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How to Differentiate Between the Common Cold, the Flu, and COVID 19

As the weather gets colder, in any normal year, we would be preparing to enter into cold and flu season by ensuring that facilities are stocked with cold and flu medication and preparing to deal with an uptick in students presenting symptoms and needing to be seen to be excused from class. This year is anything but normal, and with tensions already high regarding COVID 19 in classrooms, it has become vitally important to be able to differentiate between the common cold, influenza, or “flu”, and COVID 19.

Similarities and Differences

Below is a list of symptoms listed by the CDC to characterize each disease. While this is a good tool for reference, you should check in with your local DPH guidelines for any changes or modifications before making any decisions for your health or the health of your students.



Common Cold




Very Uncommon

Very Common







Common, but Mild

Common, More Severe

Very Common, Severe


Common, but Mild

Common, More Severe

Common, More Severe


Common, but Mild

Common, More Severe

Very Common, Severe





Action To Take

Can be controlled with over the counter medication and rest

Should be monitored by a doctor for complications

Seek medical assistance immediately, and completely quarantine

The Flu Versus The Common Cold

The differences between the common cold and the flu are far easier to spot than those between the flu and COVID 19. The Center for Disease Control suggests that a cold will have a gradual build and then decline of symptoms over the course of 7 to 10 days, often including sneezing, congestion, and a sore throat and occasionally fatigue, aches, or a slight cough. The flu, on the other hand, will have a sudden onset of symptoms, including a telltale fever, aches, fatigue, congestion, and headache.

Colds are usually very mild and can be managed with minimal time away from school or work and over the counter medication. The flu, on the other hand, will require more time away and should be monitored by a doctor to prevent serious complications such as pneumonia from developing.

The Flu Versus COVID 19

It becomes more difficult to tell the difference when talking about the flu and COVID 19. According to the CDC, Both the flu and COVID 19 can cause fevers, chills, a cough, difficulty breathing, fatigue, sore throats, nasal congestion, muscle aches, headaches, vomiting, or diarrhea. COVID 19 does have a few hallmark symptoms that you can watch for, including a loss of taste of smell and intense difficulty breathing.

Both are characterized by a sudden onset of symptoms, but COVID 19 has been known to have a variety of ways symptoms can emerge, even to the point of causing an acute medical emergency seemingly out of nowhere.

The biggest difference is that, more often, symptoms of the flu will be milder and more short-lived, meaning that a patient will be able to function normally within 5 to 7 days of developing the illness. Based on our current knowledge of COVID 19, however, the symptoms appear to be more severe and will impact the patient’s life for a long time afterward.

Identifying Based on Symptom Development

While it takes more than 24 hours for symptoms to appear for all three illnesses, symptoms of the common cold will appear slowly over a few days, symptoms of the flu will usually suddenly appear less than 4 days after infection, while symptoms of COVID 19 can take up to 2 weeks to appear, and then can be sudden but building. If you can identify the time of exposure, differentiating between the two becomes significantly easier. However, because the flu and COVID 19 are extremely similar in terms of symptoms, the best way to know with certainty what you’re dealing with is to be tested.

If there is any uncertainty at all as to which illness is causing the symptoms, the patient should be properly quarantined following national guidelines, with minimal contact with the rest of their household and no contact with anyone outside of the home. 

Preventative Steps to Take

It’s important to note that co-infection is a very real threat with all three of these illnesses, and can cause major complications if it occurs, especially in already at-risk groups such as the elderly, the immunocompromised, and people with respiratory diseases such as asthma or COPD. Therefore, it is more important than ever to make sure that students, faculty, staff, and teachers are vaccinated against the flu. For more information about vaccinations, see the CDC’s Vaccinations and Immunizations page.

As a preventative measure for all three illnesses, frequently touched surfaces should be sanitized frequently, and students, faculty, and staff, as well as parents and guardians, should all be washing their hands frequently for at least 20 seconds with soap under warm water.

If you’d like to give your school the benefit of a full-time on-site medical professional to help keep your students and faculty safe, please see our Health Coordinator Program. You can also see this catalog from the NACCHO of local health departments for further information and resources.

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