Cost-effectiveness of increased influenza vaccination uptake against readmissions of major adverse cardiac events in the US

Comparing the Clinical and Economic Outcomes Associated with Adjuvanted versus High-Dose Trivalent Influenza Vaccine among Adults Aged ≥ 65 Years in the US during the 2019-20 Influenza Season-A Retrospective Cohort Analysis

The burden of influenza is disproportionally higher among older adults. We evaluated the relative vaccine effectiveness (rVE) of adjuvanted trivalent (aIIV3) compared to high-dose trivalent influenza vaccine (HD-IIV3e) against influenza and cardio-respiratory disease (CRD)-related hospitalizations/ER visits among adults ≥65 years during the 2019-2020 influenza season. Economic outcomes were also compared. A retrospective cohort analysis was conducted using prescription, professional fee claims, and hospital data. Inverse probability of treatment weighting (IPTW) was used to adjust for confounding. IPTW-adjusted Poisson regression was used to evaluate the adjusted rVE of aIIV3 versus HD-IIV3e. All-cause and influenza-related healthcare resource utilization (HCRU) and costs were examined post-IPTW. Recycled predictions from generalized linear models were used to estimate adjusted costs. Adjusted analysis showed that aIIV3 (n = 798,987) was similarly effective compared to HD-IIV3e (n = 1,655,979) in preventing influenza-related hospitalizations/ER visits (rVE 3.1%; 95% CI: -2.8%; 8.6%), hospitalizations due to any cause (-0.7%; 95% CI: -1.6%; 0.3%), and any CRD-related hospitalization/ER visit (0.9%; 95% CI: 0.01%; 1.7%). Adjusted HCRU and annualized costs were also statistically insignificant between the two cohorts. The adjusted clinical and economic outcomes evaluated in this study were comparable between aIIV3 and HD-IIV3e during the 2019-2020 influenza season.

Influenza Vaccination for the Prevention of Cardiovascular Disease in the Americas: Consensus document of the Inter-American Society of Cardiology and the Word Heart Federation

Background

Cardiovascular mortality is decreasing but remains the leading cause of death world-wide. Respiratory infections such as influenza significantly contribute to morbidity and mortality in patients with cardiovascular disease. Despite of proven benefits, influenza vaccination is not fully implemented, especially in Latin America.

Objective

The aim was to develop a regional consensus with recommendations regarding influenza vaccination and cardiovascular disease.

Methods

A multidisciplinary team composed by experts in the management and prevention of cardiovascular disease from the Americas, convened by the Inter-American Society of Cardiology (IASC) and the World Heart Federation (WHF), participated in the process and the formulation of statements. The modified RAND/UCLA methodology was used. This document was supported by a grant from the WHF.

Results

An extensive literature search was divided into seven questions, and a total of 23 conclusions and 29 recommendations were achieved. There was no disagreement among experts in the conclusions or recommendations.

Conclusions

There is a strong correlation between influenza and cardiovascular events. Influenza vaccination is not only safe and a proven strategy to reduce cardiovascular events, but it is also cost saving. We found several barriers for its global implementation and potential strategies to overcome them.

Who receives influenza vaccinations at the Pharmacy? An analysis of the Texas Behavioral Risk Factor Surveillance System

INTRODUCTION

Vaccination helps to prevent influenza infection and reduce associated costs but the influenza vaccination rate in Texas for adults between the ages of 18 to 64 years old is the lowest in the US. Pharmacies and alternative locations have been shown to help increase vaccination rates but many adults still go unvaccinated.

OBJECTIVE

This research aims to determine the factors associated with obtaining influenza vaccination at the pharmacy compared to non-pharmacy locations in Texas.

METHOD

This study used pooled Texas Behavior Risk Factor Surveillance System datasets (2014 to 2018) for this assessment. The main outcome variable was categorized into pharmacy and non-pharmacy vaccination locations and analyzed using a logistic regression analysis. Further statistical analysis was done using a multinomial logistic regression after re-categorizing the outcome variable into pharmacy, doctor office, and other locations.

RESULT

Blacks were 63% (AOR 0.37, C.I. 0.26, 0.50) and Hispanics were 38% (AOR 0.62, C.I. 0.48, 0.80) less likely to receive influenza vaccinations at the pharmacy respectively when compared to Whites. Furthermore, those who did not live in a Metropolitan Statistical Area (MSA) were 33% (AOR 0.67, C.I 0.53, 0.84) less likely to receive influenza vaccinations at the pharmacy compared to those who lived in an MSA. While there was no observed difference in the likelihood of receiving influenza vaccination, the unemployed population were 40% (AOR 1.40, C.I 1.15, 1.71) more likely to be vaccinated in the pharmacy compared to the employed population.

CONCLUSION

There is potential for increased utilization of pharmacies as a source of influenza vaccination in Texas. Racial differences exist both for receiving influenza vaccinations and being vaccinated in the pharmacy. Influenza vaccination advocacy and education efforts may be necessary to improve pharmacy-based vaccination in Texas, especially for minorities and rural-dwelling Texans.

A retrospective cohort study assessing relative effectiveness of adjuvanted versus high-dose trivalent influenza vaccines among older adults in the United States during the 2018-19 influenza season

PURPOSE

To evaluate the relative vaccine effectiveness (rVE) against influenza-related hospitalizations/emergency room (ER) visits, influenza-related office visits, and cardio-respiratory disease (CRD)-related hospitalizations/ER visits and compare all-cause and influenza-related costs associated with two vaccines specifically indicated for older adults (≥65 years), adjuvanted (aTIV) and high-dose trivalent influenza vaccine (TIV-HD), for the 2018-19 influenza season.

METHODS

A retrospective analysis of older adults was conducted using claims and hospital data in the United States. For clinical evaluations, adjusted analyses were conducted following inverse probability of treatment weighting (IPTW) to control for selection bias. Poisson regression was used to estimate the adjusted rVE against influenza-related hospitalizations/ER visits, influenza-related office visits, and any CRD-related hospitalizations/ER visits. For the economic evaluation, treatment selection bias was adjusted through 1:1 propensity score matching (PSM). All-cause and influenza-related costs associated with hospitalizations/ER, physician office and pharmacy visits were adjusted using generalized estimating equation (GEE) models.

RESULTS

After IPTW and Poisson regression, aTIV (n = 561,315) was slightly more effective in reducing influenza-related office visits compared to TIV-HD (n = 1,672,779) (6.6%; 95% CI: 2.8-10.3%). aTIV was statistically comparable to TIV-HD (2.0%; 95% CI: -3.7%-7.3%) in preventing influenza-related hospitalizations/ER visits but more effective in reducing hospitalizations/ER visits for any CRD (2.6%; 95% CI: 2.0-3.2%). In the PSM-adjusted cohorts (n = 561,243 pairs), following GEE adjustments, predicted mean annualized all-cause and influenza-related total costs per patient were statistically similar between aTIV and TIV-HD (US$9676 vs. US$9625 and US$18.74 vs. US$17.28, respectively; both p > 0.05). Finally, influenza-related pharmacy costs were slightly lower for aTIV as compared to TIV-HD ($1.75 vs $1.85; p < 0.0001).

CONCLUSIONS

During the 2018-19 influenza season, influenza-related hospitalization/ER visits and associated costs among people aged ≥ 65 were comparable between aTIV and TIV-HD. aTIV was slightly more effective in preventing influenza-related office visits and any CRD event as compared to TIV-HD in this population.

Epidemiological Impact of SARS-CoV-2 Vaccination: Mathematical Modeling Analyses

This study aims to inform SARS-CoV-2 vaccine development/licensure/decision-making/implementation, using mathematical modeling, by determining key preferred vaccine product characteristics and associated population-level impacts of a vaccine eliciting long-term protection. A prophylactic vaccine with efficacy against acquisition (VE_S) ≥70% can eliminate the infection. A vaccine with VE_S <70% may still control the infection if it reduces infectiousness or infection duration among those vaccinated who acquire the infection, if it is supplemented with <20% reduction in contact rate, or if it is complemented with herd-immunity. At VE_S of 50%, the number of vaccinated persons needed to avert one infection is 2.4, and the number is 25.5 to avert one severe disease case, 33.2 to avert one critical disease case, and 65.1 to avert one death. The probability of a major outbreak is zero at VE_S ≥70% regardless of the number of virus introductions. However, an increase in social contact rate among those vaccinated (behavior compensation) can undermine vaccine impact. In addition to the reduction in infection acquisition, developers should assess the natural history and disease progression outcomes when evaluating vaccine impact.

Epidemiological Impact of SARS-CoV-2 Vaccination: Mathematical Modeling Analyses

This study aims to inform SARS-CoV-2 vaccine development/licensure/decision-making/implementation, using mathematical modeling, by determining key preferred vaccine product characteristics and associated population-level impacts of a vaccine eliciting long-term protection. A prophylactic vaccine with efficacy against acquisition (VES) ≥70% can eliminate the infection. A vaccine with VES <70% may still control the infection if it reduces infectiousness or infection duration among those vaccinated who acquire the infection, if it is supplemented with <20% reduction in contact rate, or if it is complemented with herd-immunity. At VES of 50%, the number of vaccinated persons needed to avert one infection is 2.4, and the number is 25.5 to avert one severe disease case, 33.2 to avert one critical disease case, and 65.1 to avert one death. The probability of a major outbreak is zero at VES ≥70% regardless of the number of virus introductions. However, an increase in social contact rate among those vaccinated (behavior compensation) can undermine vaccine impact. In addition to the reduction in infection acquisition, developers should assess the natural history and disease progression outcomes when evaluating vaccine impact.

Evaluating the Relative Vaccine Effectiveness of Adjuvanted Trivalent Influenza Vaccine Compared to High-Dose Trivalent and Other Egg-Based Influenza Vaccines among Older Adults in the US during the 2017-2018 Influenza Season

The influenza-related disease burden is highest among the elderly. We evaluated the relative vaccine effectiveness (rVE) of adjuvanted trivalent influenza vaccine (aTIV) compared to other egg-based influenza vaccines (high-dose trivalent (TIV-HD), quadrivalent (QIVe-SD), and standard-dose trivalent (TIVe-SD)) against influenza-related and cardio-respiratory events among subjects aged ≥65 years for the 2017–2018 influenza season. This retrospective cohort analysis used prescription claims, professional fee claims, and hospital charge master data. Influenza-related hospitalizations/ER visits and office visits and cardio-respiratory events were assessed post-vaccination. Inverse probability of treatment weighting (IPTW) and Poisson regression were used to evaluate the adjusted rVE of aTIV compared to other vaccines. In an economic analysis, annualized follow-up costs were compared between aTIV and TIV-HD. The study was composed of 234,313 aTIV, 1,269,855 TIV-HD, 212,287 QIVe-SD, and 106,491 TIVe-SD recipients. aTIV was more effective in reducing influenza-related office visits and other respiratory-related hospitalizations/ER visits compared to the other vaccines. For influenza-related hospitalizations/ER visits, aTIV was associated with a significantly higher rVE compared to QIVe-SD and TIVe-SD and was comparable to TIV-HD. aTIV was also associated with a significantly higher rVE compared to TIVe-SD against hospitalizations/ER visits related to pneumonia and asthma/COPD/bronchial events. aTIV and TIV-HD were associated with comparable annualized all-cause and influenza-related costs. Adjusted analyses demonstrated a significant benefit of aTIV against influenza- and respiratory-related events compared to the other egg-based vaccines.

Vaccine effectiveness against influenza A(H3N2) and B among laboratory-confirmed, hospitalised older adults, Europe, 2017-18: A season of B lineage mismatched to the trivalent vaccine

Background

Influenza A(H3N2), A(H1N1)pdm09 and B viruses co‐circulated in Europe in 2017‐18, predominated by influenza B. WHO‐recommended, trivalent vaccine components were lineage‐mismatched for B. The I‐MOVE hospital network measured 2017‐18 seasonal influenza vaccine effectiveness (IVE) against influenza A(H3N2) and B among hospitalised patients (≥65 years) in Europe.

Methods

Following the same generic protocol for test‐negative design, hospital teams in nine countries swabbed patients ≥65 years with recent onset (≤7 days) severe acute respiratory infection (SARI), collecting information on demographics, vaccination status and underlying conditions. Cases were RT‐PCR positive for influenza A(H3N2) or B; controls: negative for any influenza. “Vaccinated” patients had SARI onset >14 days after vaccination. We measured pooled IVE against influenza, adjusted for study site, age, sex, onset date and chronic conditions.

Results

We included 3483 patients: 376 influenza A(H3N2) and 928 B cases, and 2028 controls. Most (>99%) vaccinated patients received the B lineage‐mismatched trivalent vaccine. IVE against influenza A(H3N2) was 24% (95% CI: 2 to 40); 35% (95% CI: 6 to 55) in 65‐ to 79‐year‐olds and 14% (95% CI: −22 to 39) in ≥80‐year‐olds. Against influenza B, IVE was 30% (95% CI: 16 to 41); 37% (95% CI: 19 to 51) in 65‐ to 79‐year‐olds and 19% (95% CI: −7 to 38) in ≥80‐year‐olds.

Conclusions

IVE against influenza B was similar to A(H3N2) in hospitalised older adults, despite trivalent vaccine and circulating B lineage mismatch, suggesting some cross‐protection. IVE was lower in those ≥80 than 65‐79 years. We reinforce the importance of influenza vaccination in older adults as, even with a poorly matched vaccine, it still protects one in three to four of this population from severe influenza.