Narcolepsy and hypersomnia in Norwegian children and young adults following the influenza A(H1N1) 2009 pandemic

BackgroundAssociations between influenza infection and sleep disorders are poorly studied. We investigated if pandemic influenza infection or vaccination with Pandemrix in 2009/2010 was associated with narcolepsy or hypersomnia in children and young adults.MethodsWe followed the Norwegian population under age 30 from January 2008 through December 2012 by linking national health registry data. Narcolepsy diagnoses were validated using hospital records. Risks of narcolepsy or hypersomnia were estimated as adjusted hazard ratios (HRs) in Cox regression models with influenza infection and vaccination as time-dependent exposures.ResultsAmong the 1,638,526 persons under age 30 in Norway in 2009, 3.6% received a physician diagnosis of influenza during the pandemic, while 41.9% were vaccinated against pandemic influenza. Between October 1st 2009 and December 31st 2012, 72 persons had onset of narcolepsy and 305 were diagnosed with hypersomnia. The risk of a sleep disorder was associated with infection during the first six months, adjusted HR 3.31 with 95% confidence interval [CI], 1.01–10.79 for narcolepsy and adjusted HR 3.13 (95% CI, 1.12–8.76) for hypersomnia. The risk of narcolepsy was strongly associated with vaccination during the first six months adjusted HR 17.21 (95% CI, 6.28–47.14), while the adjusted HR for hypersomnia was 1.54 (95% CI, 0.81–2.93).ConclusionsThe study confirms an increased HR of narcolepsy following pandemic vaccination. Slightly increased HRs of narcolepsy and hypersomnia are also seen after influenza infection. However, the role of infection should be viewed with caution due to underreporting of influenza.     

Accounting for personal and professional choices for pandemic influenza vaccination amongst English healthcare workers

BackgroundHealthcare workers (HCWs) are encouraged to get vaccinated during influenza pandemics to reduce their own, and patients’, risk of infection, and to encourage their patients to get immunised. Despite extensive research on HCWs’ receipt of vaccination, little is known about how HCWs articulate pandemic influenza vaccination advice to patients.AimsTo explore HCWs’ uptake of the A/H1N1 vaccine during the pandemic of 2009–2010, their recommendations to patients at the time, and their anticipated choices around influenza vaccination under different pandemic scenarios.MethodWe conducted semi-structured interviews and focus groups with eight vaccinated and seventeen non-vaccinated HCWs from primary care practices in England. The data was analysed using thematic analysis.ResultsThe HCWs constructed their receipt of vaccination as a personal choice informed by personal health history and perceptions of vaccine safety, while they viewed patients’ vaccination as choices made following informed consent and medical guidelines. Some HCWs received the A/H1N1 vaccine under the influence of their local practice organizational norms and values. While non-vaccinated HCWs regarded patients’ vaccination as patients’ choice, some vaccinated HCWs saw it also as a public health issue. The non-vaccinated HCWs emphasised that they would not allow their personal choices to influence the advice they gave to patients, whereas some vaccinated HCWs believed that by getting vaccinated themselves they could provide a reassuring example to patients, particularly those who have concerns about influenza vaccination. All HCWs indicated they would accept vaccination under the severe pandemic scenario. However, most non-vaccinated HCWs expressed reticence to vaccinate under the mild pandemic scenario.ConclusionsProviding evidence-based arguments about the safety of new vaccines and the priority of public health over personal choice, and creating strong social norms for influenza vaccination as part of the organizational culture, should increase uptake of influenza vaccination among primary care HCWs and their patients.     

Knowledge and attitude of Kenyan healthcare workers towards pandemic influenza disease and vaccination: 9 years after the last influenza pandemic

BackgroundHealthcare workers (HCWs) are at high risk of exposure and transmission of infectious respiratory pathogens like influenza. Despite the potential benefits, safety and efficacy of influenza vaccination, vaccines are still underutilized in Africa, including among HCWs.MethodFrom May-June 2018, we conducted a cross-sectional, self-administered, written survey among HCWs from seven counties in Kenya and assessed their knowledge attitudes and perceptions towards pandemic influenza disease and vaccination. Using regression models, we assessed factors that were associated with the HCW’s knowledge of pandemic influenza and vaccination.ResultsA total of 2,035 HCWs, representing 49% of the targeted respondents from 35 health facilities, completed the question. Sixty eight percent of the HCWs had ever heard of pandemic influenza, and 80.0% of these were willing to receive pandemic influenza vaccine if it was available. On average, Kenyan HCWs correctly answered 55.0% (95% CI 54.0–55.9) of the questions about pandemic influenza and vaccination. Physicians (65.6%, 95% CI 62.5–68.7) and pharmacists (61.7%, 95% CI 57.9–65.5) scored higher compared to nurses (53.1%, 95% CI 51.7–54.5). HCWs with 5 or more years of work experience (55.8, 95% CI 54.5–57.0) had marginally higher knowledge scores compared to those with less experience (53.9%, 95% CI 52.5–55.3). Most participants who were willing to receive pandemic influenza vaccine did so to protect their relatives (88.7%) or patients (85.9%).ConclusionOur findings suggest moderate knowledge of pandemic influenza and vaccination by HCWs in Kenya, which varied by cadre and years of work experience. These findings highlight the need for continued in-service health education to increase the HCW’s awareness and knowledge of pandemic influenza to increase acceptance of influenza vaccination in the case of a pandemic.     

HPV vaccination and risk of chronic fatigue syndrome/myalgic encephalomyelitis: A nationwide register-based study from Norway

BackgroundVaccination has been suggested to be involved in the aetiology of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). HPV vaccine was introduced in the Norwegian Childhood Immunisation Programme and offered 12 year old girls from 2009. We studied the association between HPV vaccination and risk of CFS/ME and also assessed medical history in relation to both risk of CFS/ME and HPV vaccine uptake.MethodsIndividual data from national registries, including the Norwegian Population Registry, the Norwegian Patient Registry and the Norwegian Immunisation Registry were linked using the unique personal identification number. Yearly incidence rates of CFS/ME for 2009–2014 were calculated among the 824,133 boys and girls, aged 10–17 living in Norway during these 6 years. A total of 176,453 girls born 1997–2002 were eligible for HPV vaccination and included in further analyses. Hazard ratios (HRs) of CFS/ME were estimated using Cox regression. Risk differences (RDs) of vaccine uptake were estimated with binomial regression.ResultsA similar yearly increase in incidence rate of CFS/ME was observed among girls and boys, IRR = 1.15 (95% confidence interval (CI) 1.10–1.19) and 1.15 (95% CI 1.09–1.22), respectively. HPV vaccination was not associated with CFS/ME, HR = 0.86 (95% CI 0.69–1.08) for the entire follow-up period and 0.96 (95% CI 0.64–1.43) for the first two years after vaccination. The risk of CFS/ME increased with increasing number of previous hospital contacts, HR = 5.23 (95% CI 3.66–7.49) for 7 or more contacts as compared to no contacts. Girls with 7 or more hospital contacts were less likely to be vaccinated than girls with no previous hospital contacts, RD = −5.5% (95% CI −6.7% to −4.2%).ConclusionsNo indication of increased risk of CFS/ME following HPV vaccination was observed among girls in the first 6 birth cohorts offered HPV vaccine through the national immunisation programme in Norway.     

Hospitalization following influenza infection and pandemic vaccination in multiple sclerosis patients: a nationwide population-based registry study from Norway

Patients with multiple sclerosis (MS) are at increased risk of infections and related worsening of neurological function. Influenza infection has been associated with increased risk of various neurological complications. We conducted a population-based registry study to investigate the risk of acute hospitalization of MS patients in relation to influenza infection or pandemic vaccination in Norway. The entire Norwegian population in the years 2008–2014 was defined as our study population (N = 5,219,296). Information on MS diagnosis, influenza infection and vaccination were provided by Norwegian national registries. The self-controlled case series method was used to estimate incidence rate ratios (IRRs) with 95% confidence intervals (95% CI) in defined risk periods. 6755 MS patients were identified during the study period. Average age at first registration of an MS diagnosis was 51.8 years among men and 49.9 years among females (66.9%). The IRR for emergency hospitalization among MS patients the first week after an influenza diagnosis was 3.4 (95% CI 2.4–4.8). The IRR was 5.6 (95% CI 2.7–11.3) after pandemic influenza, and 4.8 (95% CI 3.1–7.4) after seasonal influenza. Pandemic vaccination did not influence risk of hospitalization [IRR within the first week: 0.7 (95% CI 0.5–1.0)]. Among MS patients, influenza infection was associated with increased risk for acute hospitalization while no increased risk was observed after pandemic vaccination. Influenza vaccination could prevent worsening of MS-related symptoms as well as risk of hospitalization.     

Parental socioeconomic and psychological determinants of the 2009 pandemic influenza A(H1N1) vaccine uptake in children

BackgroundBefore COVID-19, the previous pandemic was caused by influenza A(H1N1)pdm09 virus in 2009. Identification of factors behind parental decisions to have their child vaccinated against pandemic influenza could be helpful in planning of other pandemic vaccination programmes. We investigated the association of parental socioeconomic and psychosocial factors with uptake of the pandemic influenza vaccine in children in 2009–2010.MethodsThis study was conducted within a prospective birth-cohort study (STEPS Study), where children born in 2008–2010 are followed from pregnancy to adulthood. Demographic and socioeconomic factors of parents were collected through questionnaires and vaccination data from electronic registers. Before and after the birth of the child, the mother’s and father’s individual and relational psychosocial well-being, i.e. depressive symptoms, dissatisfaction with the relationship, experienced social and emotional loneliness, and maternal anxiety during pregnancy, were measured by validated questionnaires (BDI-II, RDAS, PRAQ, and UCLA).ResultsOf 1020 children aged 6–20 months at the beginning of pandemic influenza vaccinations, 820 (80%) received and 200 (20%) did not receive the vaccine against influenza A(H1N1)pdm09. All measures of parents’ psychosocial well-being were similar between vaccinated and non-vaccinated children. Children of younger mothers had a higher risk of not receiving the influenza A(H1N1)pdm09 vaccine than children of older mothers (OR 2.59, 95% CI 1.52–4.43, for mothers < 27.7 years compared to ≥ 33.6 years of age). Children of mothers with lower educational level had an increased risk of not receiving the vaccine (OR 1.46, 95% CI 1.00–2.14).ConclusionsMother’s younger age and lower education level were associated with an increased risk for the child not to receive the 2009 pandemic influenza vaccine, but individual or relational psychosocial well-being of parents was not associated with children’s vaccination. Our findings suggest that young and poorly educated mothers should receive targeted support in order to promote children’s vaccinations during a pandemic.     

High effectiveness of pandemic influenza A (H1N1) vaccination in healthcare workers from a Portuguese hospital

Objectives

Vaccination of healthcare workers (HCWs) was made a high priority during the phase six pandemic of the novel influenza A H1N1 (pH1N1) virus. We surveyed adherence to pH1N1 vaccination and the incidence of pH1N1 infection between vaccinated and unvaccinated HCWs.

Methods

Employees at the S. Jo?o Hospital in Porto, Portugal, were offered pH1N1 vaccinations free of charge. Pandemrix^? was the vaccine administered. As part of the pandemic plan, employees with influenza-like symptoms (ILS) were called upon to take an RT-PCR H1N1 test. If the test results were positive, they had to stay off work for at least 7?days. Sociodemographic data, vaccination status, contact with infectious patients, ILS and pH1N1 test results were documented in a standardised manner.

Results

The survey population comprised 5,592 employees. The vaccination rate was 30.8% (n?=?1,720) for pH1N1 and 50.4% (n?=?2,819) for the 2009/2010 seasonal trivalent inactivated influenza vaccine (TIV). One mild anaphylactic reaction occurred after pH1N1 vaccination. Minor local side effects occurred more often after pH1N1 vaccination than after 2009/2010 seasonal TIV (38.0% vs. 12.3%). Pandemic H1N1 infection was diagnosed in 97 HCWs (1.7%). Compared to employees with no regular patient contact, nurses (2.8%) had the highest risk of pH1N1 infection (adjusted OR 3.8; 95% CI 1.2–6.8). Vaccination reduced the pH1N1 infection risk (OR 0.12; 95% CI 0.05–0.29). Vaccine effectiveness was 90.4% (95% CI 73.5–97.3%).

Conclusion

Vaccination reduced the pH1N1 infection risk considerably. The pandemic plan to contain the pH1N1 infection was successful. Nurses had the highest risk of pH1N1 infection and are therefore a target group for vaccination measures.     

Factors associated with uptake of vaccination against pandemic influenza: a systematic review

Background

In June 2009 a global influenza pandemic was declared by the World Health Organisation. A vaccination programme against H1N1 influenza was introduced in many countries from September 2009, but there was low uptake in both the general population and health professionals in many, though not all, countries.

Purpose

To examine the psychological and demographic factors associated with uptake of vaccination during the 2009 pandemic.

Method

A systematic literature review searching Web of Science and PubMed databases up to 24 January 2011.

Results

37 articles met the study inclusion criteria. Using the framework of Protection Motivation Theory the review found that both the degree of threat experienced in the 2009 pandemic influenza outbreak and perceptions of vaccination as an effective coping strategy were associated with stronger intentions and higher uptake of vaccination. Appraisal of threat resulted from both believing oneself to be at risk from developing H1N1 influenza and concern and worry about the disease. Appraisal of coping resulted from concerns about the safety of the vaccine and its side effects. There was evidence of an influence of social pressure in that people who thought that others wanted them to be vaccinated were more likely to do so and people getting their information about vaccination from official health sources being more likely to be vaccinated than those relying on unofficial sources. There was also a strong influence of past behaviour, with those having been vaccinated in the past against seasonal influenza being more likely to be vaccinated against pandemic influenza. Demographic factors associated with higher intentions and uptake of vaccination were: older age, male gender, being from an ethnic minority and, for health professionals, being a doctor.

Discussion

Interventions designed to increase vaccination rates could be developed and implemented in advance of a pandemic. Strategies to improve uptake of vaccination include interventions which highlight the risk posed by pandemic influenza while simultaneously offering tactics to ameliorate this risk (e.g. vaccination). Perceived concerns about vaccination can be tackled by reducing the omission bias (a perception that harm caused by action is worse than harm caused by inaction). In addition, interventions to increase seasonal influenza vaccination in advance of a future pandemic may be an effective strategy.     

Social and demographic patterns of influenza vaccination coverage in Norway,influenza seasons 2014/15 to 2020/21

AimsTo examine influenza vaccination coverage among risk groups (RG) and health care workers (HCW), and study social and demographic patterns of vaccination coverage over time.MethodsVaccination coverage was estimated by self-report in a nationally representative telephone survey among 14 919 individuals aged 18–79 years over seven influenza seasons from 2014/15 to 2020/21. We explored whether belonging to an influenza RG (being >=65 years of age and/or having >=1 medical risk factor), being a HCW or educational attainment was associated with vaccination status using logistic regression.ResultsVaccination coverage increased from 27 % to 66 % among individuals 65–79 years, from 13 % to 33 % among individuals 18–64 years with >=1 risk factor, and from 9 % to 51 % among HCWs during the study period. Being older, having a risk factor or being a HCW were significantly associated with higher coverage in all multivariable logistic regression analyses. Higher education was also consistently associated with higher coverage, but the difference did not reach significance in all influenza seasons. Educational attainment was not significantly associated with coverage while coverage was at its lowest (2014/15–2017/18), but as coverage increased, so did the differences. Individuals with intermediate or lower education were less likely to report vaccination than those with higher education in season 2018/19, OR = 0.61 (95 % CI 0.46–0.80) and OR = 0.58 (95 % CI 0.41–0.83), respectively, and in season 2019/20, OR = 0.69 (95 % CI 0.55–0.88) and OR = 0.71 (95 % CI 0.53–0.95), respectively. When the vaccine was funded in the COVID-19 pandemic winter of 2020/21, educational differences diminished again and were no longer significant.ConclusionsWe observed widening educational differences in influenza vaccination coverage as coverage increased from 2014/15 to 2019/20. When influenza vaccination was funded in 2020/21, differences in coverage by educational attainment diminished. These findings indicate that economic barriers influence influenza vaccination decisions among risk groups in Norway.     

Risk of Guillain-Barré syndrome after exposure to pandemic influenza A(H1N1)pdm09 vaccination or infection: a Norwegian population-based cohort study

Vaccinations and infections are possible triggers of Guillain-Barré syndrome (GBS). However, studies on GBS after vaccinations during the influenza A(H1N1)pmd09 pandemic in 2009, show inconsistent results. Only few studies have addressed the role of influenza infection. We used information from national health data-bases with information on the total Norwegian population (N = 4,832,211). Cox regression analyses with time-varying covariates and self-controlled case series was applied. The risk of being hospitalized with GBS during the pandemic period, within 42 days after an influenza diagnosis or pandemic vaccination was estimated. There were 490 GBS cases during 2009–2012 of which 410 cases occurred after October 1, 2009 of which 46 new cases occurred during the peak period of the influenza pandemic. An influenza diagnosis was registered for 2.47 % of the population and the vaccination coverage was 39.25 %. The incidence rate ratio of GBS during the pandemic peak relative to other periods was 1.46 [95 % confidence interval (CI) 1.08–1.98]. The adjusted hazard ratio (HR) of GBS within 42 days after a diagnosis of pandemic influenza was 4.89 (95 % CI 1.17–20.36). After pandemic vaccination the adjusted HR was 1.11 (95 % CI 0.51–2.43). Our results indicated that there was a significantly increased risk of GBS during the pandemic season and after pandemic influenza infection. However, vaccination did not increase the risk of GBS. The small number of GBS cases in this study warrants caution in the interpretation of the findings.     

Effectiveness of pandemic and seasonal influenza vaccines in preventing pandemic influenza-associated hospitalization

Vaccines are leading pharmacological measures for limiting the impact of pandemic influenza in the community. The objective of this study was to investigate the effectiveness of influenza (pandemic and seasonal) vaccines in preventing pandemic influenza-associated hospitalization. We conducted a multicenter matched case-control study in 36 Spanish hospitals. Patients hospitalized with confirmed pandemic influenza between November 2009 and February 2010 and two hospitalized controls per case, matched according to age, date of hospitalization and province of residence, were selected. Multivariate analysis was performed using conditional logistic regression. Subjects were considered vaccinated if they had received the vaccine >14 days (seasonal influenza vaccine) or >7 days (pandemic influenza vaccine) before the onset of symptoms (cases) or the onset of symptoms of the matched case (controls). For the pandemic influenza vaccine, vaccination effectiveness (VE) was estimated taking into account only patients recruited from November 23, 2009, seven days after the beginning of the pandemic influenza vaccination campaign. 638 cases and 1250 controls were included. The adjusted VE of the pandemic vaccine in the ≥18 years age group was 74.2% (95% CI, 29-90) and that of the influenza seasonal vaccine 15.0% (-34 to 43). The recommendation of influenza vaccination should be reinforced as a regular measure to reduce influenza-associated hospitalization during pandemics and seasonal epidemics.     

Long-lasting heterologous antibody responses after sequential vaccination with A/Indonesia/5/2005 and A/Vietnam/1203/2004 pre-pandemic influenza A(H5N1) virus vaccines

BackgroundAvian influenza A(H5N1) viruses have caused sporadic infections in humans and thus they pose a significant global health threat. Among symptomatic patients the case fatality rate has been ca. 50%. H5N1 viruses exist in multiple clades and subclades and several candidate vaccines have been developed to prevent A(H5N1) infection as a principal measure for preventing the disease.MethodsSerum antibodies against various influenza A(H5N1) clade viruses were measured in adults by ELISA-based microneutralization and haemagglutination inhibition tests before and after vaccination with two different A(H5N1) vaccines in 2009 and 2011.ResultsTwo doses of AS03-adjuvanted A/Indonesia/5/2005 vaccine induced good homologous but poor heterologous neutralizing antibody responses against different clade viruses. However, non-adjuvanted A/Vietnam/1203/2004 booster vaccination in 2011 induced very strong and long-lasting homologous and heterologous antibody responses while homologous response remained weak in naïve subjects.ConclusionsSequential vaccination with two different A(H5N1) pre-pandemic vaccines induced long-lasting high level cross-clade immunity against influenza A(H5N1) strains, thus supporting a prime-boost vaccination strategy in pandemic preparedness plans.     

Seasonal influenza vaccination predicts pandemic H1N1 vaccination uptake among healthcare workers in three countries

The aim of this study was to identify the common barriers and facilitators for acceptance of pandemic influenza vaccination across different countries. This study utilized a standardized, anonymous, self-completed questionnaire-based survey recording the demographics and professional practice, previous experience and perceived risk and severity of influenza, infection control practices, information of H1N1 vaccination, acceptance of the H1N1 vaccination and reasons of their choices and opinions on mandatory vaccination. Hospital-based doctors, nurses and allied healthcare workers in Hong Kong (HK), Singapore (SG) and Leicester, United Kingdom (UK) were recruited. A total of 6318 (HK: 5743, SG: 300, UK: 275) questionnaires were distributed, with response rates of 27.1% (HK), 94.7% (SG) and 94.5% (UK). The uptake rates for monovalent 2009 pandemic H1N1 vaccine were 13.5% (HK), 36.2% (SG) and 41.3% (UK). The single common factor associated with vaccine acceptance across all sites was having seasonal influenza vaccination in 2009. In UK and HK, overestimation of side effect reduced vaccination acceptance; and fear of side effect was a significant barrier in all sites. In HK, healthcare workers with more patient contact were more reluctant to accept vaccination. Drivers for vaccination in UK and HK were concern about catching the infection and following advice from health authority. Only a small proportion of respondents agreed with mandatory pandemic influenza vaccination (HK: 25% and UK: 42%), except in Singapore where 75.3% were in agreement. Few respondents (<5%) chose scientific publications as their primary source of information, but this group was more likely to receive vaccination.The acceptance of pandemic vaccine among healthcare workers was poor (13-41% of respondents). Breaking barriers to accept seasonal influenza vaccination should be part of the influenza pandemic preparedness plan. Mandatory vaccination even during pandemic is likely to arouse substantial discontent.     

Near real-time surveillance for Guillain-Barré syndrome after influenza vaccination among the Medicare population, 2010/11 to 2013/14

BackgroundGuillain-Barré syndrome (GBS) is a serious acute demyelinating disease that causes weakness and paralysis. The Food and Drug Administration (FDA) began collaborating with the Centers for Medicare and Medicaid Services (CMS) to develop near real-time vaccine safety surveillance capabilities in 2006 and has been monitoring for the risk of GBS after influenza vaccination for every influenza season since 2008.MethodsWe present results from the 2010/11 to 2013/14 influenza seasons using the Updating Sequential Probability Ratio Test (USPRT), with an overall 1-sided α of 0.05 apportioned equally using a constant alpha-spending plan among 20 consecutive weekly tests, 5 ad hoc tests, and a 26th final end of season test. Observed signals were investigated using the self-controlled risk interval (SCRI) design.ResultsOver 15 million people were vaccinated in each influenza season. In the 2010/11 influenza season, we observed an elevated GBS risk during the season, with an end of season SCRI analysis finding a nonsignificant increased risk (RR = 1.25, 95% CI: 0.96–1.63). A sensitivity analysis applying the positive predictive value of the ICD-9 code for GBS from the 2009/10 season estimated a RR = 1.98 (95% CI: 1.42–2.76). Although the 2010/11 influenza vaccine suggested an increased GBS risk, surveillance of the identical vaccine in the 2011/12 influenza season did not find an increased GBS risk after vaccination. No signal was observed in the subsequent three influenza seasons.ConclusionsConducting near real-time surveillance using USPRT has proven to be an excellent method for near real-time GBS surveillance after influenza vaccination, as demonstrated by our surveillance efforts during the 2010/11–2013/14 influenza seasons. In the 2010/2011 influenza season, in addition to the 2009 H1N1 influenza pandemic, using near real-time surveillance we were able to observe a signal early in the influenza season and the method has now become routine.     

Factors influencing pandemic influenza vaccination of healthcare workers--a systematic review

Introduction

Maintaining the health and availability of Health care workers (HCW) is an essential component of pandemic preparedness. A key to protecting HCW during the H1N1 pandemic was influenza vaccination. Numerous researchers have reported on factors influencing H1N1 vaccination behaviour in various HCW groups. This systematic review aims to inform future influenza vaccine interventions and pandemic planning processes via the examination of literature in HCW H1N1 vaccination, in order to identify factors that are (1) unique to pandemic influenza vaccination and (2) similar to seasonal influenza vaccination research.

Methods

We conducted a comprehensive review of literature (MEDLINE, PubMed, EMBASE, PsycINFO, CINHAL, AMED, Cochrane Library, ProQuest, and grey literature sources) published between January 2005 and December 2011 to identify studies relevant to HCW pH1N1 vaccine uptake/refusal.

Results

20 publications sampling HCW from different geographic regions are included in this review. H1N1 vaccine coverage was found to be variable (9–92%) across HCW populations, and self-reported vaccine status was the most frequently utilized predictor of pandemic vaccination. HCW were likely to accept the H1N1 vaccine if they perceived, (1) the H1N1 vaccine to be safe, (2) H1N1 vaccination to be effective in preventing infection to self and others (i.e. loved ones, co-workers and patients), and (3) H1N1 was a serious and severe infection. Positive cues to action, such as the access of scientific literature, trust in public health communications and messaging, and encouragement from loved ones, physicians and co-workers were also found to influence HCW H1N1 uptake. Previous seasonal influenza vaccination was found to be an important socio-demographic predictor of vaccine uptake. Factors unique to HCW pandemic vaccine behaviour are (1) lack of time and vaccine access related barriers to vaccination, (2) perceptions of novel and rapid pandemic vaccine formulation, and (3) the strong role of mass media on vaccine uptake.

Conclusions

Many of the factors that influenced HCW pandemic vaccination decisions have previously been reported in seasonal influenza vaccination literature, but some factors were unique to pandemic vaccination. Future influenza vaccine campaigns should emphasize the benefits of vaccination and highlight positive cues to vaccination, while addressing barriers to vaccine uptake in order to improve vaccine coverage among HCW populations. Since pandemic vaccination factors tend be similar among different HCW groups, successful pandemic vaccination strategies may be effective across numerous HCW populations in pandemic scenarios.     

No effect of 2008/09 seasonal influenza vaccination on the risk of pandemic H1N1 2009 influenza infection in England

This study reports effectiveness of trivalent influenza vaccine (TIV) against confirmed pandemic influenza infection in England using a retrospective test-negative case-control study. Cases and controls were frequency matched by age, swabbing-week and region. On univariable and multivariable analysis adjusted for underlying clinical risk factors, cases were no more or less likely than controls to be vaccinated with 2008-09 or 2007-08 season TIV. Adjusted vaccine effectiveness for the former was −6% (−43% to 22%). Vaccine effectiveness did not differ significantly by age-group or hospitalisation status. There was no evidence prior vaccination with TIV significantly altered subsequent risk of pandemic influenza H1N1 2009 infection.     

Vaccination against pandemic influenza A/H1N1 among healthcare workers and reasons for refusing vaccination in Istanbul in last pandemic alert phase

Coverage of the HCWs as target population is one of the important determinants for the impact of vaccination. To determine the vaccination against the pandemic influenza A/H1N1 among HCWs, we conducted a cross-sectional questionnaire survey in a public hospital in Istanbul from December 7 to December 22, 2009. Out of total 941 HCWs 718 (76.3%) completed the questionnaires. Nearly one-fourth (23.1%) of the participants were vaccinated against pandemic influenza A/H1N1. Occupation (being a doctor), receiving seasonal influenza vaccine in 2009, agreement with safety of pandemic influenza A/H1N1 vaccine and being comprehend that HCWs have a professional responsibility for getting vaccinated was the strongest independent predictive factor for accepting the pandemic influenza A/H1N1 vaccine (p < .0001). The most frequent reasons for refusing pandemic vaccine were fear of side effects and doubts about vaccine efficacy. Among HCWs 59.6% were recommending pandemic influenza vaccination to a patient even if indicated. In conclusion vaccination against pandemic influenza A/H1N1 is insufficient among HCWs. Misinformed or inadequately informed HCWs are important barrier to pandemic influenza vaccine coverage of the general public also. Educational campaigns concerning HCWs should include evidence based and comprehensible information about possible adverse effects and their incidence besides the advantages of vaccine.     

Declining influenza vaccination rates in an underserved pediatric primary care center during the COVID-19 pandemic

BackgroundInfluenza vaccination rates are decreasing in the United States. Disinformation surrounding COVID-related public health protections and SARS-CoV-2 vaccine roll-out may have unintended consequences impacting pediatric influenza vaccination. We assessed influenza vaccination rates before and during the COVID-19 pandemic in one pediatric primary care center, serving a minoritized population.MethodsA cross-sectional study assessed influenza vaccination rates for children aged 6 months to 12 years over the following influenza seasons (September-May): 1) 2018–19 and 2019–20 (pre-pandemic), and 2) 2020–21 and 2021–22 (intra-pandemic). Demographics and responses to social risk questionnaires were extracted from electronic health records. Total tetanus vaccinations across influenza seasons served as approximations of general vaccination rates. Generalized linear regression models with robust standard errors evaluated differences in demographics, social risks, and influenza vaccination rates by season. Multivariable logistic regression with robust standard errors evaluated associations between influenza season, demographics, social risks, and influenza vaccination.ResultsMost patients were young (mean age ～ 6 years), non-Hispanic Black (～80%), and publicly insured (～90%). Forty-two percent of patients eligible to receive the influenza vaccine who were seen in 2019–20 influenza season received the influenza vaccine, compared to 30% in 2021–22. Influenza and tetanus vaccination rates decreased during the COVID-19 pandemic (p < 0.01). The 2020–21 and 2021–22 influenza seasons, older age, Black race, and self-pay were associated with decreased influenza vaccine administration (p < 0.05).ConclusionsInfluenza vaccination rates within one pediatric primary care center decreased during the COVID-19 pandemic and have not rebounded, particularly for older children, those identifying as Black, and those without insurance.     

The determinants of 2009 pandemic A/H1N1 influenza vaccination: a systematic review

Background

Pandemic A/H1N1 influenza vaccine coverage varied widely across countries. To understand the factors influencing pandemic influenza vaccination and to guide the development of successful vaccination programs for future influenza pandemics, we identified and summarized studies examining the determinants of vaccination during the 2009 influenza pandemic.

Methods

We performed a systematic literature review using the PubMED electronic database from June 2009 to February 2011. We included studies examining an association between a possible predictive variable and actual receipt of the pandemic A/H1N1 influenza vaccine. We excluded studies examining intention or willingness to receive the vaccine.

Results

Twenty-seven studies were identified from twelve countries. Pandemic influenza vaccine coverage varied from 4.8% to 92%. Coverage varied by population sub-group, country, and assessment method used. Most studies used questionnaires to estimate vaccine coverage, however seven (26%) used a vaccination registry. Factors that positively influenced pandemic influenza vaccination were: male sex, younger age, higher education, being a doctor, being in a priority group for which vaccination was recommended, receiving a prior seasonal influenza vaccination, believing the vaccine to be safe and/or effective, and obtaining information from official medical sources.

Conclusions

Vaccine coverage during the pandemic varied widely across countries and population sub-groups. We identified some consistent determinants of this variation that can be targeted to increase vaccination during future influenza pandemics.