COVID-19 symptoms timeline details the order to watch out for

New research pinning down the likely order in which COVID-19 symptoms appear could help identify potential new cases faster, scientists claim, particularly in situations where people are uncertain whether they are in fact infected. Effective triaging of new coronavirus cases has proved difficult during the growing pandemic, in part because many people infected with COVID-19 show only mild symptoms or no symptoms whatsoever.

Researchers have known from early on in the outbreak what sort of signs of coronavirus there can be. For those who are not asymptomatic, that typically includes fever and high temperatures, nausea and vomiting, and other issues.

Still, similarities between COVID-19 symptoms, those of flus and colds, and other ailments like food poisoning and even allergies have made early diagnosis trickier. In situations where testing is available, it can leave potentially infectious people coming into contact with others as they seek out a diagnosis or, conversely, can cause people to break social-distancing protocols unnecessarily. For those who go untested, the need to immediately undertake at least 10 days of quarantine should signs of COVID-19 be spotted can be hugely disruptive.

A new study from the University of Southern California may help with that. A team from the USC Michelson Center for Convergent Bioscience's Convergent Science Institute in Cancer have come up with a chronological list of how COVID-19 symptoms manifest. It explains the likely onset of signs of the virus.

"Knowing the order of COVID-19's symptoms may help patients seek care promptly or decide promptly to self-isolate," USC points out. "It also could help doctors rule out other illnesses or plan how to treat patients."

First, they found, comes fever. That's a temperature of 100.4 degrees Fahrenheit or higher. It's followed by a cough and muscle pain. Next, comes nausea and/or vomiting. Finally, there's diarrhea.

The team relied on data from over 55,000 confirmed coronavirus cases in China from earlier this year, along with a second dataset of almost 1,100 more cases from December 2019 and January 2020. It's particularly helpful for distinguishing between COVID-19 and other respiratory illnesses, such as Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS).

"The upper GI tract (i.e., nausea/vomiting) seems to be affected before the lower GI tract (i.e., diarrhea) in COVID-19," the USC researchers say, "which is the opposite from MERS and SARS."

The hope is that, by giving patients and healthcare providers a better idea of what to look out for, new cases of coronavirus infection can be more rapidly identified, and treatment begun sooner. Given all research into different treatments – including remdesivir – suggests earlier application correlates with faster recovery, even a relatively short improvement in how soon people receive attention could lead to a significant change.

Meanwhile, as we fast approach flu season, better distinguishing between the two sicknesses will be vital in attempts to minimize the impact of both.