Mike Coston is the Owner/Editor of Avian Flu Diary

The effectiveness of the flu jab can vary widely from one person to the next, and over the years we’ve seen a number of theories as to why this might be. The usual suspects – age (over 65), or a less than robust immune system – are often cited as likely factors, but other theories include:


Overnight a new study, published overnight in the Journal Vaccine, has been making headlines with a new possibility: that the time of day you are vaccinated may make a difference in your body’s immune response.

The cluster-randomized trial followed 276 adults (over 65) across 24 GP practices in the West Midlands, UK who – between 2011 and 2013 – were assigned to receive their flu shots either in the morning or afternoon.

Follow up blood work showed substantially higher antibodies against H1N1 and Influenza B (but not H3N2) in the morning vaccination cohort.

The poor performance of H3N2 vaccines over the past few years may have contributed to the less than stellar improvement for that strain (seeBranswell: H3N2 Remains the `Weak Link’ In The Flu Vaccine). 

While the results suggest morning vaccination may increase vaccine effectiveness, this study (like all studies) is subject to some limitations, and confirmatory studies are needed. Follow the link below to read it in its entirety.

Joanna E. Longa, Mark T. Draysonb,Angela E. Taylord, Kai M. Toellnerb, Janet M. Lordc, 1, Anna C. Phillipsa, 1, ,

doi:10.1016/j.vaccine.2016.04.032Get rights and content

Open Access funded by Medical Research Council

Under a Creative Commons license


• Early small studies provide mixed evidence for effects of time of vaccination on antibody response.
• This is the first large scale randomised trial of different times of vaccination.
•  Morning vaccination enhances the antibody response to the influenza vaccine.
•  This simple manipulation is cost neutral and may improve protection from influenza in older adults.

   ABSTRACT (Excerpts)


We utilised a cluster-randomised trial design.


24 General Practices (GPs) across the West Midlands, UK who were assigned to morning (9–11 am; 15 surgeries) or afternoon (3–5 pm; 9 surgeries) vaccination times for the annual UK influenza vaccination programme.


276 adults (aged 65+ years and without a current infection or immune disorder or taking immunosuppressant medication).

Participants were vaccinated in the morning or afternoon between 2011 and 2013.

Main outcome measures

The primary outcome was the change in antibody titres to the three vaccine influenza strains from pre-vaccination to one month post-vaccination. Secondary outcomes of serum cytokines and steroid hormone concentrations were analysed at baseline to identify relationships with antibody responses.


The increase in antibody levels due to vaccination differed between morning and afternoon administration; mean difference (95% CI) for H1N1 A-strain, 293.3 (30.97–555.66) p = .03, B-strain, 15.89 (3.42–28.36) p = .01, but not H3N2 A-strain, 47.0 (−52.43 to 146.46) p = .35; those vaccinated in the morning had a greater antibody response. Cytokines and steroid hormones were not related to antibody responses. No adverse events were reported.

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From the University of Birmingham press release:

Vaccinations are more effective when administered in the morning 

New research from the University of Birmingham has shown that flu vaccinations are more effective when administered in the morning.

The findings, published in the journal Vaccine, suggest administering vaccinations in the morning, rather than the afternoon, could induce greater, and thus more protective, antibody responses.


Dr Anna Phillips, the Principal Investigator of the study from the School of Sport, Exercise and Rehabilitation Sciences at the University of Birmingham explained, “We know that there are fluctuations in immune responses throughout the day and wanted to examine whether this would extend to the antibody response to vaccination. Being able to see that morning vaccinations yield a more efficient response will not only help in strategies for flu vaccination, but might provide clues to improve vaccination strategies more generally.”

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