London: Flu vaccinations are more effective and induce greater protective antibody responses when administered in the morning rather than the afternoon, a new study has claimed.
Researchers analysed 24 general practices between 2011 and 2013 in a cluster-randomised trial during the annual UK influenza vaccination programme.
As many as 276 adults aged over 65 years were vaccinated against three strains of influenza, either in morning surgeries (9-11am) or afternoon surgeries (3-5pm).
In two of the three given influenza virus strains, those in the morning cohort saw a significantly larger increase in antibody concentration one month following vaccination, when compared with those in the afternoon cohort, researchers said.
In the third strain, there was no significant difference between morning and afternoon, they said. "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," said Anna Phillips from University of Birmingham.
"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," said Phillips.
The influenza virus is responsible for between 250,000 and 500,000 deaths each year worldwide, researchers said.
The age-related decline in immunity reduces the ability of older adults to produce adequate antibody responses following vaccination, compromising the given protection, they said.
"A significant amount of resource is used to try and prevent flu infection each year, particularly in older adults, but less than half make enough antibody to be fully protected," said Janet Lord from University of Birmingham.
"Our results suggest that by shifting the time of those vaccinations to the morning we can improve their efficiency with no extra cost to the health service," said Lord.
The findings were published in the journal Vaccine.
