Covid 19 and Common Flu

Similarities and differences


By Dr Amit Malviya & Adorelia Laitthma

Winter is soon approaching and brings with it the seasonal illnesses like common cold and flu. Flu comes every year and many people suffer mild to moderate symptoms. It’s commonly said about the common cold and flu that if you treat, it goes in one week and if you don’t it goes away in 7 days. The implication of such statements is to emphasise on the benign nature of these illnesses in majority of cases. But this year, things are different because of ongoing Covid19 pandemic. This is because the signs and symptoms of flu and Covid 19 overlap significantly and can be easily confused. As the flu season ramps up this winter every cough and sneeze will carry an extra worry: possible COVID-19 infection. It’s bound to be a confusing season for people to decide what to do when they fall ill.It is important to differentiate between these two illnesses because the diagnosis of Covid 19 in current times carries a significant burden on the individual, his/her family, health care providers and the health care delivery system.

As expected, many people will contract the seasonal flu in the coming months and once someone has symptoms which are suggestive of either flu or Covid 19, the first question that comes in the mind is regarding the testing for Covid 19. They would be anxiously wondering, whether to get themselves tested for corona virus? The testing for Covid 19 has implications for both the individual and the system. For an individual it brings a lot of stress and fear of downstream  consequences, in case he or she tests positive, including fear of adverse outcomes due to illness itself and financial issues associated with the treatment, whereas for the system each and every diagnostic kit is precious and judicious use is warranted. So far we have not reached the peak of this epidemic and it is difficult to forecast the future requirements. So triage of patients at their own level and at the level of healthcare delivery assumes importance, which is self explanatory. Following are some similarities and differences between flu and Covid 19 which may give a clue to the general public once they are suffering from symptoms.

Signs and symptoms:


Both these diseases can have varying degrees of symptoms and signs ranging from no symptoms to common symptoms like fever or feeling feverish/chills, cough, shortness of breath or difficulty in breathing, fatigue (tiredness), sore throat, runny or stuffy nose, muscle pain or body ache, andheadache. Some people may have vomiting and diarrhea, though this is more common in children than adults.


Covid 19 has certain distinguishing features from flu. Change or loss of sense of taste and smell is quiet suggestive of Covid illness. Initial symptoms of Covid 19 usually include fever, dry cough and breathing difficulty whereas with flu the initial symptoms are usually running nose followed by fever. The fever associated with Covid 19 is usually not very high but experts say it is associated with more chills and feeling of exhaustion as compared to flu.  Breathing difficulty is uncommon in flu. Another distinguishing feature is the presence of stomach upset and diarrhea which indicates more towards Covid 19 than the flu. In most of the cases ,flu is mild and transient illness lasting for less than 7 days whereas Covid 19 symptoms can last for more than 7 days and cause more serious illness in some people like elderly, heart disease patients and smokers.

How long symptoms appear after exposure and infection?


 In majority of the cases, flu symptoms develop within 1 or 2 days of exposure to the flu virus, whereas the symptoms take longer time to develop in case of exposure to Covid 19 virus. Typically in Covid 19, symptoms appear 5 days after being infected but can appear as late as 14 days after infection.

How it spreads?


Both Covid 19 and flu are viral illnesses and contagious, spreading from person to person when in close contact (within about 6 feet); spreading mainly by droplets that are released when people with the illness cough ,sneeze or talk. It is also possible to contact the virus by touching a surface or object that has virus on it and then touching his or her mouth, nose or possibly the eyes. Both flu and Covid 19 may be spread to other people by patients who never develop any symptoms or mild symptoms.


Covid 19 virus is more contagious and more of a super-spreader than the flu virus. This means that the virus can quickly and easily spread to a lot of people as compared to the flu virus.

People at high risk of severe illness:


Both flu and Covid 19 can result in severe illness and subsequent complications in elderly,people with underlying chronic medical conditions including heart problems and pregnant ladies.


The risk of severe illness and complications is more in Covid 19 as compared to flu. While complications of flu are limited to high risk people as mentioned above, the Covid 19 illness can take an adverse course even in apparently healthy individuals. Covid 19 can cause severe illness in infants ,children with underlying medical conditions (like congenital heart defects ) and a rare but severe complications of Covid 19 is the  multi-system inflammatory syndrome(MIS-C) which has been reported in previously healthy  children of school going age.

Take home message

The key differences between flu and Covid 19 are related mostly to the sequential appearance of some typical symptoms, mode and ease of spread, and risk of complications. Covid 19 seems to spread more easily than flu. Covid 19 takes longer time before appearance of symptoms and people can spread the virus longer. As compared to flu Covid 19 can cause more serious illness in some specific group of people. Another very important difference is the availability of vaccine, whereas there is a vaccine available to prevent flu, there is no vaccine for Covid 19 currently. Although these differences which are  listed above may help to distinguish between the flu and Covid 19 they are not very prominent and well demarcated and the surest way to differentiate between them is the testing . At present, it is advisable to follow the government protocols and advisories for testing of Covid 19 at population level.Therefore the preventive measures like personal hygiene, social distancing, wearing masks assume the utmost importance. They prevent both of these illnesses quiet effectively. If someone feels unwell with any of above  symptoms, the best thing to do is to self-quarantine at home – including avoiding contact with other household members and to get in touch with your health care provider to make a shared decision about Covid 19 testing.

When should people seek medical attention immediately?

There are certain symptoms which if present, one should not wait but get immediate medical attention. Breathing difficulty at rest or shortness of breath when doing activities which are part of routine life is a serious symptom. Persistent pain or pressure in the chest, confusion, drowsiness and inability to keep awake (feeling constantly sleepy), bluish lips or face include some of the other serious symptoms. The elderly, infants, those with chronic medical conditions like heart problems /kidney problems, diabetes and pregnant females should consult a doctor sooner than later.

This article is for educational purposes only and is not intended to replace the advice of health care providers. 

(Dr Malviya DM , FACC, FSCAI is from Department of Cardiology ,NEIGRIHMS & Adorelia Laitthma is Senior Research Fellow in the same Department of Cardiology)

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