The ‘circadian clock’ is an endogenous 24-hour clock recognised in all biology that, along with a seasonal clock (summer/winter), impacts on how environmental challenges are handled, including the outcome of infectious diseases and vaccinations.
The COVID-19 pandemic, caused by SARS-CoV-2 coronavirus, is a global crisis with unprecedented challenges for public health. Vaccinations are being rolled out to slow the incidence of new infections and reduce disease severity. Circadian rhythms along with sleep quality have been proposed to influence vaccine-mediated immunity to a range of pathogens. It is noteworthy that morning vaccination against the respiratory pathogen influenza A virus in the elderly was associated with significantly higher levels of anti-viral antibodies. Based on the published literature we anticipate that immune responses to SARS-CoV-2 vaccines will show a diurnal pattern.
We will evaluate associations between the time-of-day of SARS-CoV-2 vaccination and sample collection with the magnitude of anti-Spike antibody titres in a cohort of health care workers who received either Pfizer or AstraZeneca vaccines.