Infectious Disease

The effectiveness of the flu vaccine decreases by about 10% per 30 days after the shot

February 09, 2021

2 min read

Source / information

Published by:

Disclosure:
Ferdinands does not report any relevant financial information. In the study you will find all relevant financial information from all other authors.

ADD SUBJECT TO EMAIL ALARMS

Receive an email when new articles are published

Please enter your email address to receive an email when new articles are published . “data-action =” subscribe “> subscribe

We could not process your request. Please try again later. If you continue to have this problem, please contact customerservice@slackinc.com.

Back to Healio

The immunity provided by influenza vaccines decreases by about 10% after vaccination every month after vaccination. This emerges from the study results published in Clinical Infectious Diseases. Researchers said September or October would be the best months to get the shot.

“In the US, an annual influenza vaccine is recommended for anyone 6 months or older. However, the best time to get an annual flu vaccine is still up for debate. ” Jill M. Ferdinands, PhD, an epidemiologist in the CDC’s influenza division, said Healio. “With evidence growing that vaccine-induced immunity wanes over the course of the flu season, it is important to consider whether vaccinating early – in July or August, for example – before the end of the season could result in decreased immune protection against flu in March and May , especially in older adults. “

Flu shot

The researchers observed a “significant” decrease in immunity to influenza vaccines between 8% and 9% per month after vaccination.
Photo credit: Adobe Stock

According to Ferdinands, the current recommendations seek to offset the need to immunize the population before the flu starts circulating each year and fear immunity wears off by recommending vaccination be offered by the end of October.

“This study hoped to better understand the extent to which influenza vaccine protection declines during the season in order to reduce uncertainty about when to get a flu shot,” she said.

Ferdinands and colleagues evaluated the vaccine’s effectiveness in adults enrolled in the U.S. Influenza Vaccine Network (HAIVEN) who were hospitalized for acute respiratory disease from 2015-2016 through 2018-2019. According to the study, participants were interviewed to gather information about demographics, vaccination, and disease characteristics while breath samples were tested for influenza. Patients who tested positive for influenza were treated as cases and those who tested negative were counted as controls. The researchers then used multivariate logistic regression models with influenza-associated hospitalization as a result and the time in days between vaccination and onset of symptoms as a predictor for assessing the effectiveness of the vaccine.

Overall, the study showed that the effectiveness of the influenza vaccine peaks shortly after vaccination and then at the rate of 8% per 30 days against Influenza A (H3N2), 9% per 30 days against Influenza A (H1N1) and 8 % per 30 days decreases against influenza B virus in all adults aged 18 and over.

Ferdinands found that in adults aged 65 and over, the declines are even greater, with efficacy against influenza A (H3N2) decreasing by 11% per 30 days, against influenza A (H1N1) by 10% per 30 days and 11% against Influenza B viruses.

“The study found that the immunity to flu provided by vaccines declines significantly during the season. The public health implications of these results need further investigation, as optimizing the timing of influenza vaccination could result in significant gains in public health benefits given the large burden of influenza morbidity and mortality in the US, ” said Ferdinands.

“Getting vaccinated in July or August is likely too early, especially for adults 65 and over, as the likelihood of less protection from flu infections later in the flu season is less,” she said. “Right now, September and October are good times for most people to get vaccinated.”

ADD SUBJECT TO EMAIL ALARMS

Receive an email when new articles are published

Please enter your email address to receive an email when new articles are published . “data-action =” subscribe “> subscribe

We could not process your request. Please try again later. If you continue to have this problem, please contact customerservice@slackinc.com.

Back to Healio

Related Articles