The sensitivity of the test for SARS-CoV-2, the virus that causes COVID-19, can vary depending on the time of day and our body’s biological clock, according to a study.
The research, published in the Journal of Biological Rhythms Tuesday, found that people were up to twice as likely to have an accurate positive test result if they tested in the middle of the day compared to at night.
The finding supports the hypothesis that COVID-19 acts differently in the body depending on our natural circadian rhythm, which has also been implicated by studies of other viral and bacterial infections, the researchers said.
The circadian rhythm is our body’s natural internal process that regulates the sleep-wake cycle and repeats approximately every 24 hours. Shedding of the COVID-19 virus – when infected cells release viral particles into the blood and mucus – appears to be most active in the middle of the day due to the modulation of the immune system by our body clock, the researchers said. .
“Taking a COVID-19 test at the optimal time of day improves the sensitivity of the test and will help us be accurate in diagnosing people who may be infected but asymptomatic,” said Carl Johnson, professor at Vanderbilt University in the States. -United.
The results indicate that the viral load is lower after 8 p.m., according to the researchers.
If people choose to get tested at that time, the risk of a false negative result could be higher, they said.
A difference in COVID-19 viral shedding throughout the day is important information that can inform how we test and treat the virus, the researchers said.
The peak shedding in the afternoon, when patients are more likely to interact with others or seek medical attention, could play a role in the increased spread of the virus in hospitals and in the community. community at large, they said.
The researchers noted that more research is needed to confirm the diurnal – that is, active during the day – nature of SARS-CoV-2.
Experimentally testing patients infected with COVID-19 to see if individuals shed the virus differently throughout the day would have important public health implications, Johnson said.
The research can be used to optimize COVID-19 testing and improve test accuracy, he added.
Researchers believe that timing considerations can be exploited to maximize the effectiveness of intervention strategies and even vaccination strategies.