COVID vs. Common Cold vs. Flu – Which one is it?
Every fall and winter – coughing, sneezing, and sniffling, and the like.
Is it the common cold?
Is it the Flu? or
It is COVID?
All 3 of these have overlapping symptoms. And COVID cases are already starting to increase in the US with the cold weather, and this is just the beginning of the 2nd surge that everyone is talking about. COVID, flu, and common colds are all caused by viruses.
These tiny infectious agents can survive only by getting inside the cells of animals or humans. There are more than 200 different viruses that can cause the common cold. The most common viruses that cause common colds are rhinoviruses and different types of coronaviruses. COVID is caused by a specific type of coronavirus called SARS-CoV-2. The specific virus that causes infection and how your body’s immune system responds to the virus determines the symptoms and severity of illness.
COVID vs Common Cold vs Flu
The main way that these viruses spread from person to person are through the tiny droplets that sick people propel when they cough, sneeze or talk. These droplets can fly six feet or more in the air, and they can spread the virus if they deposit on someone’s mouth or nose or they get inhaled into a person’s lungs. The novel coronavirus, meaning SARS-CoV-2, is also aerosolized and can actually travel up to 27 feet in the aerosolized form, and that is something I talk more about in a separate video called airborne transmission. With COVID, an infected person doesn’t need to show symptoms to spread the virus.
About 40% of viral transmission happens before infected people show symptoms. After people are infected, if they do develop symptoms, it can be for several days or the duration of their illness. And about 1/3rd of people with COVID never develop symptoms. You’re contagious the entire time you have symptoms with the common cold, but you’re most contagious right after you catch the infection before you have symptoms. You’re most contagious with the flu from the day before your symptoms start until about the fifth day of symptoms.
With any of these illnesses, it’s important to stay home when you or your child is most infectious. Viruses also spread through physical contacts like kissing or shaking hands, or when a person touches a surface (like a desk or doorknob) that has accumulated droplets from a sick person and then touches their own eyes, mouth, or nose. Viruses can live on surfaces for hours to days, although how long they remain intact and infectious depends on the virus, the surface, and the environment.
COVID is a real wild card here. There can be no symptoms, or it can be similar to the common cold. Or it can be similar to the flu. But it can also cause loss of smell, so that is somewhat of a unique symptom. And it becomes concerning when people develop shortness of breath, which is a result of pneumonia developing. So although both flu and COVID can cause pneumonia, COVID is more likely to do so.
With COVID, it can take anywhere from two to 14 days after exposure to the virus for symptoms to appear. On average, it’s 5 days. And that is if people do develop symptoms. Another unique aspect of COVID is that symptoms can start mild or even improve temporarily and then get worse. Some people continue to have fatigue and other symptoms for months after their infection, the so-called “long haulers.”
Why do some people get so sick with COVID? With COVID, the death rate ranges from 10% to 27% in people ages 85 and older but is less than 1% in those ages 54 and younger. One reason for this disparity may be differences in the aging immune system.
We know that besides age, there are other risk factors for more severe illness, like being male and having certain medical conditions like obesity, diabetes, heart disease, high blood pressure, tobacco use. In a recent October study published in NEJM, researchers identified a specific cluster of genes that make some people more prone to have severe COVID illness. They also confirmed a potential involvement of the ABO blood-group system. There seems to be a higher risk in Type A than in other blood groups and a protective effect in Type O.
Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine