Receipt Of Seasonal Influenza Vaccine Research Articles

A single blinded, phase IV, adaptive randomised control trial to evaluate the safety of coadministration of seasonal influenza and COVID-19 vaccines (The FluVID study)

ObjectivesWe evaluated the frequency of moderate and severe adverse events following coadministration of seasonal influenza vaccine (SIV) versus placebo with COVID-19 vaccines among adults to support practice guidelines. MethodsFluVID is a participant-blinded, phase IV, randomised control trial. On the same day as the participant’s scheduled COVID-19 vaccine, participants were randomised to receive SIV or saline placebo; those assigned placebo at visit one then received SIV a week later, and vice versa. Self-reported adverse events were collected daily for seven days following each visit.The primary endpoint was any solicited adverse event of at least moderate severity occurring up to seven days following receipt of SIV or placebo. This was modelled using a Bayesian logistic regression model. Analyses were performed by COVID-19 vaccine type and dose number. ResultsOverall, 248 participants were enrolled; of these, 195 had received BNT162b2 and 53 had received mRNA1273 COVID-19 vaccines according to national guidelines. After randomisation, 119 were assigned to receive SIV and 129 were assigned to receive placebo at visit one.Adverse events were most frequently reported as mild (grade 1) in nature. Among 142 BNT162b2 booster dose one and 43 BNT162b2 booster dose two recipients, the posterior median risk difference for moderate/severe adverse events following SIV versus placebo was 13% (95% credible interval [CrI] −0.03 to 0.27) and 13% (95%CrI −0.37 to 0.12), respectively. Among 18 mRNA1273 booster dose one and 35 mRNA1273 booster dose two recipients, the posterior median risk difference of moderate/severe adverse events following influenza vaccine versus placebo was 6% (95%CrI −0.29 to 0.41) and −4% (95%CrI −0.30 to 0.23), respectively. ConclusionAdverse events following SIV and COVID-19 co-administration were generally mild and occurred with similar frequency to events following COVID-19 vaccine alone. We found no evidence to justify routine separation of SIV and COVID-19 vaccine doses.Clinical trial registration: ACTRN12621001063808.

Care-seeking correlates of acute respiratory illness among sheltered adults experiencing homelessness in Seattle, WA, 2019: a community-based cross-sectional study.

Multifarious barriers to accessing healthcare services among people experiencing homelessness (PEH) lead to delays in seeking care for acute infections, including those caused by respiratory viruses. PEH are at high risk of acute respiratory illness (ARI)-related complications, especially in shelter settings that may facilitate virus spread, yet data characterizing healthcare utilization for ARI episodes among sheltered PEH remained limited. We conducted a cross-sectional study of viral respiratory infection among adult residents at two homeless shelters in Seattle, Washington between January and May 2019. We assessed factors associated with seeking medical care for ARI via self-report. We collected illness questionnaires and nasal swabs were tested for respiratory viruses by reverse transcription quantitative real-time PCR (RT-qPCR). We observed 825 encounters from 649 unique participants; 241 (29.2%) encounters reported seeking healthcare for their ARI episode. Seasonal influenza vaccine receipt (adjusted prevalence ratio [aPR] 1.39, 95% CI 1.02-1.88), having health insurance (aPR 2.77, 95% CI 1.27-6.02), chronic lung conditions (aPR 1.55, 95% CI 1.12-2.15), and experiencing influenza-like-illness symptoms (aPR 1.63, 95% CI 1.20 - 2.20) were associated with increased likelihood of seeking care. Smoking (aPR 0.65, 95% CI 0.45-0.92) was associated with decreased likelihood of seeking care. Findings suggest that care seeking for viral respiratory illness among PEH may be supported by prior engagement with primary healthcare services. Strategies to increase healthcare utilization may lead to earlier detection of respiratory viruses.

Receipt of COVID-19 and seasonal influenza vaccines in California (USA) during the 2021-2022 influenza season.

Despite lower circulation of influenza virus throughout 2020-2022 during the COVID-19 pandemic, seasonal influenza vaccination has remained a primary tool to reduce influenza-associated illness and death. The relationship between the decision to receive a COVID-19 vaccine and/or an influenza vaccine is not well understood. We assessed predictors of receipt of 2021-2022 influenza vaccine in a secondary analysis of data from a case-control study enrolling individuals who received SARS-CoV-2 testing. We used mixed effects logistic regression to estimate factors associated with receipt of seasonal influenza vaccine. We also constructed multinomial adjusted marginal probability models of being vaccinated for COVID-19 only, seasonal influenza only, or both as compared with receipt of neither vaccination. Among 1261 eligible participants recruited between 22 October 2021-22 June 2022, 43% (545) were vaccinated with both seasonal influenza vaccine and >1 dose of a COVID-19 vaccine, 34% (426) received >1 dose of a COVID-19 vaccine only, 4% (49) received seasonal influenza vaccine only, and 19% (241) received neither vaccine. Receipt of >1 COVID-19 vaccine dose was associated with seasonal influenza vaccination (adjusted odds ratio [aOR]: 3.72; 95% confidence interval [CI]: 2.15-6.43); this association was stronger among participants receiving >1 COVID-19 booster dose (aOR = 16.50 [10.10-26.97]). Compared with participants testing negative for SARS- CoV-2 infection, participants testing positive had lower odds of receipt of 2021-2022 seasonal influenza vaccine (aOR = 0.64 [0.50-0.82]). Recipients of a COVID-19 vaccine were more likely to receive seasonal influenza vaccine during the 2021-2022 season. Factors associated with individuals' likelihood of receiving COVID-19 and seasonal influenza vaccines will be important to account for in future studies of vaccine effectiveness against both conditions. Participants who tested positive for SARS-CoV-2 in our sample were less likely to have received seasonal influenza vaccine, suggesting an opportunity to offer influenza vaccination before or after a COVID-19 diagnosis.

Delays and declines in seasonal influenza vaccinations due to Hurricane Harvey narrow annual gaps in vaccination by race, income and rurality.

Temporal overlap of the Atlantic hurricane season and seasonal influenza vaccine rollout has the potential to result in delays or disruptions of vaccination campaigns. We documented seasonal influenza vaccination behavior over a 5-year period and explored associations between flooding following Hurricane Harvey and timing and uptake of vaccines, as well as how the impacts of Hurricane Harvey on vaccination vary by race, wealth, and rurality. Retrospective cohort analysis. Texas counties affected by Hurricane Harvey. Active users of the Veterans' Health Administration in 2017. We used geocoded residential address data to assess flood exposure status following Hurricane Harvey. Days to receipt of seasonal influenza vaccines were calculated for each year from 2014 to 2019. Proportional hazards models were used to determine how likelihood of vaccination varied according to flood status as well as the race, wealth, and rural-urban residence of patients. The year of Hurricane Harvey was associated with a median delay of 2 weeks to vaccination and lower overall vaccination than in prior years. Residential status in flooded areas was associated with lower hazards of influenza vaccination in all years. White patients had higher proportional hazards of influenza vaccination than non-White patients, though this attenuated to 6.39% (hazard ratio [HR], 1.0639; 95% confidence interval [CI], 1.034-1.095) in the hurricane. year. Receipt of seasonal influenza vaccination following regional exposure to the effects of Hurricane Harvey was delayed among US veterans. White, non-low-income, and rural patients had higher likelihood of vaccination in all years of the study, but these gaps narrowed during the hurricane year.

Identification of groups at high risk for under-coverage of seasonal influenza vaccination: A national study to inform vaccination priorities during the COVID-19 pandemic

PurposeSeasonal influenza vaccination is an important public health strategy to reduce preventable illness, hospitalization, and death. Because of overlapping risk factors for severe illness from seasonal influenza and COVID-19, uptake of the seasonal influenza vaccination has heightened importance during the COVID-19 pandemic. We analyzed receipt of seasonal influenza vaccination among COVID-19 priority groups and further examined socio-demographic and behavioral factors associated with receiving the seasonal influenza vaccine among US adults. MethodsUsing the 2018 National Health Interview Survey, we classified 24,772 adults into four COVID-19 priority groups: healthcare workers, medically vulnerable, non-healthcare essential workers, and the general population. We performed multiple logistic regression to compare the relative odds of receiving the influenza vaccine by COVID-19 priority group, socio-demographics, and health-related factors. ResultsHealthcare workers, medically vulnerable adults, essential workers, and the general population comprised 8.9%, 58.4%, 6.6%, and 26.1 % of the US population, respectively. Compared with healthcare workers, the adjusted odds ratio (aOR) of receiving influenza vaccine were significantly lower in medically vulnerable adults (aOR=0.43, 95% CI=0.37, 0.48), essential workers (aOR=0.28, 95% CI=0.23, 0.34), and the general population (aOR=0.32, 95% CI=0.28, 0.37). Being young, male, Black, and having no health insurance were associated with lower relative odds of receiving the flu vaccine. ConclusionsPatterns of influenza vaccine cause concern for under-coverage of populations at high risk for both seasonal influenza and COVID-19. Achieving optimal protection against vaccine-preventable respiratory illness in US adults will require emphasis on those employed outside of the healthcare sector, younger age groups, and adults with lower socioeconomic resources.

1238Estimating the non-specific effects of seasonal influenza vaccine on RSV-hospitalisations in children

Abstract Background Seasonal influenza vaccine is effective against influenza hospitalisations, but little is known about non-specific effects on other respiratory pathogens with similar seasonal patterns. We aimed to assess the causal impact of seasonal influenza vaccine on laboratory-confirmed hospitalisations for respiratory syncytial virus (RSV) in children using an instrumental variable (IV) strategy. Methods We used population-based probabilistically linked data on births, childhood immunisations, deaths, hospitalisations, perinatal and statewide microbiology data (2000-2013) in Western Australia (WA). Our analysis cohort included children up to age 7 years. We exploited WA’s unique preschool influenza vaccination policy commencing in 2008 and used this as an instrument for vaccination status. We estimated a system of two simultaneous probit equations: determinants of influenza vaccine uptake, and determinants of RSV-confirmed hospitalisation. Results Influenza vaccine coverage was low prior to 2008 but increased to 33.7% in children aged 6-23 months in 2009. RSV-hospitalisations ranged from 3.5/1000 children (12-23 months) to 6.4/1000 (6-12 months). Receipt of seasonal influenza vaccine reduced RSV-hospitalisations in the population cohort of children aged <2 years by an average of 0.21% in the same year (p < 0.001). Conclusions To our knowledge, this is the first analysis utilising an IV estimation strategy to assess the impact of influenza vaccine on RSV-hospitalisations. We estimated a small, but highly statistically significant impact that warrants further investigation using contemporary data. Key messages RSV is a leading cause of childhood morbidity. The role of influenza vaccine offering cross protection to RSV could be further explored prior to RSV vaccines being commercially available.

Effect of race and ethnicity on influenza vaccine uptake among older US Medicare beneficiaries: a record-linkage cohort study

Seasonal influenza vaccine (SIV) uptake among US adults aged 65 years or older remains suboptimal and stagnant. Further, there is growing concern around racial and ethnic disparities in uptake. We aimed to assess racial and ethnic disparities in overall SIV and in high-dose vaccine (HDV) uptake among Medicare beneficiaries during the 2015-16 influenza season and sought to identify possible mediators for observed disparities. We did a historical record-linkage cohort study using Medicare (a US national health insurance programme) databases, which included all older adults (≥65 years) enrolled in Medicare during the study period (July 1, 2015, to June 30, 2016). We excluded beneficiaries of Medicare Part C (managed care offered by private companies), and residents of long-term care facilities. The primary outcome was SIV receipt during the study period, classified into receipt of HDV and standard-dose vaccines (SDVs, representing all other SIVs). SIV uptake probabilities were estimated using competing-risk survival analysis methods. Mediation analyses were done to investigate potential mediators of the association between race and ethnicity and uptake. During the study period, of 26·5 million beneficiaries in the study cohort, 47·4% received a SIV, 52·7% of whom received HDV. Compared with white beneficiaries (49·4%), Hispanic (29·1%), Black (32·6%), and Asian (47·6%) beneficiaries were less likely to be vaccinated and, when vaccinated, were less likely to receive HDV (37·8% for Hispanic people, 41·1% for Black people, and 40·3% for Asian people, compared with 53·8% of white people who received HDV). Among those vaccinated, after accounting for region, income, chronic conditions, and health-care use, minority groups were 26-32% less likely to receive HDV, relative to white people (odds ratio [OR] 0·68 [95% CI 0·68-0·69] for Black people; OR 0·71 [0·71-0·72] for Asian people; and OR 0·74 [0·73-0·74] for Hispanic people). Substantial racial and ethnic disparities in SIV uptake among Medicare beneficiaries aged 65 years or older are evident. New legislative, fiscal, and educational strategies are urgently needed to address these inequities. Sanofi Pasteur.

Immunogenicity and safety of different dose schedules and antigen doses of an MF59-adjuvanted H7N9 vaccine in healthy adults aged 65 years and older

BackgroundThe number of human influenza A (H7N9) infections has escalated since 2013 with high resultant mortality. We conducted a phase II, randomized, partially-blinded trial to evaluate the safety and immunogenicity of an MF59-adjuvanted inactivated, split virion, H7N9 influenza vaccine (H7N9 IIV) administered at various dose levels and schedules in older adults. Methods479 adults ≥ 65 years of age in stable health were randomized to one of six groups to receive either 3.75, 7.5 or 15 µg of influenza A/Shanghai/02/2013 (H7N9) IIV adjuvanted with MF59 given as a 3-dose series either on days 1, 28 and 168 or on days 1, 57 and 168. Immunogenicity was assessed using both hemagglutination inhibition (HAI) and microneutralization (MN) assays prior to and 28 days following each dose. Safety was assessed through 1 year following the last dose. ResultsSubjects in all groups had only modest immune responses, with the HAI GMT < 20 after the second vaccine dose and <29 after the third vaccine dose. HAI titers ≥ 40 were seen in <37% of subjects after the second dose and <49% after the third dose. There were no significant differences seen between the two dose schedules. MN titers followed similar patterns, although the titers were approximately two-fold higher than the HAI titers. Logistic regression modeling demonstrated no statistically significant associations between the immune responses and age, sex or body mass index whereas recent prior receipt of seasonal influenza vaccine significantly reduced the HAI response [OR 0.13 (95% CI 0.05, 0.33); p < 0.001]. Overall, the vaccine was well tolerated. Two mild potentially immune mediated adverse events occurred, lichen planus and guttate psoriasis. ConclusionsMF59-adjuvanted H7N9 IIV was only modestly immunogenic in the older adult population following three doses. There were no significant differences in antibody responses noted among the various antigen doses or the two dose schedules.

Influenza Vaccination Coverage and (SARS-CoV-2) Seroprevalance in a Fire Department

Purpose: The confluence of seasonal influenza and COVID-19 disease during Fall 2020 will give rise to considerable morbidity and mortality, likely stressing the U.S. healthcare system. Firefighter/paramedic first responders are at risk of being exposed to pathogens such as coronavirus and the avian flu, that can be transmitted between the patients they serve. We estimate influenza vaccination rates by coronavirus infection status in one large metropolitan Florida career fire department. Methods: We used a cross-sectional study design to estimate flu vaccination prevalence among all frontline firefighter/paramedic workers from a fire department participating in a seroprevalence study. Participants initially provided consent and completed a 76-item web-based survey. Seasonal influenza vaccination was assessed in the 12-months prior to coronavirus testing. Off- and on-duty firefighters/paramedics were subsequently tested for SARS-CoV-2 antibodies using a rapid immunoglobulin (Ig)M-IgG combined lateral flow immunoassay during April/May 2020. Results: Among the 1,555 participating firefighters/paramedics, 8.5% reported receipt of the seasonal flu vaccine, and 4.1% tested SARS-CoV-2 antibody positive. None of the antibody-positive firefighters/paramedics reported receipt of the seasonal influenza vaccine compared to those who tested negative (0.0% vs. 8.5%;p=0.012). After controlling for potential confounders, firefighters/paramedics who were Hispanic/Latino vs non-Hispanic/Latino (Adjusted Odds Ratio, AOR, 0.33 [95% confidence interval=0.20–0.55]), former smokers vs never smokers (AOR:0.47 [0.24-0.93]), and had one or more chronic conditions vs no chronic diseases(AOR:0.33 [0.15-0.75]) were significantly less likely to report seasonal influenza vaccine receipt. Conclusion: Influenza vaccination rates were very low among frontline firefighters/paramedics in a large Florida fire department. Acknowledgements: Research reported in this publication was supported in part by a grant award from the Florida Blue Foundation (PI Caban-Martinez) and by the National Cancer Institute of the National Institutes of Health under Award Number P30CA240139. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Florida Blue Foundation, Blue Cross and Blue Shield of Florida nor the National Institutes of Health.

Investigating the association of receipt of seasonal influenza vaccine with occurrence of anesthesia/paresthesia and severe headaches, Canada 2012/13–2016/17, the Canadian Vaccine Safety Network

BackgroundConcern about adverse events following immunization is frequently cited by both those who receive or decline vaccines. Neurological adverse events are especially concerning. ObjectivesOur aim was to detect associations between seasonal influenza vaccination and the occurrence of severe anesthesia/paresthesia or severe headaches. MethodsData were analyzed from the Canadian National Vaccine Safety network. Events occuring on days 0–7 were self-reported and prevented daily activity, led to school or work absenteeism, or required medical attention. Controls were the previous year’s vaccinees; events in controls were collected prior to the start of the influenza vaccination program of each year (2012/13 through 2016/17). Multivariable logistic regression was used to determine the association between seasonal influenza vaccination and the occurrence of anesthesia/paresthesia or severe headaches. ResultsThe total sample was 107,565 for investigating anesthesia/paresthesia and 97,420 for investigating severe headaches. Anesthesia/paresthesia was reported by 104/107,565 (0.10%) participants; 63/69,129 (0.09%) vaccinees and 41/38,436 (0.11%) controls (adjusted odds ratio (aOR) = 0.89; 95% CI = 0.60, 1.32). Severe headaches were reported by 1361/97,420 (1.40%) participants; 907/61,463 (1.48%) vaccinees and 454/35,957 (1.26%) controls (aOR = 1.21; 95% CI = 1.08, 1.36). No specific vaccine product was associated with severe headaches. ConclusionsOur study found no association between severe anesthesia/paresthesia and seasonal influenza vaccination. While there was an association with severe headaches as an adverse event following influenza vaccination, the rates of these events are similar to rates reported from clinical trials and are not a cause for additional concern.

Influenza Vaccine Effectiveness in Preventing Hospitalizations in Older Patients With Chronic Obstructive Pulmonary Disease.

Annual influenza immunization is recommended for people with chronic obstructive pulmonary disease (COPD) by all major COPD clinical practice guidelines. We sought to determine the seasonal influenza vaccine effectiveness (VE) against laboratory-confirmed influenza-associated hospitalizations among older adults with COPD. We conducted a test-negative study of influenza VE in community-dwelling older adults with COPD in Ontario, Canada using health administrative data and respiratory specimens collected from patients tested for influenza during the 2010-11 to 2015-16 influenza seasons. Influenza vaccination was ascertained from physician and pharmacist billing claims. Multivariable logistic regression was used to estimate the adjusted odds ratio of influenza vaccination in people with, compared to those without, laboratory-confirmed influenza. Receipt of seasonal influenza vaccine was associated with an adjusted 22% (95% confidence interval [CI], 15%-27%) reduction in laboratory-confirmed influenza-associated hospitalization. Adjustment for potential misclassification of vaccination status increased this to 43% (95% CI, 35%-52%). Vaccine effectiveness was not found to vary by patient- or influenza-related variables. During the studied influenza seasons, influenza vaccination was at least modestly effective in reducing laboratory-confirmed influenza-associated hospitalizations in people with COPD. The imperfect effectiveness emphasizes the need for better influenza vaccines and other preventive strategies.

Vaccine-associated reduction in symptom severity among patients with influenza A/H3N2 disease

BackgroundThe moderate level of protection conferred by influenza vaccines is well-known, but the vaccine's ability to attenuate symptom severity among vaccinated individuals (i.e., vaccine failures) has not been established. MethodsWe enrolled otherwise healthy adults who presented with influenza-like illness (ILI) at five US military hospitals between 2009 and 2014. Influenza was diagnosed and subtyped by PCR. Individual and composite severity scores were compared between those who had vs. had not received the seasonal influenza vaccine >14 days prior to enrollment. ResultsA total of 155 cases of influenza (A/H1N1, n=69; A/H3N2, n=66; A/untyped, n=3; B, n=17) were identified, of whom 111 (72%; A/H1N1, n=44; A/H3N2, n=52; A/untyped, n=3; B, n=12) had been vaccinated. Women were significantly less likely to be vaccinated than men (49% vs. 89%; p<0.01). In multivariate analysis, vaccinated individuals were significantly less likely to report a fever >101°F (OR 0.24; 95% CI [0.10, 0.62]) and more likely to report myalgias (OR 3.31; 95% CI [1.22, 8.97]) than vaccinated individuals. Among patients with A/H3N2 infection, upper respiratory and total symptom severity scores were significantly lower for vaccinated patients during the first 2 days of illness, and differences in total symptom severity persisted over 7 days (p<0.05 for all comparisons). Differences across additional symptom categories (lower respiratory and systemic) were also observed throughout 7 days of illness in bivariate analyses. Differences in symptom severity were not observed between vaccinated and unvaccinated participants with A/H1N1 infection. ConclusionsAmong patients with A/H3N2 infection, receipt of seasonal influenza vaccine was associated with reduced symptom severity. Patient-centered discussion about the benefits of influenza vaccination should be expanded to include the possibility that the vaccine could attenuate symptoms.

Serological evidence of equine influenza infections among persons with horse exposure, Iowa

BackgroundEquine influenza virus (EIV) is considered enzootic in North America and experimental studies have documented human EIV infections. Study designThis cross-sectional study examined 94 horse-exposed and 34 non-exposed controls for serological evidence of EIV infection. Sera were evaluated for antibodies against three EIV and two human H3N2 viruses using microneutralization (MN), neuraminidase inhibition (NI), enzyme-linked lectin (ELLA), and hemagglutination inhibition (HI) serological assays. Risk factor analyses were conducted using logistic regression and proportional odds modeling. ResultsThere was evidence of previous infection by MN assay against A/equine/Ohio/2003(H3N8) but not the other 2 EIVs. Eleven (11.7%, maximum titer 1:320) horse-exposed and 2 (5.9%, maximum titer 1:160) control subjects had MN titers ≥1:80. Among the horse-exposed, 18 (19.1%) were positive by NI assay and 8 (8.5%) had elevated ELLA titers ≥1:10. Logistic regression modeling among horse-exposed revealed that having an elevated MN or ELLA titer (≤1:10) was associated with having a positive NI titer (OR=4.9; 95% CI=1.3–18.7, and OR=53.2; 95% CI=5.9–478.5, respectively). Upon proportional odds modeling, having worked as an equine veterinarian (OR=14.0; 95% CI=2.6–75.9), having a history of smoking (OR=3.1; 95% CI=1.2–7.7), and receipt of seasonal influenza vaccine between 2000 and 2005 (OR=2.3; 95% CI=1.1–5.0) were important independent risk factors for elevations in MN assay. ConclusionsWhile we cannot rule out confounding exposures, these data support the premise that occupational exposure to EIV may lead to human infection.

Seasonal influenza vaccination is the strongest correlate of cross-reactive antibody responses in migratory bird handlers.

ABSTRACTAvian species are reservoirs of influenza A viruses and could harbor viruses with significant pandemic potential. We examined the antibody and cellular immune responses to influenza A viruses in field or laboratory workers with a spectrum of occupational exposure to avian species for evidence of zoonotic infections. We measured the seroprevalence and T cell responses among 95 individuals with various types and degrees of prior field or laboratory occupational exposure to wild North American avian species using whole blood samples collected in 2010. Plasma samples were tested using endpoint enzyme-linked immunosorbent assay (ELISA) and hemagglutination (HA) inhibition (HAI) assays to subtypes H3, H4, H5, H6, H7, H8, and H12 proteins. Detectable antibodies were found against influenza HA antigens in 77% of individuals, while 65% of individuals tested had measurable T cell responses (gamma interferon [IFN-γ] enzyme-linked immunosorbent spot assay [ELISPOT]) to multiple HA antigens of avian origin. To begin defining the observed antibody specificities, Spearman rank correlation analysis showed that ELISA responses, which measure both head- and stalk-binding antibodies, do not predict HAI reactivities, which measure primarily head-binding antibodies. This result suggests that ELISA titers can report cross-reactivity based on the levels of non-head-binding responses. However, the strongest positive correlate of HA-specific ELISA antibody titers was receipt of seasonal influenza virus vaccination. Occupational exposure was largely uncorrelated with serological measures, with the exception of individuals exposed to poultry, who had higher levels of H7-specific antibodies than non-poultry-exposed individuals. While the cohort had antibody and T cell reactivity to a broad range of influenza viruses, only occupational exposure to poultry was associated with a significant difference in antibody levels to a specific subtype (H7). There was no evidence that T cell assays provided greater specificity for the detection of zoonotic infection. However, influenza vaccination appears to promote cross-reactive antibodies and may provide enhanced protection to novel influenza viruses.

Factors associated with influenza vaccine receipt in community dwelling adults and their children

BackgroundFactors associated with influenza vaccine receipt are well studied in healthcare personnel, pregnant women, and the elderly. There has been substantially less research in community dwelling adults and children, and none among entire households. Many studies determine vaccination status by self-report or behavioral intention, outcomes susceptible to misclassification. Given that vaccine is recommended for everyone over six months, re-evaluating these factors is warranted. MethodsThe Household Influenza Vaccine Effectiveness (HIVE) study is a prospective cohort of households with children. In 2010–2011, 549 adults representing 312 households completed surveys evaluating knowledge, attitudes, and practices regarding influenza vaccination for themselves and their children. Using the health belief model (HBM) as a framework, we examined factors associated with documented seasonal influenza vaccine receipt using log-binomial regression models. ResultsIn multivariate models, cues to action such as doctor recommendation, (RR 1.62, 95% CI: 1.25–2.10), perceived benefits (RR 1.25, 95% CI: 1.04–1.50), and perceived susceptibility (RR 1.21, 95% CI: 1.03–1.42) were significantly associated with increased likelihood of vaccine receipt among adults while high perceived barriers were associated with decreased likelihood (RR 0.38, 95% CI: 0.25–0.59). Similarly, parents reporting higher barriers were less likely (RR 0.58, 95% CI: 0.42–0.79) and those perceiving greater benefits (RR 4.16, 95% CI: 2.28–7.59) and severity (RR 1.13, 95% CI: 1.00–1.27 were more likely to vaccinate their children. The observed effects of perceptions of susceptibility, severity, and benefits were more pronounced at low cues to action for children, as were the effects of perceptions of barriers and severity among adults. ConclusionPerceived benefits and barriers are most strongly associated with vaccine receipt. However, the effects of various factors were most pronounced in the absence of cues to action, which may be an important component of targeted interventions.

Seasonal Influenza Vaccination at School

Influenza vaccination coverage for U.S. school-aged children is below the 80% national goal. Primary care practices may not have the capacity to vaccinate all children during influenza vaccination season. No real-world models of school-located seasonal influenza (SLV-I) programs have been tested. Determine the feasibility, sustainability, and impact of an SLV-I program providing influenza vaccination to elementary school children during the school day. In this pragmatic randomized controlled trial of SLV-I during two vaccination seasons, schools were randomly assigned to SLV-I versus standard of care. Seasonal influenza vaccine receipt, as recorded in the state immunization information system (IIS), was measured. Intervention and control schools were located in a single western New York county. Participation (intervention or control) included the sole urban school district and suburban districts (five in Year 1, four in Year 2). After gathering parental consent and insurance information, live attenuated and inactivated seasonal influenza vaccines were offered in elementary schools during the school day. Data on receipt of ≥1 seasonal influenza vaccination in Year 1 (2009-2010) and Year 2 (2010-2011) were collected on all student grades K through 5 at intervention and control schools from the IIS in the Spring of 2010 and 2011, respectively. Additionally, coverage achieved through SLV-I was compared to coverage of children vaccinated elsewhere. Preliminary data analysis for Year 1 occurred in Spring 2010; final quantitative analysis for both years was completed in late Fall 2012. Results are shown for 2009-2010 and 2010-2011, respectively: Children enrolled in suburban SLV-I versus control schools had vaccination coverage of 47% vs 36%, and 52% vs 36% (p<0.0001 both years). In urban areas, coverage was 36% vs 26%, and 31% vs 25% (p<0.001 both years). On multilevel logistic analysis with three nested levels (student, school, school district) during both vaccination seasons, children were more likely to be vaccinated in SLV-I versus control schools; ORs were 1.6 (95% CI=1.4, 1.9; p<0.001) and 1.5 (95% CI=1.3, 1.8; p<0.001). Delivering influenza vaccine during school is a promising approach to improving pediatric influenza vaccination coverage. ClinicalTrials.govNCT01224301.

Pandemic influenza A(H1N1)pdm09: risk of infection in primary healthcare workers

Healthcare workers in primary care are at risk of infection during an influenza pandemic. The 2009 influenza pandemic provided an opportunity to assess this risk. To measure the prevalence of seropositivity to influenza A(H1N1)pdm09 among primary healthcare workers in Canterbury, New Zealand, following the 2009 influenza pandemic, and to examine associations between seropositivity and participants' sociodemographic characteristics, professional roles, work patterns, and seasonal influenza vaccination status. An observational study involving a questionnaire and testing for influenza A(H1N1)pdm09 seropositivity in all primary healthcare workers in Canterbury, New Zealand between December 2009 and February 2010. Method Participants completed a questionnaire that recorded sociodemographic and professional data, symptoms of influenza-like illness, history of seasonal influenza vaccination, and work patterns. Serum samples were collected and haemagglutination inhibition antibody titres to influenza A(H1N1)pdm09 measured. Questionnaires and serum samples were received from 1027 participants, from a workforce of 1476 (response rate 70%). Seropositivity was detected in 224 participants (22%). Receipt of seasonal influenza vaccine (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.2 to 3.3), recall of influenza (OR = 1.9, 95% CI = 1.3 to 2.8), and age ≤45 years (OR = 1.4, 95% CI = 1.0 to 1.9) were associated with seropositivity. A total of 22% of primary care healthcare workers were seropositive. Younger participants, those who recalled having influenza, and those who had been vaccinated against seasonal influenza were more likely to be seropositive. Working in a dedicated influenza centre was not associated with an increased risk of seropositivity.

Examination of pneumococcal vaccination rates among U.S. adult smokers

Pneumococcal vaccination rates among U.S. adult smokers in rural and nonrural areas were compared to determine the effect of federal vaccination recommendations. Using bivariate and multivariate techniques, 2005 and 2010 Behavioral Risk Factor Surveillance Survey data were analyzed for comparative purposes. The dependent variable for this analysis was receipt of pneumococcal vaccine. The population of interest was U.S. adults age 19-64 years who reported that they currently smoked. Covariates included sex, race and ethnicity, household income, educational attainment, geographic area (rural or nonrural location of last routine medical checkup), having a personal health care provider, having health insurance, deferring medical care because of cost, self-defined health status, and receipt of seasonal influenza vaccination in the past 12 months. Results In 2005, 15.5% of smokers reported that they had ever received a pneumonia vaccine; by 2010, this percentage increased to 20.8%. In 2005, rural adult smokers were more likely to receive a pneumococcal vaccine (odds ratio [OR], 1.357; 95% confidence interval [CI], 1.338-1.377) than their nonrural counterparts. In 2010, rural adult smokers were less likely to receive the vaccine (OR, 0.952; 95% CI, 0.938-0.966). In both years, men were more likely to receive pneumococcal vaccine, as were those with health insurance and a health care provider. Overall, receipt of a seasonal influenza vaccine was the strongest predictor of smokers receiving pneumococcal vaccine. U.S. adult smokers were most likely to receive pneumococcal vaccine if they were men, had health insurance, had a health care provider, and received a seasonal influenza vaccination within the past year.

The potential effect of temporary immunity as a result of bias associated with healthy users and social determinants on observations of influenza vaccine effectiveness; could unmeasured confounding explain observed links between seasonal influenza vaccine and pandemic H1N1 infection?

BackgroundFive observational studies from Canada found an association between seasonal influenza vaccine receipt and increased risk of pandemic influenza H1N1 2009 infection. This association remains unexplained. Although uncontrolled confounding has been suggested as a possible explanation, the nature of such confounding has not been identified. Observational studies of influenza vaccination can be affected by confounding due to healthy users and the influence of social determinants on health. The purpose of this study was to investigate the influence that these two potential confounders may have in combination with temporary immunity, using stratified tables. The hypothesis is that respiratory virus infections may activate a temporary immunity that provides short-term non-specific protection against influenza and that the relationship with being a healthy user or having a social determinant may result in confounding.MethodsWe simulated the effect of confounding on vaccine effectiveness assuming that this could result from both social determinants and healthy user effects as they both influence the risk of seasonal influenza and non-influenza respiratory virus infections as well as the likelihood of being vaccinated. We then examined what impact this may have had on measurement of seasonal influenza vaccine effectiveness against pandemic influenza.ResultsIn this simulation, failure to adjust for healthy users and social determinants would result in an erroneously increased risk of pandemic influenza infection associated with seasonal influenza vaccination. The effect sizes were not however large.ConclusionsWe found that unmeasured healthy user effects and social determinants could result in an apparent association between seasonal influenza vaccine and pandemic influenza infection by virtue of being related to temporary immunity. Adjustment for social determinants of health and the healthy user effects are required in order to improve the quality of observational studies of influenza vaccine effectiveness.

Who got vaccinated against H1N1 pandemic influenza? – A longitudinal study in four US cities

The recent H1N1 pandemic influenza stimulated numerous studies into the attitudes and intentions about the H1N1 vaccine. However, no study has investigated prospective predictors of vaccination behaviour. We conducted a two-wave longitudinal study among residents in four US cities during the course of the H1N1 outbreak, using Internet surveys to assess demographic, cognitive and emotional predictors of H1N1 vaccination behaviour. Surveys were conducted at two time points, before (Time 1) and after (Time 2) the H1N1 vaccine was widely available to the public. Results show that Time 2 vaccination rates, but not Time 1 vaccination intentions, tracked H1N1 prevalence across the four cities. Receipt of seasonal influenza vaccine in the previous year, worry, compliance with recommended interventions, household size and education assessed at Time 1 were significant prospective predictors of vaccination behaviour. Perception of the H1N1 vaccine, social influence and prioritised vaccine recipient status assessed at Time 2 also predicted vaccination behaviour. Critically, worry about H1N1 mediated the effects of both objective risk (prevalence at the city level) and perceived risk on vaccination behaviour. These results suggest that H1N1 vaccination behaviour appropriately reflected objective risk across regions, and worry acted as the mechanism by which vaccination behaviour followed objective risk.