Difference Between the Common Cold, Flu, COVID-19, and RSV

Summary

• The common cold, flu, COVID-19, and RSV are viral respiratory infections with overlapping symptoms.
• Symptom similarity means testing or clinical evaluation may be needed in some cases.
• Severity and risk vary by virus, age, and health status.
• Some commonly searched comparisons lack high-quality evidence and are clearly noted.

What Are Respiratory Viral Infections?

Respiratory viral infections affect the airways and, in some cases, the lungs. They commonly spread through close contact with infected people, including exposure to respiratory droplets from coughing or sneezing and contact with contaminated surfaces.

Some infections remain mild and limited to the upper airways, while others can progress to more serious lower respiratory disease.

Overview of the Four Common Respiratory Viruses

Common Cold

• Very common viral illness
• Usually mild
• Most people recover without medical treatment

Influenza (Flu)

• Viral respiratory illness
• Typically causes more intense symptoms than the common cold
• Can lead to complications such as pneumonia

COVID-19

• Viral respiratory illness caused by SARS-CoV-2
• Illness severity ranges from mild to severe
• Some individuals experience prolonged or recurring symptoms

RSV (Respiratory Syncytial Virus)

• Common respiratory virus
• Most infections are mild
• Can cause serious illness in infants, older adults, and people with certain chronic conditions

Shared Symptoms Across These Infections

Symptoms that commonly overlap include:

• Cough
• Runny or stuffy nose
• Fever
• Fatigue

Because these symptoms occur across multiple viruses, symptoms alone may not reliably identify the cause.

Key Differences Supported by Evidence

Typical Severity Patterns

• Common cold: Usually mild
• Flu: Often more intense than a cold; may cause pneumonia
• COVID-19: Severity varies widely
• RSV: Often mild, but potentially severe in high-risk groups

Cold vs RSV: What the Evidence Shows

• RSV can closely resemble a cold, especially in adults
• Worsening symptoms rather than gradual improvement may suggest RSV
• Wheezing or difficulty breathing is more commonly associated with RSV
• RSV poses higher risk to infants and older adults than the common cold

Contagiousness: What Is Known

Evidence confirms that these viruses spread through respiratory contact.
However, precise comparisons of contagious periods between the cold, flu, COVID-19, and RSV are not consistently supported by high-quality evidence.

Testing and Diagnosis

• Laboratory testing can help identify flu, COVID-19, or RSV
• Testing is often considered when symptoms are severe or worsening
• Not all mild infections require testing

Treatment Overview

• Most viral respiratory infections are managed with supportive care
• Supportive care may include rest, fluids, and fever-reducing medications
• Antibiotics do not treat viral infections
• Antiviral medications are used only in specific situations

When to See a Doctor

Seek medical evaluation promptly if any of the following occur:

• Trouble breathing or shortness of breath
• Bluish or gray lips or skin
• Severe dehydration
• Symptoms that worsen instead of improving
• High or persistent fever

Infants, older adults, and people with weakened immune systems or chronic conditions may need evaluation earlier.

Prevention Strategies

Evidence-supported prevention measures include:

• Staying up to date with recommended vaccines
• Frequent handwashing
• Avoiding close contact with sick individuals
• Covering coughs and sneezes
• Staying home when ill

Frequently Asked Questions

APA Reference List

Centers for Disease Control and Prevention. (2024, April 16). Healthy habits: Coughing and sneezing. https://www.cdc.gov/hygiene/about/coughing-and-sneezing.html

Centers for Disease Control and Prevention. (2024, April 24). About rhinoviruses. https://www.cdc.gov/rhinoviruses/about/index.html

Centers for Disease Control and Prevention. (2024, August 13). About influenza (flu). https://www.cdc.gov/flu/about/index.html

Centers for Disease Control and Prevention. (2024, September 17). How flu spreads. https://www.cdc.gov/flu/spread/index.html

Centers for Disease Control and Prevention. (2024, September 17). Similarities and differences between flu and COVID-19. https://www.cdc.gov/flu/about/flu-vs-covid19.html

Centers for Disease Control and Prevention. (2024, October 15). About common cold. https://www.cdc.gov/common-cold/about/index.html

Centers for Disease Control and Prevention. (2024, September 11). People at increased risk for flu complications. https://www.cdc.gov/flu/highrisk/index.htm

Centers for Disease Control and Prevention. (2025, March 10). Symptoms of COVID-19. https://www.cdc.gov/covid/signs-symptoms/index.html

Centers for Disease Control and Prevention. (2025, April 23). COVID-19. In CDC Yellow Book. https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/covid-19.html

Centers for Disease Control and Prevention. (2025, July 8). How RSV spreads. https://www.cdc.gov/rsv/causes/index.html

Centers for Disease Control and Prevention. (2025, July 8). RSV in adults. https://www.cdc.gov/rsv/adults/index.html

Centers for Disease Control and Prevention. (2025, July 24). Long COVID signs and symptoms. https://www.cdc.gov/long-covid/signs-symptoms/index.html

Centers for Disease Control and Prevention. (2025, August 18). Clinical overview of RSV. https://www.cdc.gov/rsv/hcp/clinical-overview/index.html

Centers for Disease Control and Prevention. (2025, September 2). Treatment of flu. https://www.cdc.gov/flu/treatment/index.html

Centers for Disease Control and Prevention. (2025, December 19). Influenza antiviral medications: Summary for clinicians. https://www.cdc.gov/flu/hcp/antivirals/summary-clinicians.html

Centers for Disease Control and Prevention. (n.d.). Antibiotics aren’t always the answer [PDF]. https://www.cdc.gov/antibiotic-use/media/pdfs/Antibiotics-Arent-Always-the-Answer-P.pdf

Mayo Clinic. (2023, May 24). Common cold: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/common-cold/symptoms-causes/syc-20351605

National Foundation for Infectious Diseases. (n.d.). How to tell the difference between flu, RSV, COVID-19, and the common cold. https://www.nfid.org/resource/how-to-tell-the-difference-between-flu-rsv-covid-19-and-the-common-cold/

National Library of Medicine. (2022, November 16). Common cold. MedlinePlus. https://medlineplus.gov/commoncold.html

National Library of Medicine. (2025, January 1). Common cold. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/article/000678.htm

National Library of Medicine. (2025, April 1). Upper respiratory tract [Image]. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/imagepages/19378.htm

National Library of Medicine. (2025, April 6). Lower respiratory tract [Image]. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/imagepages/19379.htm

National Library of Medicine. (2025, July 25). Respiratory system [Image]. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/imagepages/9248.htm

World Health Organization. (2025, February 28). Influenza (seasonal). https://www.who.int/news-room/fact-sheets/detail/influenza-%28seasonal%29