En within three months, what started as a classic flu has turned into a catalog of syndromes which in their most severe forms can trigger these now famous “cytokine storms”, a runaway immune response that can cause death.
It is not uncommon for a virus to cause so many manifestations, but certain symptoms of SARS-CoV-2, such as loss of smell or blood clots, seem specific to this epidemic.
“Most viruses can damage the tissues where they breed or cause collateral damage to the infection-fighting immune system,” says Jeremy Rossman, a virology expert at the University of Kent in the UK.
Doctors suspect COVID-19 to be responsible for the hospitalization of several dozen children in New York, London and Paris with rare “multi-system” inflammatory conditions, suggesting an atypical form of Kawasaki disease or a toxic shock syndrome, which attacks the walls of the arteries and can cause organ failure.
Dozens of medical studies have described other potentially fatal consequences of the disease, including stroke and heart damage.
Researchers from Nanjing Medical University (China) have reported cases of patients who developed urinary complications and acute kidney damage.
They observed upheavals in male sex hormones, advising young men wishing to have children to consult once they were healed.
“Beware of just about everything”
Is this spectrum of symptoms unique? Not necessarily. “In a common disease, complications, even rare, will happen frequently”, decrypts for AFP Babak Javid specialist in infectious diseases of the University Hospital of Cambridge.
More than four million cases have been reported worldwide, but the true number of infections “could reach tens or even hundreds of millions,” Javid said. “If one in a thousand, even in ten thousand, develops complications, it still makes thousands of people.”
General practitioners, on the front line, were the first to try to identify patterns in the evolution of the epidemic.
“We were told at the start: fever, headache, little cough. We were added: runny nose, scratchy throat. Then it was the digestive symptoms: diarrhea, stomach aches, ”recalls Sylvie Monnoye, family doctor in Paris.
Then pain in the rib cage, loss of taste and smell, skin connections such as hives or frostbite on the toes, neurological disorders … “We started to think that we had to be wary of pretty much everything, ”comments Dr Monnoye.
Slowness of health authorities
These testimonies are supported by an internal report from the Center for Disease Prevention and Control (CDC) in the United States, which analyzed symptoms in 2,591 patients hospitalized between March 1 and May 1.
Three-quarters of the patients had chills, fever and / or cough, and almost as many had difficulty breathing, the most common symptoms of the novel coronavirus.
Almost a third complained of body aches, ditto for diarrhea; a quarter of nausea or vomiting. About 18% had headaches, 10-15% lung or abdominal damage, runny nose, sore throat.
But until the end of April, the CDC had listed only three symptoms: cough, fever and difficulty breathing. His website has since been updated, but only added a few: chills, body aches, headaches, loss of smell. The French health authorities did the same in early May.
Blood clots, kidney failure
Loss of smell (anosmia) and taste (ageusia) were only seen in 3.5% of patients in the CDC cohort, but experts believe these symptoms are more common in less severe cases. .
Anosmia and ageusia rarely occur with other viruses. As has the appearance of blood clots, which studies have linked to heart problems, liver thrombosis, pulmonary embolism and brain damage in COVID-19 patients.
“When a COVID-19 patient is severely affected, he may have problems with blood clots, which seem to be much more common than with other viruses,” according to Babak Javid, who concludes: “compared to the flu, you you are more likely to get very sick and die ”.