COVID-19 and the flu can cause similar symptoms. However, there are several differences between them.

The novel strain of coronavirus (SARS-CoV-2) causes coronavirus disease 19 (COVID-19).

Both COVID-19 and the flu are respiratory illnesses that spread from person to person. This article will discuss the differences between COVID-19 and the flu.

For more advice on COVID-19 prevention and treatment, visit our coronavirus hub.

The symptoms of the flu and COVID-19 have a lot of overlap. They also have a few differences. One main difference is in symptom onset.

People who have the flu will typically experience symptoms within 1–4 days. The symptoms of COVID-19 often develop within 1–14 days. The median incubation period for COVID-19 is 6.57 days. However, the exact incubation period ranges across the different variants.

As a point of comparison, the incubation period for a cold is 1–3 days.

The symptoms of COVID-19 are similar in both children and adults. However, according to a 2020 review of studies, children are more likely to be asymptomatic or present with mild, cold-like symptoms, such as a headache or sore throat.

The following table outlines the symptoms of COVID-19, the flu, and a cold.

It is difficult to tell the difference between the flu and COVID-19 by looking at symptoms alone. It is also possible to have both the flu and COVID-19 at the same time. Testing is needed to confirm a diagnosis.

The symptoms of COVID-19 and flu can range from mild to severe. Both can also cause pneumonia. However, most cases of both the flu and COVID-19 are mild and can be treated and managed at home.

Initial data from the World Health Organization (WHO) suggested that 15% of COVID-19 cases are severe, and 5% are critical. People in a critical state require a ventilator to breathe.

However, according to July 2022 data from the Centers for Disease Control and Prevention (CDC), about 9% of COVID-19 cases were severe enough to require ICU care, and about 0.6% needed mechanical ventilation.

The chance of severe and critical infection is higher with COVID-19 than with the flu.

COVID-19 is also more deadly. According to the WHO, the mortality rate for COVID-19 appears to be higher than that of the flu.

Those most at risk of severe illness or complications related to these viruses include the elderly and those with underlying medical issues.

We are still learning about post-COVID conditions, also known as long COVID, that may result from infection with the new coronavirus.

Compared with the flu, research on COVID-19 remains in its early stages.

According to the CDC, getting vaccinated for COVID-19 and following recommended booster schedules is the best way to prevent severe illness.

Both SARS-CoV-2 and the flu virus primarily spread through person-to-person contact. Tiny droplets containing the viruses can pass from someone with the infection to someone else, typically through the nose and mouth via coughing and sneezing.

According to the CDC, people can transmit the flu virus to others who are 6 feet (ft) away. And the WHO recommends that people stay at least 6 ft from anyone coughing or sneezing to help prevent the transmission of the SARS-CoV-2 infection.

The WHO also reports that the virus can also live on surfaces. However, the risk of contracting the coronavirus from a surface is low.

According to the CDC, COVID-19 remains contagious for longer than the flu, but both can spread easily.

The WHO indicates that people with the flu can pass the virus on before they show any symptoms. Likewise, a person can pass on the SARS-CoV-2 infection even if they have no symptoms.

There are differences in transmission between children and adults.

According to the WHO, the transmission of the flu from children to adults is common. However, based on early data, it appears that it is more common for adults to pass the SARS-CoV-2 infection onto children. Children are less likely to develop symptoms or severe disease.

The CDC recommends that people who are not fully vaccinated wear cloth face masks in indoor public settings. If case numbers are high in the area, it may be best to wear a mask outdoors, as well. This will help slow the spread of the virus from people who do not know that they have contracted it, including those who are asymptomatic. Note: It is critical that surgical masks and N95 respirators are reserved for healthcare workers

Most people with the flu do not require medical treatment. But a doctor might prescribe antiviral drugs in some cases, which can reduce the symptoms by 1–2 days.

These antiviral drugs help the body fight the virus. They treat symptoms and reduce how long the illness lasts.

Most people with COVID-19 also do not require medical treatment. For mild cases, a person should remain home and undertake social distancing. Antiviral therapy may be prescribed for those at risk of serious illness, depending on a person’s:

  • age
  • health history
  • duration of symptoms

Early treatment can reduce symptom severity and the risk of hospitalization.

For more severe cases of COVID-19, a person may require supplemental oxygen or mechanical ventilation on a breathing machine to treat the respiratory problems that may occur.

The most effective way to prevent the flu or COVID-19 is through vaccination.

Flu shot

Many strains of influenza can cause infection. The dominant strains circulating often change from season to season.

Researchers meet each year to predict which strains will be circulating during the upcoming flu season to best match the vaccine components to the current dominant strains.

As dominant strains change from season to season, experts recommend getting the flu vaccine every year.

COVID-19 vaccination

In December 2020, the first COVID-19 vaccinations became available for emergency use in the United States for people ages 16 years and older. Depending on the vaccine manufacturer, it consists of 1 to 3 doses. A person is not considered fully vaccinated unless all doses are administered.

The CDC also recommends additional booster shots when a person becomes eligible after the initial vaccination course.

New COVID booster shots formulated to target multiple subvariants are also anticipated to become available this fall.

Other tips

Other steps to prevent the spread of these viruses include:

  • washing hands regularly
  • avoiding touching the face
  • keeping at least 6 ft away from anyone sneezing and coughing
  • covering the mouth when sneezing or coughing
  • staying at home if feeling unwell
  • working from home if possible
  • avoiding crowds and gatherings of any size
  • wearing a well-fitted mask in indoor public settings as needed

Both COVID-19 and the flu are viral infections.

Viruses are tiny microbes that survive by invading other living cells. These cells become host cells to the virus, which multiplies inside of them. They can then spread to new cells around the body.

Coronaviruses are a family of viruses that cause respiratory infections. The virus SARS-CoV-2 causes the infection that leads to COVID-19.

There are two types of viruses that cause the flu — influenza A and B. There are also several subtypes of influenza A. Any of these viruses can cause the flu.

COVID-19 and the flu are viral infections that spread through person-to-person contact. Both share similar symptoms and have the potential to lead to serious illness and complications.

The best way to prevent illness is to get vaccinated for both flu and COVID-19.

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