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COVID-19 and Influenza

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COVID-19 and Influenza

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People may get confused they are suffering from influenza or COVID-19. Read the article below to know in detail.

Medically reviewed by

Dr. Muhammad Zubayer Alam

Published At June 17, 2020
Reviewed AtApril 4, 2024


Since the pandemic hit the world, new information revolved around almost daily about COVID-19. Although vaccines have been developed, the coronavirus is still considered a serious illness, especially in countries deprived of vaccines. Herd immunity has also been achieved in many parts of the world to a great extent through vaccination. It is considered more severe than influenza because of the increased death rate, increased hospitalization, and increased need for ventilation support in COVID-19 patients.

Both of these illnesses cause cough, fever, and body pain and can be fatal for older adults. The causative viruses spread through respiratory droplets from one person to another. On the surface, it looks like both these infections are similar, but COVID-19 is quite different from the flu.

Many scientists have compared this pandemic to the Spanish flu, as it had similar symptoms to COVID-19 and is also a viral respiratory illness.

What Is Influenza?

Influenza, otherwise called the flu, is a viral infection that affects the nose, throat, and lungs (respiratory system). It is a self-limiting infection for most, but for some, it can result in fatal complications.

The symptoms include:

  • Fever.

  • Muscle pain.

  • Headaches.

  • Chills.

  • Profuse sweating.

  • Sore throat.

  • Runny nose.

  • Nasal congestion.

  • Dry and persistent cough.

The flu is caused by the Influenza virus (types A, B, and C). Large seasonal outbreaks are commonly caused by types A and B, and types C causes milder symptoms. When an infected individual sneezes or coughs, these viruses travel through the air in the respiratory droplets expelled by the person. Other people who inhale these droplets can get infected. Touching contaminated objects and then transferring them to the mouth, eyes, or nose can also spread this virus.

The following people are at a higher risk of developing complications of flu:

  • Children who are younger than 5 years of age (more commonly younger than 1 year).

  • Older adults (above 65 years of age).

  • People who live in old-age homes or long-term facilities.

  • Pregnant women.

  • Obese people (BMI of 40 or higher).

  • People with a weak immune system.

  • People with chronic illnesses (asthma, heart problems, liver or kidney disease, diabetes, cancer).

Influenza viruses constantly mutate and new strains appear regularly, which is why the annual influenza vaccines are not 100 % effective.

What Is COVID-19?

COVID-19 (CoronaVirus Disease 2019) is also a viral respiratory infection caused by the new coronavirus called SARS-CoV-2 (Severe Acute Respiratory Syndrome COronaVirus 2). This virus belongs to the family called coronaviruses, which are also responsible for the common cold, MERS (Middle East Respiratory Syndrome), and SARS (Severe Acute Respiratory Syndrome).

The main symptoms include:

  • Cough.

  • Fever.

  • Breathing difficulty.

  • Loss of taste and smell sensation.

  • Fatigue.

  • Body ache.

This virus also spreads from one person to another through infected droplets, which is why social distancing, good hand hygiene, and vaccination are important to stop its spread.

The following are some risk factors for developing fatal complications of COVID-19:

  • People aged 65 years or older.

  • Chronic illnesses (diabetes, asthma, liver or kidney disease).

  • Immunocompromised conditions.

  • Severe obesity.

  • Severe heart problems.

  • Blood disorders.

A number of vaccines have been developed against COVID-19. However, these vaccines only help in reducing the disease severity, and none have been attributed to providing prevention from the disease.

What Are the Differences Between These Two Infections?

As you can see, the risk factors, symptoms, and transmission of both viruses are almost the same. The following are some differences:




An infected person can spread the illness to other 2 to 2.5 people

An infected person can spread the illness to other 1.3 people

Incubation Period

1 to 4 days

1 to 14 days

Symptom Onset



Severity of Illness

Causes more severe illness (around 10 %)

Severe illness is much less likely

Death Rate

1.4 to 4.5 %

0.1 % or less

Seasonal Nature

Weather does not seem to affect this virus

More common in colder months






Many strains


Sudden and severe respiratory complications

Fewer chances of complications due to immunity build-up


Vaccination, self-isolation, and personal hygiene

Flu shot

Hospitalization Rate

19 %

2 %

The difference in symptoms:







Shortness of Breath















Sore Throat



Runny Nose



The difference in treatment and vaccine:

Treatment Options



Antiviral drug Remdesivir, monoclonal antibodies like Casirivimab, Imdevimab and Sotrovimab, immunomodulators like Tocilizumab, and corticosteroid Dexamethasone.

Vaccines are available that help in reducing the severity of infection.


Oseltamivir, Zanamivir, Peramivir, or Baloxavir

A vaccine is available, which is 60 % effective

Antibody Production:

Before vaccination:

According to the World Health Organization (WHO), only a small portion of the global population (maybe as less as 2 to 3 %) appear to have antibodies in the blood, showing they have been infected with COVID-19. A study in the Netherlands conducted on 7000 blood donors, found that just 3 % had antibodies, which is up to 14 % in Germany and France. In Italy, it is below 10 %. In New York, it is about 25 %.

After vaccination:

As the vaccinations has been started almost two years back and most of the people have got their vaccinations done. This brings very high hopes that this pandemic is ending and that lives are back to normal. Initially, the threshold for developing herd immunity was set at 60 % to 70 %. It has now been increased to 80 % to 90 %. Also, the huge difference between the percentage of the population that has been vaccinated in different countries poses a great problem in achieving the threshold level of immunity.

A person with an influenza infection or immunization with an influenza vaccine can develop antibodies against influenza, and it can give protection for at least six months.

How Can These Infections Be Prevented?

Vaccination is the most effective way to prevent the spread of influenza. Therefore, get vaccinated and in addition, do follow these preventive tips, which will also protect a person from other respiratory infections:

  1. Do wear a mask when going out, and a person should make sure to cover the nose and mouth properly. Also, discard the used masks properly to prevent cross-infection.

  2. Form a habit of washing the hands thoroughly and regularly.

  3. Do not touch the face (mouth, nose, or eyes) without washing the hands first.

  4. Maintain a minimum of 6 feet distance from a visibly ill person.

  5. Rest and stay home.

  6. Work from home as much as possible.

  7. Do not go to overly crowded places or gatherings.

  8. Sneeze or cough while covering the nose and mouth with the arm or a tissue.


COVID-19 and flu have similar symptoms, but influenza occurs faster, and symptoms vary, but COVID-19 more often leads to critical illness or death. As most people with COVID-19 are asymptomatic, SARS-CoV-2 spreads faster. Influenza commonly affects children and can result in severe complications, while COVID-19 has been seen to affect children less likely. As Influenza viruses have been around for a long time and with vaccines available, our bodies have some degree of immunity to fight even the new strains of this virus. Vaccination for COVID-19 started around 2 years back, and community immunity has been achieved quite well.

With the ongoing pandemic already claiming thousands of lives, timely vaccination with regular and booster doses is the foremost method to prevent its severity. Practicing social distancing and maintaining good personal and domestic hygiene are other effective ways to curb its escalation further.

Frequently Asked Questions


What Do COVID-19 and Influenza Have in Common?

Both COVID-19 and influenza are respiratory viral infections. Both are transmitted as droplet infections from an infected person to others and both share certain common symptoms of illnesses such as fever, cough, difficulty in breathing, and sore throat.


Does the Same Virus Cause Both Influenza and COVID-19?

No, influenza and Covid-19 are caused by different viruses. Influenza commonly known as flu is caused by influenza viruses, while COVID-19 is caused by a variant of coronavirus called SARS-CoV-2.


How Long Does the Influenza Virus Last in the Air?

Influenza viruses survive in air droplets for several hours. Their survival rate in droplets increases in lower temperatures. However, influenza viruses do not last for a  longer duration on surfaces (hands) and fall to minimal levels within five minutes.


How Can One Determine if an Individual Is Affected by COVID-19 or Influenza?

Since both  flu and COVID-19 have similar symptoms, it is difficult to identify the type of infection based on symptoms.  Specific testing is needed to confirm the diagnosis. RT-PCR (Reverse transcription polymerase chain reaction) helps in detecting the exact type of virus.


What Helps to Recover From Influenza?

Adequate rest and plenty of fluid intake are essential for recovering from the flu. In case of severe infection, supportive care is needed.  Appropriate medications are given in higher-risk conditions to avoid complications.


Which Medicine Is Used to Treat Influenza?

Antiviral drugs are prescribed as medications to treat influenza illness, particularly for individuals who are at higher risk (asthma, diabetes, heart disease) of developing serious flu complications. Flu antiviral drugs should be started at the earliest to treat individuals who are hospitalized due to flu infections.


Does Influenza Flu Gets Cured by Itself?

For the majority of healthy people, the flu is a self-limiting illness that gets resolved on its own by the effective functioning of one’s own immune system. Symptoms appear within one to three days of exposure to the influenza virus and last up to five to seven days. But in elderly people or individuals having other comorbid conditions like diabetes., supportive care may be needed.


When Does a Cough Start With COVID?

Mostly, the first symptom to appear is fever during Covid. Usually, Cough appears within 2 to 14 days after getting exposed to the virus


Is Going Out Recommended During Influenza Infection?

Going outside should be avoided during influenza infection. In case of developing flu symptoms, one should stay at home and avoid contact with other people to prevent the spread of infection. Also, inadequate rest could increase the severity of the infection.


How Is Influenza Detected?

Several accurate tests are available in specialized laboratories to detect influenza. RT-PCR (Reverse transcription polymerase chain reaction), viral culture assays, and immunofluorescence assays are specific tests for influenza. The test sample includes swabbing the inside of the nose and back of the throat by a trained healthcare provider.
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Dr. Muhammad Zubayer Alam
Dr. Muhammad Zubayer Alam

Pulmonology (Asthma Doctors)


hand hygieneinfluenzacovid-19vaccinationsevere acute respiratory syndrome
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