Influenza vaccination and risk for cardiovascular events: a nationwide self-controlled case series study

Risk of stroke within 3, 7, 14, 21 and 30 days after influenza vaccination in Alberta, Canada: A population-based study

BACKGROUND AND PURPOSE

Influenza vaccination is associated with a longer-term protective effect against stroke; however, it has a short-term inflammatory response which may increase short-term risk of stroke. The aim was to investigate the association between influenza vaccination and short-term risk of stroke in adults.

METHODS

Administrative data were obtained from the Alberta Health Care Insurance Plan for all adults in Alberta, Canada, from September 2009 to December 2018. The hazard of any stroke (acute ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage and transient ischaemic attack) within 3, 7, 14, 21 and 30 days of influenza vaccination compared to unexposed time was analysed using Andersen-Gill Cox models, with adjustment for age, sex, anticoagulant use, atrial fibrillation, chronic obstructive pulmonary disease, diabetes, hypertension, income quintile, and rural or urban home location.

RESULTS

In the entire cohort consisting of 4,141,209 adults (29,687,899 person-years), 1,769,565 (42.7%) individuals received at least one vaccination. In total 38,126 stroke events were recorded with 1309 occurring within 30 days of a vaccination event. Influenza vaccination was associated with a significantly reduced hazard of stroke within 3 days (hazard ratio [HR] 0.83, 95% confidence interval [CI] 0.73-0.93), 7 days (HR 0.87, 95% CI 0.80-0.95), 14 days (HR 0.87, 95% CI 0.81-0.93), 21 days (HR 0.85, 95% CI 0.80-0.91) and 30 days (HR 0.66, 95% CI 0.65-0.68).

CONCLUSIONS

An increased early risk associated with vaccination was not observed. The risk of stroke was reduced at all time points within 30 days after influenza vaccination.

Effectiveness of Vaccines and Monoclonal Antibodies Against Respiratory Syncytial Virus: Generic Protocol for Register-Based Cohort Study

Several immunization products are currently being developed against respiratory syncytial virus (RSV) for children, pregnant females, and older adults, and some products have already received authorization. Therefore, studies to monitor the effectiveness of these products are needed in the following years. To assist researchers to conduct postmarketing studies, we developed a generic protocol for register-based cohort studies to evaluate immunization product effectiveness against RSV-specific and nonspecific outcomes. To conduct a study on the basis of this generic protocol, the researchers can use any relevant databases or healthcare registers that are available at the study site.

Influenza vaccination in mitigating vascular events and risk

PURPOSE OF REVIEW

Influenza imparts a significant health burden on the United States and global population. Furthermore, influenza is associated with acute cardiovascular events, including heart failure exacerbations, acute coronary syndromes, strokes, and overall cardiovascular mortality. We review the role of seasonal influenza vaccination in mitigating cardiovascular risk.

RECENT FINDINGS

A large study assessed the impact of influenza vaccine on cardiovascular outcomes and mortality using the US National Inpatient Sample (NIS) database. This study included 22 634 643 hospitalizations. Vaccination against influenza was associated with a reduction in myocardial infarctions (MI) [relative risk (RR) = 0.84, 95% CI 0.82-0.87, P  < 0.001], transient ischemic attacks (RR = 0.93, 95% CI 0.9-0.96, P  < 0.001), cardiac arrests (RR = 0.36, 95% CI 0.33-0.39, P  < 0.001), strokes (RR = 0.94, 95% CI 0.91-0.97, P  < 0.001), and overall mortality (RR = 0.38, 95% CI 0.36-0.4, P  < 0.001).

SUMMARY

Available data suggests that seasonal influenza vaccination is very effective in mitigating cardiovascular risk. Increasing the rates of influenza vaccination, especially among those with cardiovascular risk factors, is critical in preventing infection and attenuating influenza-related cardiovascular complications and adverse outcomes.

Analysis of hematologic adverse events reported to a national surveillance system following COVID-19 bivalent booster vaccination

Hematologic complications, including vaccine-induced immune thrombotic thrombocytopenia (VITT), immune thrombocytopenia (ITP), and autoimmune hemolytic anemia (AIHA), have been associated with the original severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. However, on August 31, 2022, new formulations of the Pfizer-BioNTech and Moderna vaccines were approved for use without clinical trial testing. Thus, any potential adverse hematologic effects with these new vaccines remain unknown. We queried the US Centers for Disease Control Vaccine Adverse Event Reporting System (VAERS), a national surveillance database, through February 3, 2023, all reported hematologic adverse events that occurred within 42 days of administration of either the Pfizer-BioNTech or Moderna Bivalent COVID-19 Booster vaccine. We included all patient ages and geographic locations and utilized 71 unique VAERS diagnostic codes pertaining to a hematologic condition as defined in the VAERS database. Fifty-five reports of hematologic events were identified (60.0% Pfizer-BioNTech, 27.3% Moderna, 7.3% Pfizer-BioNTech bivalent booster plus influenza, 5.5% Moderna bivalent booster plus influenza). The median age of patients was 66 years, and 90.9% (50/55) of reports involved a description of cytopenias or thrombosis. Notably, 3 potential cases of ITP and 1 case of VITT were identified. In one of the first safety analyses of the new SARS-CoV-2 booster vaccines, we identified few adverse hematologic events (1.05 per 1,000,000 doses), most of which could not be definitively attributed to vaccination. However, three reports of possible ITP and one report of possible VITT highlight the need for continued safety monitoring of these vaccines as their use expands and new formulations are authorized.

Primary prevention of acute cardiovascular events by influenza vaccination: an observational study

AIMS

Previous studies show a reduced incidence of first myocardial infarction and stroke 1-3 months after influenza vaccination, but it is unclear how underlying cardiovascular risk impacts the association.

METHODS AND RESULTS

The study used linked Clinical Practice Research Datalink, Hospital Episode Statistics Admitted Patient Care and Office for National Statistics mortality data from England between 1 September 2008 and 31 August 2019. From the data, individuals aged 40-84 years with a first acute cardiovascular event and influenza vaccination occurring within 12 months of each September were selected. Using a self-controlled case series analysis, season-adjusted cardiovascular risk stratified incidence ratios (IRs) for cardiovascular events after vaccination compared with baseline time before and >120 days after vaccination were generated. 193 900 individuals with a first acute cardiovascular event and influenza vaccine were included. 105 539 had hypertension and 172 050 had a QRISK2 score ≥10%. In main analysis, acute cardiovascular event risk was reduced in the 15-28 days after vaccination [IR 0.72 (95% CI 0.70-0.74)] and, while the effect size tapered, remained reduced to 91-120 days after vaccination [0.83 (0.81-0.88)]. Reduced cardiovascular events were seen after vaccination among individuals of all age groups and with raised and low cardiovascular risk.

CONCLUSIONS

Influenza vaccine may offer cardiovascular benefit among individuals at varying cardiovascular risk. Further studies are needed to characterize the populations who could derive the most cardiovascular benefits from vaccination.

Influenza vaccine and risk of acute myocardial infarction in a population-based case-control study

OBJECTIVE

To assess the relationship between influenza vaccination and risk of a first acute myocardial infarction (AMI) in the general population by different epidemic periods.

METHODS

This is a population-based case-control study carried out in BIFAP (Base de datos para la investigación farmacoepidemiológica en atención primaria), over 2001-2015, in patients aged 40-99 years. Per each incident AMI case, five controls were randomly selected, individually matched for exact age, sex and index date (AMI diagnosis). A patient was considered vaccinated when he/she had a recorded influenza vaccination at least 14 days before the index date within the same season. The association between influenza vaccination and AMI risk was assessed through a conditional logistic regression, computing adjusted ORs (AOR) and their respective 95% CIs. The analysis was performed overall and by each of the three time epidemic periods per study year (pre-epidemic, epidemic and postepidemic).

RESULTS

We identified 24 155 AMI cases and 120 775 matched controls. Of them, 31.4% and 31.2%, respectively, were vaccinated, yielding an AOR of 0.85 (95% CI 0.82 to 0.88). No effect modification by sex, age and background cardiovascular risk was observed. The reduced risk of AMI was observed shortly after vaccination and persisted over time. Similar results were obtained during the pre-epidemic (AOR=0.87; 95% CI 0.79 to 0.95), epidemic (AOR=0.89; 95% CI 0.82 to 0.96) and postepidemic (AOR=0.83; 95% CI 0.79 to 0.87) periods. No association was found with pneumococcal vaccine (AOR=1.10; 95% CI 1.06 to 1.15).

CONCLUSIONS

Results are compatible with a moderate protective effect of influenza vaccine on AMI in the general population, mostly in primary prevention, although bias due to unmeasured confounders may partly account for the results.

Associations between Combined Influenza and Pneumococcal Pneumonia Vaccination and Cardiovascular Outcomes

BACKGROUND

In 2017, the CDC listed heart disease as the leading cause of death, with pneumonia and influenza being the eighth cause of death. Several studies have suggested the protective effects of influenza vaccination on myocardial infarction (MI). Available evidence supports the use of influenza vaccination in decreasing cardiovascular events, and the Joint Commission considers influenza vaccination a metric of quality care for hospitalized patients. Our specific aim was to evaluate the combined use of pneumococcal pneumonia vaccine (PPV) and influenza vaccine on cardiovascular outcomes and mortality.

METHODS

A retrospective observational study was conducted using the 2012-2015 US National Inpatient Sample (NIS) database, to compare cardiovascular events in adult patients who did and did not receive vaccination during their hospitalization. ICD-9 codes were used to extract data for specific variables. The outcomes included MI, transient ischemic attacks, cardiac arrest, stroke, heart failure, and death. Adjusted relative risks (RR) were calculated using survey-weighted generalized linear models after adjusting for gender, race, socioeconomic status, diabetes, hypertension, hyperlipidemia, smoking status, prior coronary artery disease, and cerebrovascular disease. The effect of vaccination on in-hospital mortality was assessed in each subgroup of cardiovascular events using RR regressions.

RESULTS

This study included 22,634,643 hospitalizations, of which 21,929,592 did not receive immunization. Vaccination solely against influenza was associated with lower MI (RR = 0.84, 95% CI: 0.82-0.87, p < 0.001), TIA (RR = 0.93, 95% CI: 0.9-0.96, p < 0.001), cardiac arrest (RR = 0.36, 95% CI: 0.33-0.39, p < 0.001), stroke (RR = 0.94, 95% CI: 0.91-0.97, p < 0.001), and mortality (RR = 0.38, 95% CI: 0.36-0.4, p < 0.001). Vaccination with PPV alone was associated with MI (RR = 1.13, 95% CI: 1.11-1.16, p < 0.001), TIA (RR = 1.28, 95% CI: 1.26-1.31, p < 0.001), stroke (RR = 1.21, 95% CI: 1.18-1.24, p < 0.001), and lower mortality (RR = 0.47, 95% CI: 0.45-0.49, p < 0.001). Combined PPV and influenza vaccine was associated with lower mortality (2.21% vs. 1.03%, p < 0.001) and lower cardiac arrest (0.61% vs. 0.51%, p < 0.001). In the adjusted analysis, the RR was 0.46 (95% CI: 0.43, 0.49) for mortality in the combined vaccinated cohort. The combined vaccination group also had a significantly reduced risk of mortality among those admitted with MI (RR = 0.46), transient ischemic attacks (RR = 0.58), and stroke (RR = 0.42) compared to the nonvaccinated group.

CONCLUSIONS

Our study shows a significantly reduced risk of mortality with influenza vaccine and PPV and with combined pneumococcal and influenza vaccination. These data suggest that in-hospital administration of pneumonia and influenza vaccines appears safe and supports the use of combined vaccination during hospitalization due to their cardiovascular benefits.

[Vaccination against community acquired pneumonia in adults. Update 2021 of the position paper by Neumoexpertos en Prevención Group]

Community-acquired pneumonia (CAP) continues to be an important cause of morbidity and mortality in adults. The aim of this study is to update the practical prevention guide for CAP through vaccination in Spain developed in 2016 and updated in 2018, based on available vaccines and evidence through bibliographic review and expert opinion. The arrival of COVID-19 as a new cause of CAP and the recent availability of safe and effective vaccines constitutes the most significant change. Vaccines against pneumococcus, influenza, pertussis and COVID-19 can help to reduce the burden of disease from CAP and its associated complications. The available evidence supports the priority indications established in this guide, and it would be advisable to try to achieve a widespread dissemination and implementation of these recommendations in routine clinical practice.