It seems that the list of coronavirus symptoms – from uncomfortable to fatal – grows every week.
What started as a familiar flu-like accumulation of chills, headaches, and fever has rapidly expanded over the past three months to a catalog of syndromes that affect almost every organ in the body, from the brain to the kidneys.
The new corona virus can also boost the immune system and trigger an indiscriminate attack – known as a cytokine storm – on pathogens and their human hosts.
"Most viruses can cause disease in two ways," said Jeremy Rossman, a virology lecturer at the University of Kent.
"They can damage tissue in which the virus replicates, or they can cause damage as a side effect of the immune system that fights the disease."
For example, doctors suspect that COVID-19 has been behind the hospitalization of several dozen children in New York, London, and Paris in recent weeks who have been diagnosed with a rare inflammatory disease similar to Toxic Shock Syndrome.
The painful illness mainly affects young children, attacks arterial walls and can lead to organ failure.
Dozens of medical studies in the past few weeks have detailed other potentially fatal effects such as strokes and heart damage.
Researchers from the Urological Department at Nanjing Medical University, who wrote in Nature Reviews this week, described patients who develop severe urinary complications and acute kidney injuries.
They also observed "dramatic changes" in male sex hormones.
– "1 in 10,000 still a lot" –
"After recovery from COVID-19, young men interested in children should get advice on their fertility," they concluded.
Does this mean that COVID-19 causes a uniquely wide range of symptoms? Not necessarily, say virologists and other experts.
"When it is a common disease, complications are rare," Babak Javid, an infectious disease advisor at Cambridge University hospitals, told AFP.
There are nearly 3.8 million confirmed COVID-19 cases around the world, but the actual number of infections – taking undetected and asymptomatic infections into account – "will be ten, possibly hundreds of millions," he said.
"So if one in 1,000, or even one in 10,000, gets complications, that's still thousands of people."
It is also known that some of the rarer symptoms associated with COVID-19 have been caused by influenza, which causes hundreds of thousands of people to die worldwide each year.
For the new corona virus, general practitioners at the forefront worldwide were the first to search for patterns for the developing pandemic.
"In the beginning we were told to watch out for headaches, fever and a mild cough," recalls Sylvie Monnoye, a family doctor in central Paris for almost three decades.
"Then they added a runny nose and a scratchy throat. Then digestive problems, including abdominal pain and severe diarrhea."
The list continued to grow: skin lesions, neurological problems, severe chest pain, loss of taste and smell.
– a feeling of confusion –
"We were beginning to think that we should assume everything," said Monnoye, dressed from head to toe in protective clothing.
Some patients were so scared that they crouched in the corner of their office and were afraid of touching something or getting too close.
An internal report by the United States Centers for Disease Control (CDC) with a symptom breakdown for 2,591 COVID-10 patients hospitalized between March 1 and May 1 suggests such individual reports.
Three quarters of the patients had chills, fever and / or cough, almost as many showed shortness of breath.
These are by far the most common COVID-19 symptoms.
Almost a third complained of flu-like muscle pain, while 28 percent reported diarrhea and a quarter reported nausea or vomiting to the media, according to the internal report.
About 18 percent had a headache, while 10-15 percent had chest or abdominal pain, runny nose, sore throat, and / or a feeling of confusion.
Less than one percent of the CDC cohort had other symptoms, including seizures, rashes, and conjunctivitis.
Health authorities have been slow to alert the public to this multitude of potential impacts.
– loss of smell –
By the end of April, the CDC had only listed three on its website: cough, fever and shortness of breath. The update contained only a few: chills, muscle aches, headaches, and loss of smell or taste. France's health officials released a similar update on May 5.
A loss of smell and taste was found in only 3.5 percent of the patients included in the CDC report. However, experts suspect that these symptoms – for unknown reasons – are far more common in less severe cases where people have not been hospitalized.
Monnoye said it was one of the most common symptoms she encountered and agreed that it was "probably related to a milder form of the disease".
"I don't have patients with these symptoms who have had serious complications," she said.
According to experts, the loss of taste and smell is extremely rare with other types of viruses.
Another group of symptoms that rarely occurs in flu patients appears to be due to blood clots.
Heart problems, liver thrombosis, pulmonary embolism and brain damage in COVID-19 patients have been attributed to such clots in a number of recent studies. Others have described kidney failure and even plastered dialysis machines.
"When you are very sick with COVID, there can be problems with blood clot formation, and that seems to be much, much more common than with other viral infections," added Javid.
"Compared to influenza, you are much more likely to get seriously ill and die."
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)