What does it really mean when we talk about “mild” COVID-19 infections?

Clinical Symptoms Treatments

 It sure doesn’t feel all that mild…

We hear you! Many people who have had a “mild” COVID-19 infection might disagree with that descriptor! There is a lot of talk about mild, moderate, and severe COVID-19 infections, but what does that actually mean? These distinctions have a specific medical meaning and do matter, because they impact what kind of treatments are available to you and how best to take care of yourself. But it is important to remember that “mild” infections can still feel terrible and cause a lot of illness, missed work, impact families and communities, and result in long-term complications like Long COVID.

There are clinical definitions to help guide clinicians in classifying and ultimately treating COVID-19 infections. The NIH gives these definitions:

➡ Asymptomatic Infection: Individuals who test positive for SARS-CoV-2 but who have no symptoms.

➡ Mild Illness: Individuals who have at least one symptom of COVID-19 (like fever, cough, sore throat, headache, muscle pain, nausea, vomiting, diarrhea, loss of taste and smell) but who do not have shortness of breath, difficulty breathing, or abnormal chest imaging.

➡ Moderate Illness: Individuals who show evidence of lower respiratory disease during clinical assessment or imaging and who have an oxygen saturation (SpO2) ≥94% on room air at sea level. This means they have shortness of breath, trouble breathing or abnormal imaging of the lungs but still have normal blood oxygen levels.

➡ Severe Illness: Individuals who have SpO2 <94% on room air at sea level, a ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) <300 mm Hg, a respiratory rate >30 breaths/min, or lung infiltrates >50%. This one is getting more technical, but this is a person who has abnormal blood oxygen levels, are breathing way too fast, or lung imaging shows that more than half of the lungs are filled with something denser than air (like fluid, protein, blood, or pus).

➡ Critical Illness: Individuals who have respiratory failure, septic shock, and/or multiple organ dysfunction. These folks are typically in the Intensive Care Unit (ICU).

Most often, people with asymptomatic, mild, or moderate illness can be treated at home. They may be candidates for monoclonal antibody treatment or antiviral medications (this depends on risk factors for developing severe illness). People with severe or critical illness are usually hospitalized and may be treated with steroids, remdesivir, and immunomodulating drugs (like baricitinib or tocilizumab). People who have severe or critical illness may also need oxygen treatment as well as help breathing, medications to keep the blood pressure up, help eating or getting fluids in the body, and other supports.

Just because someone has a “mild” COVID-19 infection, it doesn’t mean they feel hunky-dory. People often feel terrible: physically, mentally, and emotionally. It is frequently described as “I feel like I got hit by a bus.” They may miss days or weeks of work or school, need to isolate from friends and family, or struggle financially to afford INSERT SO MANY THINGS HERE (like childcare, food, housing, or medications). Even asymptomatic and mild infections can lead to Long COVID with prolonged and even debilitating symptoms. Mild COVID is no joke.

Thanks to Judy from Philadelphia and Ashleigh from Chicago for the question!

Stay Safe. Stay Sane.

Those Nerdy Girls


NIH definitions of COVID severity

NIH COVID Treatment Guidelines

IDSA COVID Treatment Guidelines

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