Led by Anna Catriona Phillips of the University of Birmingham, researchers assessed the response to a hepatitis A vaccine in young healthy adults and also examined responses to the annual influenza vaccination in older community-based adults.

In the first study, participants consisted of 75 University of Birmingham students who were vaccinated with the hepatitis A vaccine during a morning session (10 am to 12 pm) or early evening session (4 pm to 6 pm). In the second study, 90 older adults attended their medical practice for the annual influenza vaccination and received the vaccination in the morning between 8 am and 11 am or in the afternoon between 1 pm and 4 pm.

Men vaccinated in the morning showed the strongest immune response. Almost twice as many men showed a twofold increase in antibody response when vaccinated in the morning as opposed to the afternoon.

“If we can replicate these findings in a randomized controlled trial, there would be implications for the time of day for vaccinating those at risk,” the authors conclude. “Adults could be vaccinated at a specific time of day to increase their protection against the flu.”

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Journal Reference:

1. Phillips et al. Preliminary evidence that morning vaccination is associated with an enhanced antibody response in men. Psychophysiology, 2008; 45 (4): 663 DOI: 10.1111/j.1469-8986.2008.00662.x