years. Children aged 6 months to 5 years were the most common target group for vaccination; however, 1622 cases (51.0% of the total cases) were older than 5 years of age. Higher case-fatality rates (>5%) were reported for five outbreaks. Consistent factors associated with measles transmission, morbidity and mortality were vaccination status, living conditions, movements of refugees, nutritional status and effectiveness of control measures including vaccination campaigns, surveillance and security situations in affected zones. No fatalities were reported in two outbreaks during which a combination of active and passive surveillance was employed.ConclusionMeasles patterns have varied over time among populations displaced by natural and man-made disasters. Appropriate risk assessment and surveillance strategies are essential approaches for reducing morbidity and mortality due to measles. Learning from past experiences of measles outbreaks in displaced populations is important for designing future strategies for measles control in such situations.

Incidence of 2009 pandemic influenza A H1N1 infection in England: a cross-sectional serological study

Knowledge of the age-specific prevalence of immunity from, and incidence of infection with, 2009 pandemic influenza A H1N1 virus is essential for modelling the future burden of disease and the effectiveness of interventions such as vaccination. In this cross-sectional serological survey, we obtained 1403 serum samples taken in 2008 (before the first wave of H1N1 infection) and 1954 serum samples taken in August and September, 2009 (after the first wave of infection) as part of the annual collection for the Health Protection Agency seroepidemiology programme from patients accessing health care in England. Antibody titres were measured by use of haemagglutination inhibition and microneutralisation assays. We calculated the proportion of samples with antibodies to pandemic H1N1 virus in 2008 by age group and compared the proportion of samples with haemagglutination inhibition titre 1:32 or more (deemed a protective response) before the first wave of infection with the proportion after the first wave. In the baseline serum samples from 2008, haemagglutination inhibition and microneutralisation antibody titres increased significantly with age (F test p<0.0001). The proportion of samples with haemagglutination inhibition titre 1:32 or more ranged from 1.8% (three of 171; 95% CI 0.6-5.0) in children aged 0-4 years to 31.3% (52 of 166; 24.8-38.7) in adults aged 80 years or older. In London and the West Midlands, the difference in the proportion of samples with haemagglutination inhibition titre equal to or above 1:32 between baseline and September, 2009, was 21.3% (95% CI 8.8-40.3) for children younger than 5 years of age, 42.0% (26.3-58.2) for 5-14-year-olds, and 20.6% (1.6-42.4) for 15-24-year-olds, with no difference between baseline and September in older age groups. In other regions, only children younger than 15 years showed a significant increase from baseline (6.3%, 1.8-12.9). Around one child in every three was infected with 2009 pandemic H1N1 in the first wave of infection in regions with a high incidence, ten times more than estimated from clinical surveillance. Pre-existing antibody in older age groups protects against infection. Children have an important role in transmission of influenza and would be a key target group for vaccination both for their protection and for the protection of others through herd immunity. National Institute for Health Research Health Technology Assessment Programme.

U.S. Prepares H1N1 Vaccine Strategy

U.S. Prepares H1N1 Vaccine Strategy

Seroprevalence of mumps before inclusion of mumps vaccination in the Iranian Expanded Programme on Immunization

The current target groups for measles, mumps and rubella vaccination in the Islamic Republic of Iran are children at 12 months and 4-6 years. A study of the age-specific seroprevalenceRepublic of Iran are children at 12 months and 4-6 years. A study of the age-specific seroprevalence of antibodies against mumps in children aged 3-18 years in Shahrekord aimed to establish the needof antibodies against mumps in children aged 3-18 years in Shahrekord aimed to establish the need for booster vaccinations to cover non-immune children. Of 338 children, 19.8% were seronegative. Age-specific seronegativity was 33.3%, 20.5% and 4.6% in age groups 7-11, 12-14 and 15-18 years respectively. To obtain herd immunity, we suggest that for the next 5 years children aged 7-11 years entering guidance school are selected as the main group for vaccination.

Special Edition: Editorial

It is surprising that over 60 years have elapsed since the first use of influenza vaccines, yet with the advances in biotechnology that have occurred in the interim, the majority of the influenza vaccines that we use today are still non‐living viral antigens produced in a relatively uncontrolled substrate, the embryonated chicken egg. It is also surprising that the impact of seasonal influenza has only gradually entered the consciousness of public health authorities over the last couple of decades. This has resulted in expanded national recommendations for influenza vaccination and gradually increasing vaccine use, at least in many of the more economically developed and rapidly developing countries. 1 , 2 It has been widely accepted for many years that a future influenza pandemic is inevitable. Regardless of the development of new influenza‐specific antivirals, vaccines are seen as the most effective response against such a threat and, therefore, have a key role in pandemic preparedness planning. It is quite alarming, then, that the current global capacity to produce vaccine would fall woefully short of global needs in the event of a pandemic that occurred today. 3 , 4 One of the few significant ‘improvements’ introduced into vaccine manufacture was a move to sub‐virion vaccines in order to reduce the reactogenicity that was observed principally when administered to infants and young children. 5 Ironically, this was clearly demonstrated in the late 1970s to reduce vaccine immunogenicity in immunologically naive individuals, 6 , 7 , 8 as would be the case in a pandemic. Other studies have also shown reduced immunogenicity of seasonal sub‐virion vaccine in the older adult, a major target group for annual vaccination. 9 Another improvement, the immunological standardization of vaccine antigen content, 10 , 11 might, in itself, contribute to delays in vaccine availability due to the time required to produce the required reagents. The ongoing epizootic of avian influenza due to A(H5N1) viruses, and the growing count of associated human fatalities, has stimulated the development of candidate pandemic vaccines with an emphasis on the H5 subtype. 12 All of the initial human studies with H5 vaccines suggested that the haemagglutinin of this subtype displayed an immunogenicity that was lower than that of the haemagglutinins of other candidate pandemic viruses, such as H2 and H9 13 , 14 , 15 which has compounded the shortcomings of the current sub‐virion vaccines and further reduces the potential pandemic vaccine supply. This has stimulated a variety of approaches to resolving this issue including new ways of producing vaccine antigen, improving immunogenicity by the use of existing and new immunological adjuvants and even a return to the use of whole virus preparations. A number of encouraging results that offer the possibility of improving the quantity and potency of A(H5N1) vaccines within the immediate future have recently been reported. In view of their importance to those involved in public health programmes and pandemic preparedness planning it is important to record as many of these as possible in a single publication. We have, therefore, canvassed widely among vaccine manufacturers and developers for up‐to‐date review articles describing their improved products for seasonal and/or pandemic influenza. Although not all have contributed there has been an excellent response and the journal is pleased to publish these articles in this special edition.

Coverage and predictors of influenza vaccination among adults living in a large metropolitan area in Spain: A comparison between the immigrant and indigenous populations

This study sought to evaluate influenza vaccination coverage in Madrid (Spain). Coverages were estimated for vaccine target groups and special attention was placed on the immigrant population. Individual data from 7341 adults included in the Madrid City Health Survey conducted in 2005 was used. Overall influenza vaccination coverage was 24%. Compliance with age-based influenza vaccine guidelines (≥65 years) was 63.9%, among those <65 years who had an associated chronic condition, it was 37.9% and 24.1% among HCWs. Immigrants accounted for 12.4% of the sample. Overall crude coverage was significantly lower among immigrants than among the indigenous population (11.2% vs. 25.9%), but once the multivariate analysis had been performed, the association became non-significant. In conclusion, it must be said that all the available evidence indicates an inadequate level of influenza vaccination coverage among HCWs and high-risk subjects <65 years. On the other hand, coverages among subjects aged ≥65 years are acceptable and there is no observable difference in vaccine use between immigrants and indigenous subjects. Strategies that have demonstrated their effectiveness in enhancing vaccination coverages should be applied in Madrid.

Cytomegalovirus Disease Amongst Renal Transplant Recipients in Australia and New Zealand

Cytomegalovirus (CMV) is a significant pathogen causing disease in renal transplant patients. The highest incidence of CMV disease occurs during the first 3 months post-transplant and is most problematic in CMV-naïve transplant recipients. In this study, we conducted a retrospective review of two databases, the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) and the National Hospital Morbidity Database, from the Australian Institute of Health and Welfare (AIHW), to examine CMV in renal transplant recipients. The first source looked at CMV serostatus at the time of transplantation and the second recorded hospital admissions for recipients with invasive CMV disease.From the ANZDATA registry, we obtained information from 13,530 renal transplants recipients from 1980 to 2004. Of these recipients, 7808 had a known CMV serostatus, of which 65.7% (5134/7808) had a positive sero antibody status and 34.2% (2674/7808) had a negative sero antibody status. In univariate analysis, factors significantly associated with renal rejection were being male, recipient age &lt;50 years, being diabetic, being diagnosed with cancer at some point and having a positive EBV status. Positive CMV serostatus was not a contributing factor. Between 1993 and 2001 there were 1445 renal transplant recipients hospitalized in Australia with a diagnosis of CMV disease, of which 38% (554/1445) had CMV disease as a principal diagnoses. The average annual rate of admissions with any diagnosis was 3871 episodes per 100,000 people living with a functioning graft.Preventative strategies for CMV in renal transplant recipients should be a priority. New vaccines for CMV may soon be available and renal transplant recipients would be a suitable target group for vaccination.

Studio costo-efficacia della vaccinazione influenzale per gli italiani di età compresa tra 50 e 64 anni

Background In 1999, the American Academy of Family Physicians already included, among target groups for influenza vaccination, subjects aged 50–64 years, because of the increased prevalence of people with high-risk conditions in this age group. However, studies on the cost-effectiveness and cost-utility of influenza vaccination in this population are necessary in order to provide useful indications for Public Health decision makers.

Target groups for influenza vaccination

Target groups for influenza vaccination

Establishing the health and economic impact of influenza vaccination within the European Union 25 countries

Background In 2003, the World Health Assembly (WHA) issued a resolution for prevention and control of influenza pandemics and annual epidemics, which urges the European Union 25 (EU-25) Member States to (1) establish and implement strategies to increase vaccination coverage of all people at high risk, including the elderly and people with underlying disease, with the goal of attaining vaccination coverage of the elderly population of at least 50% by 2006 and 75% by 2010; (2) to assess the disease burden and economic impact of annual influenza epidemics as a basis for framing and implementing influenza prevention policies. This resolution was reinforced by the European Union (EU), where Member States agreed to make additional efforts to improve uptake on their territory in accordance with their own recommendations and to achieve the World Health Organisation (WHO) target of 75% in high risk groups before 2010. It was also noted that the changing demographic profile of the EU population would result in an increasing number of elderly people falling within the current target groups. Objectives To establish the number of people who may be eligible for influenza vaccination in the EU, and estimate the costs and consequences of not vaccinating this population for five EU Member States, France, Germany, Italy, Spain, and the UK. Methods A mathematical model has previously been developed, in which vaccine distribution data are combined with demographic and health economics data to model the public health consequences of influenza and possible intervention strategies. We have extended that model using specific EU-25 demographic data on populations at risk of influenza during the inter-pandemic period. For each country, the total population and age breakdown was calculated to estimate the percentage of the population that falls under the WHA recommendations. Other target groups for influenza vaccination were identified by analysing estimating the proportion of the population with respiratory or cardiovascular related diseases, diabetes, AIDS or transplantation, as well as health care professionals. Target population size and possible vaccination coverage rates across the EU-25 Member States, along with the potential cost and health consequence impact is estimated. Results For the EU-25, it was estimated that up to 49.1% of the population (or 223.4 million people) should be vaccinated against influenza. This ranged from 41.6% in Cyprus to 56.4% in the UK. There were, on average, 174 vaccine doses distributed per 1000 population within the EU-25, which leads to an average vaccination rate of the target population of 35.4% based on current supply constraints. As a consequence, up to 144.4 million people who could be considered “at risk” may not currently be vaccinated. Implementing a 100% vaccination rate programme for all risk groups across the EU-25 would lead to an estimated reduction of number of influenza cases of 7.22 million, 1.96 million reduced PCP visits for influenza treatment, 796,743 less hospital admissions and 68,537 fewer influenza related deaths for all EU-25 countries. The implementation of a 100% vaccination rate programme for all risk groups in France, Germany, Italy, Spain and UK would require an additional €1.52 billion. This would result in estimated savings of €39.45 million of reduced primary care visits and further savings of €1.59 billion in reduced hospitalisations respectively in these countries. Conclusions There is a gap between current vaccination coverage and the EU recommendations. The public health consequences of low vaccination coverage include increased morbidity, hospitalisations and mortality associated with influenza-related complications. This model is a powerful tool to: (1) support EU public health officials in implementing recommendations; (2) to visualize the need for increased vaccination rates for better influenza control; (3) the consequences of low vaccine coverage.

Using Healthcare Administrative Data to Identify High Priority Target Groups for Influenza Vaccination

Using Healthcare Administrative Data to Identify High Priority Target Groups for Influenza Vaccination

Influenza-attributable mortality among the elderly in Switzerland.

Influenza infections are considered responsible for a substantial burden of disease and mortality in the elderly, especially during winter time. However, death certificates indicating influenza as the cause of death might only partly reflect the mortality attributable to influenza. We estimated influenza-attributable mortality for the Swiss resident population of age 60 and older from 1969 to 1999 by Poisson regression modelling of all cause and influenza mortality, and examined long-term trends by age and gender. In sensitivity analyses we additionally used data on official pneumonia deaths, as well as clinical diagnosis of influenza-associated illnesses from the Swiss Sentinel Network. For the 30 successive respiratory seasons (July of a given year to June of the next year) from 1969/70 to 1998/99 the estimated total number of influenza-attributable deaths in the Swiss population of 60+ was 24 800 (95% confidence interval: 21 000 to 28 600), about 2 times the official count of influenza deaths. Influenza-attributable mortality rate declined from 1969 to 1999, but the yearly number of influenza-attributable deaths nevertheless stabilised at around 600 to 700 in the ninety's due to aging of the population. The oldest-aged groups persistently showed the highest influenza mortality rate. Influenza-attributable mortality estimates were substantially higher when using the general practice influenza indicator (by 66%) or the combined cause-of-death category pneumonia and influenza (by 169%). Only counting official influenza deaths underestimated influenza-attributable mortality in Switzerland by a factor of two to three. Despite a gradual decline in age-specific influenza attributable mortality rates in the years 1969 to 1999, we estimated an average annual number of 830 deaths in the elderly Swiss resident population. The elderly remain the primary target group for influenza vaccination to reduce influenza-attributable mortality.

Influenza-attributable mortality among the elderly in Switzerland.

Influenza infections are considered responsible for a substantial burden of disease and mortality in the elderly, especially during winter time. However, death certificates indicating influenza as the cause of death might only partly reflect the mortality attributable to influenza. We estimated influenza-attributable mortality for the Swiss resident population of age 60 and older from 1969 to 1999 by Poisson regression modelling of all cause and influenza mortality, and examined long-term trends by age and gender. In sensitivity analyses we additionally used data on official pneumonia deaths, as well as clinical diagnosis of influenza-associated illnesses from the Swiss Sentinel Network. For the 30 successive respiratory seasons (July of a given year to June of the next year) from 1969/70 to 1998/99 the estimated total number of influenza-attributable deaths in the Swiss population of 60+ was 24 800 (95% confidence interval: 21 000 to 28 600), about 2 times the official count of influenza deaths. Influenza-attributable mortality rate declined from 1969 to 1999, but the yearly number of influenza-attributable deaths nevertheless stabilised at around 600 to 700 in the ninety's due to aging of the population. The oldest-aged groups persistently showed the highest influenza mortality rate. Influenza-attributable mortality estimates were substantially higher when using the general practice influenza indicator (by 66%) or the combined cause-of-death category pneumonia and influenza (by 169%). Only counting official influenza deaths underestimated influenza-attributable mortality in Switzerland by a factor of two to three. Despite a gradual decline in age-specific influenza attributable mortality rates in the years 1969 to 1999, we estimated an average annual number of 830 deaths in the elderly Swiss resident population. The elderly remain the primary target group for influenza vaccination to reduce influenza-attributable mortality.