80% of COVID-19 patients experience 'mild' symptoms — but that likely still involves a fever and cough

Tomohiro Ohsumi/Getty ImagesA passenger receives a temperature check before boarding a flight in Tokyo on January 21.

Just over 80% of coronavirus cases are “mild,” according to an analysis from the Chinese Centre for Disease Control and Prevention. But that doesn’t mean patients with mild symptoms of COVID-19 – the disease caused by the coronavirus – have it easy.

“COVID-19 causes more severe disease than seasonal influenza,” Tedros Adhanom Ghebreyesus, the director-general of the World Health Organisation, said in a briefing last week.

Case studies conducted so far of patients with mild cases of COVID-19 show most come down with a fever and dry cough. They may also experience fatigue and muscle aches. (A small percentage have abdominal pain and diarrhoea a day before the fever begins.)

On average, a patient’s symptoms start about five days after exposure to the virus, according to a study published Monday in the journal Annals of Internal Medicine. Nearly 98% of patients develop symptoms within 11.5 days, though about 1% start showing symptoms after 14 days. Within a few days of symptoms appearing, those infected may experience shortness of breath. Many have headaches. About 40% of patients’ lungs begin to produce fluid.

The disease’s symptoms are more severe for those with preexisting conditions, such as heart disease, diabetes, and high blood pressure.

Here’s what characterises a mild case of COVID-19.

The severity of COVID-19 cases is a spectrum. Cases are categorised as “asymptomatic,” “mild,” “severe,” or “critical.” “Mild” refers to patients that don’t need to be hospitalized.

AP Photo/John MinchilloCOVID-19 patient samples for semiautomatic testing at Northwell Health Labs on March 11 in Lake Success, New York.

Patients with severe cases are more likely to have shortness of breath, difficulty breathing, and fluid in their lungs. Usually, they will require care from a medical professional.

Mild cases can develop into severe cases if the viral infections in patients’ respiratory tracts worsen.

Critical cases will need medical care from a hospital, often in the Intensive Care Unit. These patients can exhibit respiratory failure, septic shock, and organ failure.

Fever presents in 99% of COVID-19 patients, according to a study of nearly 140 patients at the Zhongnan Hospital of Wuhan University. So almost all mild cases involve a high temperature.

Mohammad Ismail/ReutersA health worker checks the temperature of a man in Kabul, Afghanistan, on March 9.

The fever is usually the first symptom to arrive, according to the research. An increase in body temperature is a sign the immune system is fighting an infection.

Bacteria and viruses survive well in normal body temperatures of about 98.7 degrees Fahrenheit, so a mild fever of about 100.4 degrees (and a more severe fever of 103 degrees) is a way to fight off pathogens.

A cough occurs in between 60 and 80% of COVID-19 patients, arriving in tandem with a fever at the onset of the disease. It’s usually a dry cough.

Jojo Photos/Shutterstock

The study from Wuhan University found that a dry cough occurred in 60% of patients.

However, a study of 191 COVID-19 patients by doctors at two hospitals in Wuhan, China, showed that 80% of patients had coughs.

In addition, about 40% of patients began to get “sputum” in their lungs, a mixture of saliva and mucus, within a few days.

About one-third of patients also experienced dyspnea, or shortness of breath, according to the study.

About 40% of coronavirus patients experience extreme fatigue.

Associated PressMedical staff prepare beds at a temporary hospital in Wuhan, China, on February 5.

Because the coronavirus affects multiple bodily systems – the upper and lower respiratory tracts and immune system – the body gets tired and achy. Myalgia, or muscle pain, was present in 35% of cases studied.

Less common symptoms include gastrointestinal issues. In some cases, patients have reported vomiting, diarrhoea, and abdominal pain, but these issues do not seem to be common.

Claudio Furlan/LaPresse via APA medical staffer with a kit for the coronavirus test in Brescia, Italy, on March 10.

Gastrointestinal symptoms – though rare – usually develop early in the disease’s progression.

One patient with abdominal symptoms was initially placed in a surgical ward in a hospital in China because doctors didn’t suspect COVID-19. The patient then transmitted the virus to at least 10 healthcare workers and four other patients.

Patients with preexisting conditions are more likely to develop more severe cases.

P. Ravikumar/ReutersMedical staff at the Rajiv Gandhi Government General hospital in Chennai, India, on January 29.

Patients already diagnosed with heart disease who contracted COVID-19 had a death rate of more than 10%. Diabetes was the preexisting condition with the second-highest fatality rate, 7%.

Patients with the most commonly reported preexisting condition, hypertension (high blood pressure), had a death rate of 6%. Coronavirus patients with cancer had a similar death rate, according to case studies.

According to early studies, 1.2% of COVID-19 cases are asymptomatic, which means those patients experience no symptoms at all. However, they may still spread the virus.

Jim Urquhart/ReutersHealthcare workers prepare a drive-thru coronavirus-testing station in Denver on March 11.

The report from the Chinese CDC said 1.2% of patients were asymptomatic. (That’s counted separately from the 80% who have mild cases.) A higher portion of asymptomatic cases was found on the Diamond Princess cruise ship, where 380 of the 691 people tested positive but showed no symptoms.

That means the real number of asymptomatic patients could be higher, since patients who don’t realise they’re sick don’t seek testing or medical care.

If you suspect you have the coronavirus, call your doctor before leaving the house.

Erin Clark/The Boston Globe via Getty ImagesMassachusetts General Hospital in Boston prepares for coronavirus patients on February 27.

The World Health Organisation declared the coronavirus a pandemic on Wednesday. The virus has spread to more than 110 countries.

Business Insider Emails & Alerts

Site highlights each day to your inbox.

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.