COVID-19 can clinically present as an asymptomatic condition (in which patients have no symptoms), a paucisymptomatic condition (where patients have few symptoms), a condition with mild to moderate symptoms, or a condition with severe and even critical symptoms.

The symptoms of the disease can vary from gastrointestinal symptoms and symptoms similar to the flu to severe respiratory symptoms and pneumonia. Since the disease is very new (the first cases came to light in December 2019), these variations in symptoms make it much harder for the general population to understand exactly what symptoms to look for and when is it important to check in with a doctor.

Data so far suggests that about 80% of the cases of COVID-19 present with mild symptoms, about 14% are severe and 5% cases are critical. 

Here is an easy guide on mild and severe symptoms of COVID-19, as explained by the World Health Organization (WHO):

  1. Mild symptoms of COVID-19
  2. Severe symptoms of COVID-19
  3. Acute respiratory distress syndrome in COVID-19
Doctors for Mild versus severe symptoms of COVID-19

Mild illness with COVID-19 presents as uncomplicated upper respiratory tract infection. A person with mild illness would have the following symptoms:

In rare cases, mild symptoms show up as nausea, vomiting and diarrhoea.

Pneumonia may or may not occur in mild infections. If it occurs, the pneumonia is non-severe in both adults and children and generally, the patient does not need any oxygen therapy.

Children with non-severe pneumonia may have cough or breathing difficulties with a faster breathing rate. The breathing rate in case of difficulty breathing in children may vary as below:

  • In children under two months of age: Greater than or equal to 60 breaths per minute.
  • In children aged two to 11 months: Greater than or equal to 50 breaths per minute.
  • In children aged one to five years: Greater than or equal to 40 breaths per minute.

In case of mild illness, immunocompromised people and the elderly may show atypical symptoms - they would have varying symptoms that may not indicate a particular condition. COVID-19 symptoms may overlap with the normal pregnancy symptoms or symptoms of complications of pregnancy such as fever, shortness of breath and fatigue.

Read more: What pregnant women need to know about COVID-19

In severe cases of COVID-19, a person would have pneumonia along with fever and shortness of breath with a suspected respiratory infection. He/she may also have one of the following: 

  • Respiratory rate of greater than 30 breaths per minute (healthy individuals breathe 12-20 times per minute).
  • Blood oxygen saturation (PaO2 or SpO2) of less than 93%: a healthy person has a blood oxygen saturation between 94% and 100%.

Children In children, severe illness manifests in the form of fever, cough, breathing difficulty and the following symptoms:

  • Central cyanosis - bluish discolouration of the tongue and lips.
  • Blood oxygen saturation of less than 90%.
  • Severe respiratory distress - the patient has severe chest indrawing and grunting.
  • Pneumonia with the following signs:
    • Lethargy
    • Unconsciousness 
    • Convulsions
    • Not being able to breastfeed
  • Increased breathing rate which may vary as:
    • Greater than or equal to 60 breaths per minute in children under two months of age
    • Greater than or equal to 50 breaths per minute in children between the ages of two months and 11 months
    • Greater than or equal to 40 breaths per minute in children between the ages of one year and five years

Read more: How to take a suspected COVID-19 patient to the hospital

Acute respiratory distress syndrome (ARDS) is a critical illness and is one of the causes of respiratory failure and death in COVID-19 patients. ARDS begins within a week of the new or worsening clinical symptoms. 

It is a life-threatening condition that develops as a result of a lung injury, pneumonia or sepsis. It is characterised by reduced oxygen levels in the body, shortness of breath and shallow breathing.

ARDS patients may have wheezing, show cyanosis or bluishness of skin due to low oxygen levels, confusion and malfunctioning organs including heart and brain. The patient shows bilateral lung opacities which can not be explained by lung nodules or lung collapse: on doing chest scans, the patient shows abnormalities in lungs which cannot be explained by lung nodules or lung collapse.

Depending on the oxygen levels, ARDS can be classified into:

  • Mild: The ratio of the partial pressure of oxygen in arterial blood (PaO2) to the fraction of inspired oxygen (FiO2) can indicate the level of hypoxia or lack of oxygen. In mild ARDS, this ratio is between 200 and 300mmHg.
  • Moderate: PaO2/FiO2 between 100 to 200mmHg
  • Severe: PaO2/FiO2 less than 100mmHg

FiO2 is the percentage of inspired oxygen. FiO2 in the air is 21% or 0.21.

ARDS needs oxygen therapy and mechanical ventilation.

In critical cases, sepsis, shock, multiple organ failure occurs which leads to death.

Dr Rahul Gam

Dr Rahul Gam

Infectious Disease
8 Years of Experience

Dr. Arun R

Dr. Arun R

Infectious Disease
5 Years of Experience

Dr. Neha Gupta

Dr. Neha Gupta

Infectious Disease
16 Years of Experience

Dr. Anupama Kumar

Dr. Anupama Kumar

Infectious Disease

Medicines / Products that contain Mild versus severe symptoms of COVID-19


  1. World Health Organization [Internet]. Geneva (SUI): World Health Organization; Clinical management of severe acute respiratory infection (SARI) when COVID-19 disease is suspected
  2. British lung Association [Internet]. London. US; Breathing and lung function tests
  3. Goh KJ, Choong MC, Cheong EH, et al. Rapid Progression to Acute Respiratory Distress Syndrome: Review of Current Understanding of Critical Illness from COVID-19 Infection. Ann Acad Med Singapore. 2020;49(1):1–9. PMID: 32200400.
  4. Matthay Michael A., Aldrich J Matthew, Gotts Jeffrey E. Treatment for severe acute respiratory distress syndrome from COVID-19. The Lancet. 2020; DOI:
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  6. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2018. Acute Respiratory Distress Syndrome (ARDS) By Bhakti K. Patel , MD, University of Chicago Last full review/revision Mar 2018| Content last modified Mar 2018 GET THE QUICK FACTS
  7. University of Colorado Denver [internet]. US; Rules on Oxygen Therapy
  8. Cascella M, Rajnik M, Cuomo A, et al. Features, Evaluation and Treatment Coronavirus (COVID-19) [Updated 2020 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan
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