Respiratory Pathogens: Is it a Cold, Flu, RSV or COVID-19?

Sniffling, sneezing and coughing have recently become increasingly common in various settings — such as healthcare facilities, homes, workplaces and schools — so it’s no surprise that the Centers for Disease Control and Prevention (CDC) has classified respiratory illness activity levels across the United States as “high.”¹ With so many overlapping symptoms, it can be tricky to determine whether it’s just a cold, or something more serious like influenza (flu), COVID-19 or respiratory syncytial virus (RSV). Knowing the difference, however, can help us manage symptoms more effectively and avoid spreading the illness to others.

Let’s explore the key differences among the common cold, flu, COVID-19 and RSV, and review some of the best ways to protect ourselves and others from the risk of infection.

Navigating the Viral Landscape

While Rhinovirus, flu, RSV and COVID-19 are all contagious respiratory illnesses, they are caused by different viruses.

The Common Cold: A Familiar Foe

The common cold, typically caused by rhinoviruses, is a mild but highly contagious illness. Symptoms often include nasal congestion, sneezing, a sore throat, and a mild cough. Unlike the flu, cold symptoms tend to develop gradually, whereas flu symptoms typically appear suddenly.² While colds rarely lead to severe complications, they can disrupt daily activities and may pave the way for secondary infections, particularly in individuals with weakened immune systems.

Flu: The Seasonal Menace

Influenza, or “flu,” is caused by influenza viruses, particularly types A and B. It can range from mild to severe and, in some cases, can be life-threatening. Flu is highly contagious, and symptoms are generally more intense than those of a common cold and may include fever, chills, muscle aches, cough, congestion, headaches and fatigue. High-risk groups — such as adults over 65 and children under two — are particularly vulnerable to serious complications, including pneumonia.³ While most individuals recover within a few days to two weeks,² the flu season typically peaks between October and February, making it crucial to stay vigilant during these months.

COVID-19: The Global Challenge

COVID-19, caused by a coronavirus (SARS-CoV-2), presents unique challenges compared to other respiratory illnesses. According to the CDC, COVID-19 spreads more easily than the flu and can lead to more severe health outcomes for some individuals.² Unlike the flu, COVID-19 does not exhibit consistent seasonal patterns. Additionally, people infected with SARS-CoV-2 may take longer to show symptoms and can remain contagious for extended periods. Symptoms range widely, from mild respiratory issues to severe pneumonia and acute respiratory distress syndrome (ARDS). COVID-19 is contagious (transmissibility is dependent on the strain) and can result in long-term health effects in some individuals (“long COVID”).⁵

RSV: A Hidden Threat

RSV does not usually cause severe illness in healthy children and adults but can cause severe illness in infants and older adults.⁶ Symptoms of RSV infection include coughing, wheezing and difficulty breathing, and can lead to more severe complications such as bronchiolitis (inflammation of the small airways in the lungs) and pneumonia. In severe cases, hospitalization may be required. RSV spreads in the fall and winter and usually peaks in December and January.⁶

Since symptoms alone cannot distinguish one respiratory infection from another, testing is necessary for diagnosis.²

Transmission: What Do They Have in Common?

Aside from several overlapping symptoms, these respiratory illnesses also share common modes of transmission:

• • Inhalation of large and small droplets: Spreads from person-to-person through respiratory droplets, when an infected person coughs, sneezes, or talks.
• • Touching contaminated surfaces: Surfaces contaminated with viral particles can facilitate indirect transmission if a person touches a contaminated surface and then touches their own mouth, nose, or eyes.

Surface Disinfection: A Critical Line of Defense

Surface disinfection plays a vital role in preventing the spread of these illnesses. Viruses like rhinovirus, flu, SARS-CoV-2 and RSV, can survive on surfaces for varying durations where they can be picked up by unsuspecting hands and transmitted to self or others⁷:

• • RSV: Up to 7 hours
• • COVID-19: 4 hours to several days
• • Rhinovirus (Cold): 4 hours to days
• • Influenza: 2 hours to weeks

This variability emphasizes the importance of regular cleaning and disinfection of high-touch surfaces, particularly in shared spaces.

Effective Disinfection Practices:

• • Use EPA-approved (and healthcare grade in healthcare settings) disinfectants with proven efficacy against these viruses.
• • Follow product directions for use for contact time to ensure pathogen inactivation.
• • Prioritize and disinfect high-touch surfaces such as doorknobs, elevator buttons, countertops and medical equipment more frequently.
• • Educate and train staff on the importance of regular disinfection and proper personal protective equipment usage.

Looking Ahead

Surface disinfection remains an essential tool in infection prevention and control, serving as an essential barrier against the spread of respiratory pathogens like cold, flu, RSV and COVID-19. While these illnesses share overlapping symptoms and transmission methods, understanding their unique characteristics is crucial for effective prevention, response and care. By adhering to best practices in hygiene, cleaning, and disinfection, we can help protect ourselves and the communities we serve.

For more information, see the additional resources and references listed below.

Additional Resources:

• Rhinovirus (Cold Virus) Pathogen Education Sheet
• RSV Pathogen Education Sheet
• Influenza Pathogen Education Sheet
• COVID-19 Pathogen Education Sheet