How common is asymptomatic COVID-19?

There’s still so much we don’t know about the SARS-CoV-2 virus and the disease it causes — COVID-19. One of the biggest questions we still have to answer is: How common is the asymptomatic version of the disease?

As you can imagine, it’s an extremely difficult question to answer. People who don’t have symptoms don’t know they have the disease, so they don’t get tested. This creates a couple of problems…

First off, people who have asymptomatic versions of the disease can still spread it to other people. They go out into the world thinking they’re perfectly healthy and cause vulnerable people around them to get extremely sick.

Secondly, being unaware of these asymptomatic folks makes the stats researchers are compiling inaccurate. When these people aren’t accounted for, we don’t have an accurate picture of the infection rate, death rate, etc.

Luckily, we may be one (or two) steps closer to knowing the percentage of people that develop an asymptomatic version of the disease. And it turns out, asymptomatic COVID-19 is a lot more common than you might think…

80 percent of people may get asymptomatic versions of COVID

Two recent studies have confirmed that a substantial number of people develop asymptomatic cases of COVID-19…

The first study, which was published in the journal JAMA Network Open, was extremely small. It only included 78 people from Wuhan, China. And about 42 percent of them (33 people) developed asymptomatic COVID-19. The people who did were more likely to be in their 20s, 30s and early 40s. They were also more likely to be women.

The second study was a bit bigger, so the results may be more accurate (although, it was still a relatively small study). This study included 217 people who were on a cruise ship heading to Antarctica in mid-March.

Eight days into the cruise, someone on the ship developed a fever. Within the two weeks following, eight people had to be evacuated from the cruise because they were very sick. 217 people remained on the ship, and they were all tested for COVID-19. About 59 percent of those people tested positive, but far less of them had symptoms.

Of the 128 people who tested positive, only 19 percent of them had symptoms. The other 81 percent were asymptomatic.  Up until now, the Centers for Disease Control and Prevention has estimated asymptomatic cases at about 35 percent. That’s a big difference compared to the results of this study.

How to keep yourself from becoming an asymptomatic spreader

The results of these studies underscore why it’s so important to follow safety precautions right now… even if you’re feeling perfectly healthy. You should still wear a mask and stand a safe distance from other people because you might be an asymptomatic carrier of the disease… and you could spread it to someone who then becomes extremely ill.

The good news is, people who carry the disease asymptomatically are contagious for a far shorter time than people who have symptoms. According to the study out of Wuhan, asymptomatic carriers can only spread the disease for eight days, while people who have symptoms can spread it for 19 days.

So, keep taking all those important steps to keep yourself (and those around you) safe and healthy.

Sources:

1. Asymptomatic COVID-19 cases may be more common than suspected — NBC News.
2. Comparison of Clinical Characteristics of Patients with Asymptomatic vs Symptomatic Coronavirus Disease 2019 in Wuhan, China — JAMA Network Open.