A short review of the symptoms of COVID-19

7th Jan 2021

Since December 2019, clinicians around the world have reported their findings on the symptoms of the novel coronavirus, SARS-CoV-2, the virus causing COVID-19. Over time, with access to larger populations and new information, we have edited and refined the list of symptoms. Here we present the current list as it exists at the time of writing.

 

The first reported symptoms for COVID-19

Initially, we thought that fever and dry cough occurred in the majority of patients diagnosed with COVID-19, and that runny nose and sore throat were rare.

Four cartoons showing symptoms of illness: fever, cough, runny nose, and sore throat.

Figure 1. Initial description of symptoms for patients with COVID-19. In January 2020, a study published in The Lancet reported that fever and dry cough were the most prominent symptoms, and that runny nose and sore throat were rare.

These findings came from one study published in The Lancet in January 2020 that was conducted in 99 patients who were diagnosed and admitted to the hospital with COVID-19 in Wuhan, China.1

As the number of COVID-19 cases continued to rise throughout China and spread across Asia and every continent, except Antarctica, clinicians were learning more and more about the novel virus.

 

A more comprehensive list of symptoms for COVID-19

In another study published in February 2020, the China Medical Treatment Expert Group for COVID-19 reported their findings from 1099 hospitalized patients and outpatients with COVID-19.2  

Similar to the previous study, fever and cough were the two most commonly reported symptoms in mild and severe cases. But, even in severe COVID-19 cases, only 48% had a fever on admission (however, 88.7% of patients developed a fever during hospitalization). Other common symptoms reported were fatigue and mucus production. Headache, muscle and joint pains, sore throat, and chills occurred in 10-20% of patients. Other, less commonly reported symptoms of COVID-19 were nausea or vomiting, affecting only 5% of patients, and diarrhea, occurring in 4% of patients. Shortness of breath occurred more often in severe cases.

Nine cartoons showing symptoms of illness: fever, cough, mucus production, fatigue, headache, joint paint, sore throat, chills, and shortness of breath.

Figure 2. The list of symptoms for patients with COVID-19 was expanded in February 2020. Fever and cough were still the most prominent symptoms, followed by fatigue and mucus production. Other symptoms such as headache, joint pain, sore throat, chills, and shortness of breath were added to the list.

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Common symptoms of COVID-19 in non-hospitalized individuals

Up until now, we have only talked about hospitalized patients. But most patients with COVID-19 are not admitted to the hospital. So, what are their symptoms? 

In a more recent study published in April 2020, researchers analyzed data from over 22 000 people living in Iceland to investigate the spread of COVID-19.3

The participants were recruited from the community and not the hospital. Among the 22 000 participants, 9199 were deemed at high-risk for SARS-CoV-2 infection. These included patients who were either symptomatic, were returning to Iceland from a high-risk country, or had been in contact with someone who was infected with SARS-CoV-2. Within this high-risk group of 9199, 1221 tested positive for SARS-CoV-2 infection. In the people who tested positive, fever occurred in 43% of patients, and cough occurred in 28% of patients. Body aches also occurred in about 28% of patients. Headache was another common symptom reported by COVID-19 patients in the community occurring in 21% of patients. Other reported symptoms were fatigue, runny nose, sore throat, and loss of smell or taste.

Eight cartoons showing symptoms of illness: fever, cough, runny nose, fatigue, headache, body aches, sore throat, fatigue, and loss of smell or taste.

Figure 3. In April 2020, the list of symptoms for patients with COVID-19 was updated again. High-risk patients exhibited fever, cough, body aches, and headaches. Other symptoms included a runny nose, sore throat, fatigue, and a loss of smell or taste.

 

Asymptomatic patients

But, it turns out, not everyone develops symptoms. In fact, in a subsequent analysis of the 22 000 patients included in the Iceland study, 43% of participants were asymptomatic at the time they tested positive for COVID-19.3 Although they didn’t track the participants at a later date, the authors argue it’s likely that some of these patients eventually developed symptoms. Even so, this finding highlights the potential of asymptomatic individuals contributing to the spread of COVID-19. Reported estimates of asymptomatic cases of COVID-19 range from 2.5% to 41.6%—a wide range that shows that the significance of asymptomatic transmission requires deeper investigation.

Figure 4. Asymptomatic transmission plays an important role in the COVID-19 pandemic with 2.5%–41.6% of individuals testing positive showing no symptoms.

 

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References

  1. Chen, N, Zhou, M, Dong, X, et al. 2020. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet395: 507–513. PMID: 32007143
  2. Guan, WJ, Ni, ZY, Hu, Y, et al. 2020. Clinical characteristics of coronavirus disease 2019 in China. N Engl J Med382: 1708–1720. PMID: 32109013
  3. Gudbjartsson, DF, Helgason, A, Jonsson, H, et al. 2020. Spread of SARS-CoV-2 in the Icelandic population. N Engl J Med382: 2302–2315. PMID: 32289214