Morning vaccinations may elicit greater immune responses

Recent findings published in the journal Vaccine suggest that certain vaccinations may be more effective in generating immune system responses when administered in the morning, rather than later in the day.

The study, released by an investigative team from the School of Sport, Exercise and Rehabilitation Sciences at the University of Birmingham in the United Kingdom, found that morning recipients of a flu vaccine experienced a significantly larger increase in antibody concentration one month after the vaccination, compared to individuals given the same vaccine in the afternoon.

“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, Ph.D., the principal investigator of the study. “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.”

Between 2011 and 2013, 24 general medicine practices in the West Midlands, U.K. were analyzed in a cluster-randomized trial. A total of 276 adults aged 65 and older were vaccinated against three different strains of influenza, either in morning surgeries—between 9:00 a.m. and 11 a.m.—or afternoon surgeries—between 3 p.m. and 5 p.m.

In order to eliminate unwanted variables, participants in the study completed a questionnaire adapted from a 1991 health study to collect socio-demographic information and health behaviors. Smoking, alcohol consumption and sleep duration were accounted for, in addition to the team collecting a sample of each participant’s blood.

In two of the three given influenza virus strains, those in the morning group saw a difference in antibody concentration compared to those in the afternoon group. In the third strain, no significant difference was recorded between morning and afternoon.

The study’s results are perhaps most notable for possibly being proof that changing the variables of vaccine distribution can actually alter the effectiveness of the vaccine. In the past, interventions to improve the outcomes of vaccines have been met with little success. Variables such as exercise routines and additives to vaccines have yielded no notable change in vaccine potency, or were simply found to be impractical in a public health setting.

Although the study’s findings are significant, a concrete conclusion has yet to be formed as similar studies have been conducted with differing results. In a 1988 study, a hepatitis B vaccine administered between 1 p.m. and 3 p.m. resulted in a higher antibody response when compared to the same vaccine being administered between 7:30 a.m. and 9 a.m. Results conclusive with the Birmingham study have been found in a prior study, though in that study only 164 individuals were vaccinated. That study was also not randomized and used a mixed sample of both influenza and hepatitis A vaccinations. The introduction of the study stated that “It is possible that the best time of day for vaccination may be different for different vaccines, as they stimulate different types of immune response for protection, e.g. thymus-dependent versus thymus-independent responses.” The thymus is an organ in the immune system where T cells—a subtype of white blood cells—develop.

According to the study’s abstract, the influenza vaccination is administered as a part of a seasonal vaccine program carried out by medical professionals in the U.K. as well as in many other countries. Despite this, the influenza virus is responsible for 250,000 to 500,000 deaths annually. The older adult demographic consists of the majority of these deaths as well as influenza-related hospitalizations.

This is due to the fact that decline in immunity to the influenza virus is correlated to aging, where the inability for older adults to produce adequate antibody responses following vaccination compromises its effectiveness.

“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 Professor Janet Lord, who served as a co-investigator on the study. “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.”

The research team will now look to investigate their findings on a larger scale by doing another study on patients afflicted with conditions such as diabetes and kidney disease.