Vaccinations in the morning may result in a more enhanced antibody response in older adults, a new study published in Vaccine has found.

Immune aging contributes to older adults being less able to produce protective antibody responses to vaccinations. Study authors from the University of Birmingham, United Kingdom (UK) set out to examine whether diurnal variations in immune responses would apply to the antibody response to vaccination by conducting a non-blinded, cluster-randomized trial.

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The data showed that the rise in antibody levels due to vaccination were different between the morning and afternoon administration groups with a mean difference of 293.3 (95% CI: 30.97-555.66; P=0.03) for H1N1 A-strain and 15.89 (95% CI: 3.42–28.36; P=0.01) for H1N1 B-strain, demonstrating that those vaccinated in the morning exhibited a greater antibody response. Antibody levels did not differ between the morning and afternoon groups for the H3N2 A-strain (treatment difference 47.0, 95% CI: -52.43–146.46; P=0.35).

Study authors also reported no relationship between antibody responses and levels of cytokines and steroid hormones.

Changing the timing of vaccine administration to the morning “may be beneficial for the influenza antibody response in older adults, with potential implications for vaccination strategies generally,” concluded corresponding study author Anna C. Phillips. More research is needed to determine whether these differences translate to clinical disease resistance.

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