For the past nine months, COVID-19 has been spreading from person to person in the U.S. while scientists and medical professionals scramble to figure out the novel virus' patterns. Why do some people experience fatal outcomes while others barely have a fever, for example? And why do some people get it and others don't after being around the same patient zero? Fortunately, researchers may have just broken through on that discovery, and it all comes down to timing. According to a newly published scientific review of research, someone is most likely to give you COVID within five days after they first develop symptoms.
In their new review, published in The Lancet Microbe journal on Nov. 19, researchers from the University of St. Andrews examined nearly 100 studies that included around 8,000 patients who had been infected with one of three human coronaviruses that either cause COVID-19 (SARS-CoV-2), severe acute respiratory syndrome (SARS-CoV), or Middle East respiratory syndrome (MERS-CoV). The researchers compared the three coronaviruses to better understand the infectiousness of a COVID-19 patient. Read on to learn exactly what they discovered, and for areas you should be avoiding right now, read up on the 4 Places Dr. Fauci Says He Wouldn't Go Right Now.
Read the original article on Best Life.
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A symptomatic COVID patient is the most infectious five days after their symptoms appear.
Unlike SARS-CoV and MERS-CoV, a patient's viral load for the coronavirus that causes COVID-19 peaks early in the upper respiratory tract (which is thought to be the main source of transmission) during the first week of illness. Among COVID-19 patients, the researchers found the viral load is highest—meaning the patient is most infectious—five days after symptom onset.
"Our findings are in line with contact tracing studies which suggest the majority of viral transmission events occur very early, and especially within the first five days after symptom onset, indicating the importance of self-isolation immediately after symptoms start," Muge Cevik, MD, the review's lead author and a clinical lecturer in infectious diseases and medical virology at the University of St. Andrews, said in a statement. And for more ways to know if you've caught the virus, check out This Is the Easiest Way to Tell If You've Been Exposed to COVID.
And asymptomatic patients may be infectious for a shorter time period.
Cevik said that some of the studies they reviewed "suggest that asymptomatic individuals might clear the viral material from their bodies faster," even though their viral loads appear similar to those with symptoms.
"Those without symptoms may be as infectious as those with symptoms at the beginning of infection, but may be infectious for a shorter period," she explained.
However, she also noted that asymptomatic patients should still isolate for the same recommended timeframe as symptomatic patients once they test positive, as there is "limited data available on the shedding of infectious virus in asymptomatic individuals." And for more recent COVID developments, check out Dr. Fauci Says This Many People Need to Get Vaccinated to Stop COVID.
Neither symptomatic nor asymptomatic patients seem to be infectious after nine days.
The review identified 11 studies where researchers attempted to isolate the live SARS-CoV-2 virus, and they found that no study "detected live virus beyond day nine of illness" for the coronavirus that causes COVID-19—even though the virus could still be detected in their respiratory or stool samples for weeks after a positive test. That means, patients are likely no longer infectious nine days after their symptoms begin. For more useful content delivered straight to your inbox, sign up for our daily newsletter.
…Which is why it's recommended that positive COVID patients self-isolate for 10 days.
While someone may continue to test positive after a week of illness because the virus is still detectable, they're not likely to still be infectious. This is in line with the Centers for Disease Control and Prevention's (CDC) recommendations that anyone who has tested positive for COVID self-isolate for 10 days.
"These findings suggest that in clinical practice, repeat PCR testing may not be needed to deem that a patient is no longer infectious, as this could remain positive for much longer and does not necessarily indicate they could pass on the virus to others," Cevik explained. "In patients with non-severe symptoms, their period of infectiousness could instead be counted as 10 days from symptom onset." And if you think you could be sick, read up on The 4 Easy-To-Miss Symptoms That Could Mean You Have COVID, Experts Say.