Study investigates if the body's immune response to infections changes with seasons

Ground breaking new research is underway at the University of Surrey in collaboration with Columbia University to investigate if the body's immune response to infectious diseases and viruses, such as COVID-19, is altered by different seasons.

Blood, stool and urine samples were taken from volunteers who visited the Clinical Research Centre at the University of Surrey during the winter and summer solstices and the spring and autumn equinoxes. During the visits volunteers remained in the laboratory for three days, in temperature- and light-controlled rooms, enabling researchers to evaluate their immune systems and circadian rhythms (natural, internal rhythms of biological processes) in order to assess whether these change from season to season. Researchers were particularly interested in the number and functionality of the volunteers' immune cells, their sleeping patterns, and their metabolite and hormone rhythms.

Initial findings from the study, which is still ongoing, have found that a subset of white blood cells that play a key role in the response of the immune system are elevated at certain times of day, indicating that the system responds differently at varying times of the day. For example, B cells that produce antibodies were found to be elevated at night. The impact of seasons on these blood cell rhythms is still under investigation.

Findings from this study will be crucial in helping to identify the best time of year to administer vaccines and whether vaccines should be administered at certain times of the day to increase their effectiveness.

Seasonal changes in the immune system may also play a role in the seasonality of infectious diseases. For example, of the four human coronaviruses identified, three have been found to be affected by winter seasonality. Researchers believe that the more we understand about how our body responds to different infectious diseases across the seasons, the better equipped we will be to deal with them.

Principal Investigator Micaela Martinez, Assistant Professor of Environmental Health Science at Columbia University, said:

Knowing the vulnerabilities of our body to diseases and viruses across the year could enhance disease surveillance and inform the timing of vaccination campaigns that will help us eradicate such infections."

Debra Skene, Professor of Neuroendocrinology at the University of Surrey and member of the study team, said:

Many infectious diseases spike at different times of the year; this could indicate that our physiological responses depend on the changing day length (photoperiod) that occurs in different seasons."

Natalie Riddell, Lecturer in Immunology at the University of Surrey and member of the study team, said:

The human immune system displays a daily rhythm, but what is less known is how this varies from season to season. By better understanding these immunological rhythms we hope to maximize the benefits of medical interventions by simply choosing the best time and date for treatment."

Findings from the study are expected to be published in 2020-2021.