Vaccine

Influenza vaccine

Also known as: Seasonal flu shot

Best time

Morning appointment

09:00–11:00

Morning flu shots produced higher antibody levels than afternoon shots in older adults.

Emerging evidence

Promising early or observational research — not yet standard practice everywhere.

Why this time works

A UK randomised trial in adults over 65 found vaccination between 09:00 and 11:00 gave larger antibody responses to some flu strains than 15:00–17:00. Immune cell activity and hormone levels such as cortisol and melatonin vary across the day.

Body rhythm involved

Immune cell trafficking and responsiveness follow a daily rhythm.