High dose flu shot no better than standard one in high risk CVD patients: JAMA
Researchers have observed in a new study that in patients with high-risk cardiovascular disease, high-dose trivalent influenza vaccine, compared with the standard-dose quadrivalent vaccine, did not significantly reduce all-cause mortality or hospitalizations for cardiac or pulmonary causes.High-dose influenza vaccine is not superior to standard-dose vaccine in high-risk adults with cardiovascular disease (CVD).
This study is published in the JAMA Network.
Influenza is temporally associated with cardiopulmonary morbidity and mortality among those with cardiovascular disease who may mount a less vigorous immune response to vaccination. Higher influenza vaccine dose has been associated with reduced risk of influenza illness.
The Centers for Disease Control and Prevention recommends annual influenza vaccination in those 6 months or older and professional cardiovascular societies emphasize annual influenza vaccination in patients with cardiovascular conditions, without specific guidance regarding the choice of vaccine formulation.
Hence, Orly Vardeny and associates from the Department of Medicine, University of Minnesota, Minneapolis VA Health Care System, Minneapolis, Minnesota conducted this study to evaluate whether high-dose trivalent influenza vaccine compared with standard-dose quadrivalent influenza vaccine would reduce all-cause death or cardiopulmonary hospitalization in high-risk patients with cardiovascular disease.
A total of 5260 participants were randomly assigned to receive high-dose trivalent (n = 2630) or standard-dose quadrivalent (n = 2630) inactivated influenza vaccine and could be revaccinated for up to 3 seasons. The primary outcome was the time to the composite of all-cause death or cardiopulmonary hospitalization during each enrolling season.
Among the participants, 7154 total vaccinations were administered and 5226 (99.4%) participants completed the trial. In the high-dose trivalent vaccine group, there were 975 primary outcome events (883 hospitalizations for cardiovascular or pulmonary causes and 92 deaths from any cause) among 884 participants during 3577 participant-seasons (event rate, 45 per 100 patient-years), whereas in the standard-dose quadrivalent vaccine group, there were 924 primary outcome events (846 hospitalizations for cardiovascular or pulmonary causes and 78 deaths from any cause) among 837 participants during 3577 participant-seasons.
The authors noted that in the high-dose vs standard-dose groups, vaccine-related adverse reactions occurred in 1449 (40.5%) vs 1229 (34.4%) participants and severe adverse reactions occurred in 55 (2.1%) vs 44 (1.7%) participants.
Therefore, they concluded that "in patients with high-risk cardiovascular disease, high-dose trivalent inactivated influenza vaccine, compared with standard-dose quadrivalent inactivated influenza vaccine did not significantly reduce all-cause mortality or cardiopulmonary hospitalizations. Influenza vaccination remains strongly recommended in this population."
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JAMA. Published online December 4, 2020. doi:10.1001/jama.2020.23649
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