Question: Wondering about sudden onset of symptoms…..how common is it and what’s the most likely abrupt signal that you might be infected, constituting a medical emergency?

Answer: COVID symptoms can appear gradually in some individuals and suddenly in others. The main self-check that serves as an early sign of infection is loss of smell. I think about that when I smell my coffee in the morning… mmmmm coffee. Doctors warn (as does CDC’s clinical guidance) that mild symptoms can quickly turn serious. When it comes to medical emergencies, CDC recommends that you call 911 and seek emergency care immediately if you experience any of the following: trouble breathing, persistent pain or pressure in the chest, new confusion, inability to wake or stay awake, and/or bluish lips or face.

COVID Symptoms vs. Common Cold and Influenza Symptoms

We talked about COVID symptoms way back in our Q&A of 7/6 #Symptoms. Since then, more evidence has accumulated that loss of smell is a common symptom that often presents suddenly (pooled estimates suggest 44% of cases experienced loss of smell based on subjective measurements; 77% based on objective measurements). This symptom helps differentiate COVID from other widely circulating viruses, like the common cold or flu. Cough, fever, and shortness of breath are also common COVID symptoms (Figure 1). Fever helps differentiate COVID from the common cold. Still, there’s a lot of overlap with influenza symptoms. The journal, Frontiers in Public Health published in August, “Modeling the Onset of Symptoms of COVID-19,” which showed that COVID is more likely to begin with a fever while influenza is more likely to begin with cough and fatigue. That’s one more way to try and differentiate COVID from influenza. When it comes to symptom onset, colds usually come on gradually, flu usually comes suddenly, and COVID can come gradually OR suddenly. If you experience loss of smell, fever, cough, or shortness of breath, please be sure to call your doctor, who will likely recommend that you get tested for COVID. Obviously, if you have any other health concerns, call your doctor too!

Figure 1. Symptoms of COVID (from CDC)