What’s the Difference Between COVID-19 and the Flu?

Early on in the outbreak of COVID-19, comparisons to the flu — from symptoms to mortality rate and potential impact — were the talk of the town. As we have seen the new coronavirus spread and governments take drastic actions to slow that spread, however, it’s clear we’re facing something we’ve never seen before. In fact, it’s not necessarily helpful to compare COVID-19 with other illnesses because it’s brand new to humans.

To help clear things up, here’s what to know about COVID-19 versus the flu.

COVID-19 (SARS-CoV2) is a type of coronavirus that primarily affects the respiratory system and lungs. It causes symptoms such as fever, cough and shortness or breath, though more recent research suggests it can also cause digestive issues. Those most at risk for a severe course of illness include people over age 65 and those with underlying medical conditions.

According to the Centers for Disease Control and Prevention (CDC), there are currently more than 7,000 COVID-19 cases in the United States and nearly 100 people have died. To protect yourself and others who are more vulnerable in your community,  the CDC recommends practicing social distancing (staying home as much as possible and staying at least six feet away from others) and washing your hands often.

One of the reasons it’s tempting to compare COVID-19 to the flu is because they share an overlap of symptoms, including fever, cough and fatigue. Not to mention, we’re all familiar with the flu. However, there are several fundamental differences between COVID-19 (as a coronavirus) and influenza as a virus.

“The two viruses share some properties, but are quite different,” Bettie Steinberg, Ph.D., provost at the Feinstein Institutes for Medical Research, told The Mighty. “Both cause respiratory infections and both have RNA as their genetic structure, which makes them much more likely to mutate and change. However, their structures are quite different.”

Though more research is needed on COVID-19, one of the differences between the two viruses is how contagious they are and when. The flu, which has affected humans for thousands of years, has an incubation period of one to four days. According to the CDC, you’re infectious and at risk of spreading the flu about a day before you show symptoms and up to five to seven days after you get sick.

The flu has a smaller window when you’re infectious and typically spreads to fewer people. One person with the flu typically infects 1.3 other people. COVID-19 is much more contagious — every one person who is infected spreads it to approximately 2.5 other people even before symptoms show up.

With COVID-19, you may not start to show symptoms for two to 14 days (though five days is the average). During that whole time, while you’re asymptomatic and not showing any symptoms or mild symptoms, you are likely infectious and can spread COVID-19.

Experts believe it’s people who aren’t showing any or many symptoms moving around their communities contributing to the rapid spread of COVID-19. That’s why social distancing is so important. Steinberg said modeling our response to contain COVID-19 based on past flu epidemics isn’t a perfect example, and this may be one reason why.

Many people pointed to the mortality rate of COVID-19 versus the flu as a way to spur people into action and take the COVID-19 pandemic seriously. Indeed, COVID-19 seems to have a higher death rate than the flu.

The flu’s mortality rate calculated over the last 10 years is 0.1%, which is still between 22,000-55,000 deaths each year. Best estimates so far indicate the mortality rate of COVID-19 may be around 1.4%. The World Health Organization (WHO) has reported nearly 208,000 cases of COVID-19 around the world and more than 8,500 deaths.

The mortality rate of COVID-19 is difficult to pin down at this early stage of the pandemic. We don’t have 10 years worth of data to calculate, testing shortages worldwide mean we don’t know the true scope of COVID-19 and many factors impact the mortality rate. Countries like Italy where the health care system is overwhelmed, for example, report a higher death rate.

Another major difference between COVID-19 and the flu is the options we have for treatment and prevention. We have a flu vaccine to reduce the number of people who get that virus each year. If you get the flu, medications like oseltamivir (brand name Tamiflu) can help reduce the severity of your symptoms. We don’t have prevention or treatment options for COVID-19 yet because it’s brand new in humans.