Coronavirus disease (COVID-19): Similarities and differences between COVID-19 and Influenza

1. COVID-19 and influenza both predominantly affect the respiratory system.

Both infections are caused by viruses, but their effect on individuals can vary. Some have no symptoms, or mild symptoms, and others may suffer from severe disease. Both influenza and COVID-19 can be fatal. In many cases they may share similar symptoms, including cough, runny nose, sore throat, fever, headache and fatigue.

Contact your healthcare provider if you have or someone you know has any of the following severe symptoms, including:

• difficulty in breathing, especially at rest, or unable to speak in sentences
• confusion
• drowsiness or loss of consciousness
• persistent pain or pressure in the chest
• skin being cold or clammy, or turning pale or a bluish colour
• loss of speech or movement.

2. SARS-CoV-2 and influenza spread in similar ways

Both COVID-19 and influenza spread mainly between people who are in close contact with each other, for example at a conversational distance. The viruses can spread through the air from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak or breathe. Another person can then contract the virus when infectious particles that pass through the air are inhaled at short range (this is sometimes called short-range aerosol or short-range airborne transmission) or if infectious particles come into direct contact with the eyes, nose or mouth (sometimes called droplet transmission).

SARS-CoV-2, the virus that causes COVID-19, and influenza viruses spread more easily in poorly ventilated and/or crowded indoor settings, and where people tend to spend longer periods of time. This is because aerosols can remain suspended in the air or travel farther than conversational distance (this is sometimes called long-range aerosol or long-range airborne transmission).

People may also become infected when touching their eyes, nose or mouth after touching surfaces or objects that have been contaminated by the virus.  

3. Many risk factors for severe disease are common to both COVID-19 and influenza

Most people who are infected with COVID-19 and influenza do not develop severe disease, but some can get severely ill and some will die. Although this can happen to anyone, some people are at higher risk for severe disease and death when they have an infection, including:

• older adults;
• people of any age with chronic medical conditions (such as obesity, chronic diseases of the heart, lung, kidney, nervous system, liver or blood, and metabolic problems such as diabetes);
• people with immunocompromising disease (such as those that can be caused by HIV or cancer), or as a result of medical treatment (for example those prescribed steroid treatments); and
• pregnant people and those who have recently given birth.

Health and care workers are more exposed to SARS-CoV-2 and influenza viruses and therefore at a higher risk of getting infected.

• Infographic on pregnancy and COVID-19

It is important to remember that children are affected more frequently by respiratory infections, including influenza. While most of these illnesses do not cause severe disease, large number of children get infected which may also spread infections to those who are at higher risk for severe complications.

Treatment for all hospitalized patients with severe respiratory illness (due to COVID-19, influenza or another cause) includes oxygen and advanced respiratory support such as the use of ventilators. There are also specific treatments which depending on which virus is causing the illness. WHO has specific guidelines for treating both COVID-19 and influenza, which are updated frequently based on new evidence. For more information, visit Therapeutics for COVID-19 and Therapeutics for influenza.

4. Many of the same protective measures are effective against COVID-19 and influenza

Many of the same protective measures work for to prevent both COVID-19 and influenza.

To protect yourself and others against COVID-19 and influenza, the following measures have been proven to be most effective:

• wear a mask when in crowded, enclosed, or poorly ventilated areas, and keep a safe distance from others, as feasible;
• practice respiratory etiquette by covering coughs and sneezes;
• clean your hands regularly;
• stay up to date with vaccinations against COVID-19 and influenza, especially if you are at high risk for severe disease;
• stay home if you are sick; and

1. Treatments for COVID-19 and influenza are different

Since COVID-19 and influenza are different diseases caused by different viruses, their treatments are also different. However, general and supportive care, especially for mild illness, is similar for both.

Antiviral medicines are used to reduce severe complications and death for both COVID-19 and influenza. However, as the two viruses are different, so are the antivirals.

• For COVID-19, nirmatrelvir-ritonavir is strongly recommended for patients at high-risk of severe disease, although there are other options for these patients if this antiviral medicine isn’t available.
• For influenza, oseltamivir is effective, especially if administered within the first 48 hours after illness onset. Other antiviral medicines for influenza include zanamivir, peramivir and baloxavir.
• Antiviral medicines for influenza will not be effective against COVID-19, and vice-versa. 

For hospitalized COVID-19 patients who are severely ill, specific treatment options include corticosteroids, IL6 receptor blockers (such as tocilizumab or sarilumab) and baricitinib. Several other treatment options for COVID-19 are currently being evaluated in clinical trials.

Most people infected with COVID-19 and influenza do not develop severe disease and do not need any specific treatment as they recover at home. For more information about caring for someone with COVID-19 safely at home, see:

• Homecare for COVID-19: Guide for family and caregivers
• What to do if someone in your household tests positive for COVID-19
• What to do in your household if your child tests positive for COVID-19

2. Vaccines for COVID-19 and influenza are different

Vaccines developed for COVID-19 do not protect against influenza, and similarly, the influenza vaccine does not protect against COVID-19. Follow the advice of your local authorities on getting the influenza and COVID-19 vaccines. It is safe and effective to get both vaccines at the same time.

COVID-19 vaccines approved for use by WHO are proven to protect against severe illness and death caused by COVID-19 disease. More than 13 billion doses of COVID-19 vaccine have been administered globally since 2021 and the vaccines have met rigorous standards for safety, effectiveness and quality. If you do get COVID-19 or flu after vaccination, you are more likely to have mild or no symptoms than if you hadn’t been vaccinated.

Influenza vaccines are also safe and effective and have been used for decades. Influenza, like many other viruses, has different variants. Vaccines are produced each year based on the expected circulating variants in the coming flu season. It is therefore recommended to get the most up-to-date vaccination, annually. WHO recommends yearly vaccination to prevent severe influenza disease in high-risk groups including pregnant people, individuals with underlying health conditions, older adults, health workers and young children. A video on influenza vaccination is available here:

• The importance of vaccinations for influenza

WHO recommends the influenza vaccine for older individuals, young children, pregnant people, people with underlying health conditions, and health and care workers.

WHO-authorized COVID-19 vaccines are safe for adults and children 6 months and older. Those in the high-priority group for COVID-19 vaccination include older adults, adults with chronic diseases, those with immunocompromising conditions, pregnant adolescent and adults, and health and care workers. Influenza vaccines are also recommended for these same population groups.

More information can be found on the COVID-19 vaccine questions and answers page.

Yes. You need both vaccinations to be protected against both illnesses.

Yes, it is possible to have both infections at the same time. The most effective way to prevent hospitalization and severe COVID-19 and influenza is vaccination of those in the high-priority use group (older adults including those with comorbidities, other adults with chronic diseases, those with immunocompromising conditions, pregnant adolescents and adult, and health and care workers).

Continue to assess your risk for both COVID-19 and flu and follow prevention measures, such as wearing a mask when in crowded or poorly ventilated areas where a distance cannot be maintained, clean your hands regularly, and practice respiratory etiquette.