Why Covid-19 test results taken during daytime varies from that at night?

A new study has supported the hypothesis that Covid-19 acts differently in the body based on our natural circadian rhythm.

A study has claimed that SARS-CoV-2, the virus that causes Covid-19, may act differently depending on the time of day and the body's circadian rhythms, suggesting that Covid test results may vary based on the time of the day. Led by researchers at Vanderbilt University Medical Center, the study found more accurate positive test result when the test was conducted in the middle of the day compared to at night.

According to the study published in the Journal of Biological Rhythms, a Covid patient's viral load is lower after 8 p.m, and so there is a higher chance of a false-negative result when the test is done at night. The finding may help prevent false test negatives, which can be harmful for patient who might not seek medical care due to their negative test result.

Coronavirus is more active during the day

It is believed that Covid-19 acts differently in the body based on our natural circadian rhythm. The new study also supports this hypothesis. It suggested that the virus shedding is more active in the middle of the day due to modulation of the immune system by our biological clock.

"Taking a Covid-19 test at the optimal time of day improves test sensitivity and will help us to be accurate in diagnosing people who may be infected but asymptomatic," said Carl Johnson, Professor of Biological Sciences, at Vanderbilt, as quoted by IANS.

The finding that the peak time for viral shedding appears to be in the afternoon is very important, as patients are more likely to interact with others or seek medical care at this time, which could increase the likelihood of transmission of the virus in hospitals and the wider community. However, the researchers noted that further research is needed to confirm the diurnal nature of the virus.

Covid-19 situation in India

Meanwhile, India recorded 13,451 new Covid-19 cases and 585 new fatalities in the last 24 hours. With this the country's death toll has gone up to 4,55,653. In the same period, as many as 13,05,962 Covid-19 tests were conducted across the country. So far, 103.53 crore people in the country have been vaccinated in the country, the Union Health Ministry said on Wednesday.

(With inputs from agencies)