Trends in influenza vaccination coverage in Portugal from 1998 to 2010: effect of major pandemic threats

Abstract

BackgroundVaccination is the key measure available for prevention of the public health burden of annual influenza epidemics. This article describes national trends in seasonal influenza vaccine (IV) coverage in Portugal from 1998/99 to 2010/11, analyzes progress towards meeting WHO 2010 coverage goals, and addresses the effect of major public health threats of the last 12 years (SARS in 2003/04, influenza A (H5N1) in 2005/06, and the influenza A (H1N1)2009 pandemic) on vaccination trends.MethodsThe National Institute of Health surveyed (12 times) a random sample of Portuguese families. IV coverage was estimated and was adjusted for age distribution and country region. Independence of age and sex coverage distribution was tested using a modified F-statistic with a 5% significance level. The effect of SARS, A (H5N1), and the A (H1N1)2009 pandemic was tested using a meta-regression model. The model was adjusted for IV coverage in the general population and in the age groups.ResultsBetween 1998/99 and 2010/11 IV, coverage in the general population varied between 14.2% (CI 95%: 11.6%–16.8%) and 17.5% (CI 95%: 17.6%–21.6%). There was no trend in coverage (p = 0.097). In the younger age group (<15 years) a declining trend was identified until 2008/09 (p = 0.005). This trend reversed in 2009/10. There was also a gradual and significant increase in seasonal IV coverage in the elderly (p for trend < 0.001). After 2006/07, IV coverage remained near 50%. Adjusting for baseline trends, there was significantly higher coverage in the general population in 2003/04 (p = 0.032) and 2005/06 (p = 0.018). The high coverage observed in the <15-year age group in season 2009/10 was also significant (p = 0.015).ConclusionsIV coverage in the elderly population displayed an increasing trend, but the 75% WHO 2010 target was not met. This result indicates that influenza vaccination strategy should be improved to meet the ambitious WHO coverage goals. The major pandemic threats of the past decade had a modest but significant effect on seasonal influenza vaccination. There was an increase in vaccine uptake proportion in the general population in 2003/04 and in 2005/06, and in individuals <15 years old in 2009/10.

Beliefs and attitudes towards the influenza vaccine in high-risk individuals

“…It is important to keep in mind that perceptions may change over time, because risk assessment is embedded in social and cultural contexts [31] and the study cross-sectional nature hampers results generalisation for different time periods. Second, the problem of information bias applies to both the chronic disease and the vaccine uptake questions, which were self-reported [23]. Furthermore, the questionnaire employed to assess HBM dimensions was not validated in the Portuguese population, which can pose validity issues, specifically when assessing misconceptions.…”

“…The items were adapted from previous instruments and statements specifically tailored to evaluate influenza vaccine acceptance among older adults (60 years and over) [12–15, 23]. An open question aimed only at non-vaccinated high-risk individuals was also included: ‘What was the main reason for not being vaccinated against the flu in the last season?’.…”

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

“…The influenza vaccine coverage (IVC) rates, for individuals with 65 and more years, were obtained from ECOS (Em Casa Observamos Saúde—At Home We Watch Health), a panel of approximately 1000 households on which a seasonal survey is carried out by computer‐assisted telephone interview (CATI) . These households were selected randomly from the national telephone directory and recruited considering the representativeness of Portuguese mainland families reachable by telephone.…”

Influenza vaccination among Saudi Hajj pilgrims: Revealing the uptake and vaccination barriers

“…Variation in vaccination coverage across countries and years may be partially explained by the influence of pandemics and other outbreaks on vaccination uptake. Notable non-Hajj outbreaks such as SARS in 2003-04 and avian influenza (H5N1) in 2005-06 contributed to a relative increase in influenza vaccination uptake in several settings [46][47][48][49]. Similarly, the highest influenza vaccine uptake among Hajj pilgrims from different countries was observed in 2009 during the global outbreak of influenza A(H1N1)pdm 2009 strain [14,15,27].…”