Research results have shown that the high-dose influenza vaccine (flu vaccine) is safe even in groups at high risk of cardiovascular disease.
High-dose influenza vaccine was associated with higher response rates, including greater increases in antibody titers, but was not associated with an increased risk of cardiorespiratory hospitalization or all-cause death.
The results of a study on the immune response of high-dose influenza vaccination in groups at high risk of cardiovascular disease conducted by Alexander Paykert and others at the Brigham and Women’s Hospital in the United States were published on the 7th in the international journal JAMA Network ( doi :10.1001/jamacardio.2024.0468).
Usually, the flu vaccine takes two weeks to a month to develop immunity, but it does not provide complete protection from the virus.
One study showed that even if a high-dose group of cardiovascular patients received a high-dose flu vaccine, there was no significant difference in mortality compared to the standard-dose group.
The vaccine prevention rate in healthy adults reaches 70-90%, and in the elderly, influenza-related complications can be reduced by 50-60% through vaccination.
The effectiveness of vaccination varies depending on age or health status and is particularly less effective in the elderly or chronically ill people with low antibody production capacity.
High-dose flu vaccines that have increased vaccine prevention rates by increasing antigen content have been marketed at home and abroad, but some fear that broader antibody responses at high doses could lead to negative responses in groups at high risk of cardiovascular diseases.
To confirm this, researchers conducted the INVESTED clinical trial to compare the rate of antibody seroconversion and mortality rate between the standard-dose quadrivalent influenza vaccine and the high-dose trivalent influenza vaccine in patients recently hospitalized for myocardial infarction or heart failure.
The clinical trial was designed to compare high-dose trivalents and standard-dose quadrivalents in a double-blind manner at 157 medical institutions in the United States and Canada over the course of three influenza seasons from September 2016 to January 2019.
Antibody titers were collected during the 2017-2018 and 2018-2019 seasons, and eligible patients were limited to those with a recent acute myocardial infarction or hospitalization for heart failure and one or more additional cardiovascular risk factors.
Actionable antibody data was collected from 658 of 5260 participants.
The analysis found that the high-dose vaccine was associated with increased antibody titers against the A/H1N1, A/H3N2 and B antigens compared to standard doses, with more than 92% of participants achieving seroprotection against each antigen , but antibody seroconversion rates were lower at high doses and was higher in the vaccinated group.
It was observed that the risk of cardiopulmonary hospitalization or all-cause mortality did not increase even with increasing seroconversion rate (hazard ratio 1.09).
The researchers said: “Results from the INVESTED clinical trial showed that the high-dose vaccine had a stronger seroconversion rate in groups at high risk of cardiovascular disease such as heart failure. However, there was no correlation with the risk of cardiovascular disease hospitalization or death from any cause.” It has been presented as a useful flu prevention strategy.
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