Older patients given flu vaccinations in the morning rather than the afternoon produced more antibodies to fight seasonal virus strains, say researchers
GPs could save the lives of thousands of people and prevent many more from being hospitalised by administering flu jabs in the morning rather than the afternoon, research suggests.
A trial of nearly 300 pensioners seen at 24 GP practices in the West Midlands found that flu vaccinations were more effective when given at morning surgeries, with people producing higher levels of antibodies to fight off seasonal strains of the virus.
If the findings are confirmed in larger groups of patients around the country, it would hand the NHS the means to save thousands of older people from flu-related deaths or hospital visits for little to no extra cost.
“As a minimum we could save 2,400 deaths each year and many more hospitalisations in overstretched NHS hospitals,” said Janet Lord, director of the Institute of Inflammation and Ageing at the University of Birmingham, who took part in the study.
The seasonal vaccination programme carried out by GPs across the UK places a particular emphasis on patients aged 65 and over, because older people are more at risk from the flu. But despite millions of pensioners receiving the jabs, the virus still kills thousands of people every year.
When people age, their immune systems weaken. As a result, older people are often less protected by vaccines than younger people. The difference can be dramatic. When young adults are given flu jabs, 70 to 80% make enough antibodies to protect them from infection. In older people, the figure falls to 30 to 50%.
But other studies have found that as well as changing with age, the immune system varies over the course of a day. Like many other biological processes, the body’s defences may follow their own circadian rhythms.
Anna Phillips, a senior researcher on the study at Birmingham, said that flu jabs given in morning surgeries may be more effective because the immune system is more responsive in the early hours of the day. A more active immune system means more antibodies are made in the body when the vaccine is given.
For the trial, the scientists randomly assigned 276 people aged 65 and over to have flu jabs at either morning surgeries, between 9am and 11am, or at afternoon surgeries, between 3pm and 5pm. From blood samples, they then measured antibody levels against the three seasonal strains of influenza the vaccine covered. For each person, antibody levels were measured immediately before their jab, and again on a morning one month later.
The results were striking. People who had the morning flu shots had four times more antibodies against the H1N1 “swine flu” strain than those vaccinated in the afternoon. And they had 50% more antibodies against a second variety of flu, known as the B-strain. For the third flu strain, H3N2, antibody levels were much the same for both morning and afternoon shots. The results appear in the journal Vaccine.
The scientists calculate that morning and afternoon jabs both produced enough antibodies to protect people against the H1N1 and H3N2 flu strains. But for the B strain, the time of day made a difference: only those who had the morning shot appeared to have enough antibodies to fight off that particular flu variety.
While the findings are preliminary, Lord said older people may want to have their jabs in the morning in case the timing makes the vaccinations more effective.
While the work suggests a real benefit, larger studies are needed to confirm the results. “Essentially, you need a much larger study so you have enough adults to see if fewer actually get flu if they are vaccinated in the morning,” said Lord.
It is not clear why morning jabs were more effective against only two of the three flu strains. “We want to do more research to try and understand this circadian behaviour and importantly to see if it applies to other vaccinations such as the pneumonia vaccine which also does not work well in older adults,” Lord added.
Jonathan Ball, a molecular virologist at the University of Nottingham, said: “We know that a variety of factors, such as diet, sleep and exercise seem to impact on your immunity, but the fact that the amount of antibody produced following influenza vaccination differed according to whether or not the people included in the study were immunised in the morning or in the afternoon was intriguing.
“But we have to remember, differences in antibody yield that are statistically significant might not be biologically significant, and that’s the key issue. We would need to see whether or not people vaccinated in the afternoon were more likely to become infected by the virus before we could say that timing of immunisation impacts on success.”
Ben Neuman, a virologist at Reading University, said: “The most important message to take away from this study is that vaccinations work, no matter what time of day they are given.
“The idea that a six-hour delay in the start of the month-long, mostly random process of making antibodies could make any meaningful difference to the outcome doesn’t make much sense to me,” he added. “What I think happened is that, despite following what appeared to be a reasonable experimental design, there was enough of a difference between the people in the morning vaccine group and the afternoon vaccine group to skew the results.”