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The World Health Organization instigated a backlash from public health officials during a June 8 press conference when Maria Van Kerkhove, WHO technical director for the COVID-19 Answer said it is "very rare" for asymptomatic carriers of COVID-19 to spread the virus. The statement came after Kerhove said that in countries tracking asymptomatic cases, they "follow contacts and cannot find secondary transmission".
A day later, the WHO went back and clarified the statement, with Kerkhove stating that the WHO "does not yet have this answer" as to whether and how often asymptomatic carriers of COVID-19 spread the virus.
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Now, many people are confused about whether or not asymptomatic carriers can spread COVID-19 - but the question isn't really about that. It is safe to assume that asymptomatic carriers can spread the disease, based on early and ongoing studies of the nature of COVID-19.
The bigger question is around how contagious These cases really are - especially now that the US is seeing one massive increase in cases relaxed after lockdown restrictions.
Remember that information about the novel coronavirus is changing rapidly: we will with new facts every day. This article explains the concept of asymptomatic COVID-19 cases at the time of writing. We will update this story as more information becomes available.
What it means to be an asymptomatic carrier
If you are an asymptomatic carrier of a disease, it means that you have the disease but are not showing any Symptoms.
In the case of COVID-19, it can pose a serious threat because of the way this virus spreads: people who do not know they have the virus may not stay home or take precautionary measures such as walking away wear a mask or stay six feet apart from others if they leave their homes.
There is a lot of confusion about what "asymptomatic" really means - part of it comes from a lack of data on asymptomatic carriers of COVID-19, but much of it comes from the many different uses of the word "asymptomatic".
People can become infected with the novel coronavirus and be truly asymptomatic - meaning the virus infects them and goes its course without ever causing symptoms.
Then there are people who are "presymptomatic," which refers to the time between infection and the onset of symptoms. With many viruses, people are contagious in pre-symptomatic phases, and we know this is true for COVID-19.
Someone can be presymptomatic for several days, and when they are not self-insulating During the presymptomatic phase (which of course is not in the foreground) they could have passed the virus on to anyone with whom they came in close contact.
Finally, there are mild cases of COVID-19 where an infected person may exhibit acute symptoms such as a mild cough, mild body ache, or other symptoms typical of the common cold. These people may never know they have COVID-19 because their symptoms are not severe enough to warrant a test and therefore they will never be diagnosed.
Unfortunately as a result of one @WHO Statement and @ CNBC Reporting today there is still considerable confusion about the asymptomatic story. Conflict with pre-symptomatic status.
Let's first define these two groups pic.twitter.com/R52dsNSHB0- Eric Topol (@EricTopol) June 9, 2020
People with mild cases may not feel sick enough to stay home from work or avoid running errands. After all, life doesn't stop because of a cold - before the pandemic, despite having a mild cold, it was quite common to keep up with your daily obligations and many people still work with that attitude.
"Asymptomatic" has been used to describe all of the above scenarios, which is not helpful in determining whether or not asymptomatic transmission of COVID-19 is significant.
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Can Asymptomatic People Spread COVID-19?
In general, asymptomatic people can spread their disease. This presumably also applies to the novel coronavirus, although officials do not yet know how often COVID-19 is spread by asymptomatic carriers.
Studies have shown that people can be contagious for the first few days after the virus appears, before showing symptoms. One study actually estimated that more than 40% of novel coronavirus cases were transmitted in the presymptomatic phase. In a study analyzing samples from sailors on the USS Theodore Roosevelt, about 20% of those infected said they never developed symptoms.
What We Learned From Epidemiology: A lot of news that seems good is actually bad news. Some examples:
- Joshua Gans (@joshgans) June 8, 2020
A survey by the CDC reports that 54% of people who tested positive for COVID-19 couldn't remember how they got it. The remaining 46% of respondents who tested positive said they did close contact with someone who was sickas a family member before they developed the disease.
This indicates that the majority of people could have gotten COVID-19 from an asymptomatic person with whom they had been in close contact or from a symptomatic passer-by, such as someone coughing at the grocery store near you.
The report concludes that this ambiguity "underscores the need to isolate infected individuals, track and review contacts while the community is in progress, and preventive measures such as social distancing and the use of fabric face covers".
So it's clear that people can get the disease but remain symptom-free. It's also clear that people who develop symptoms can potentially spread the virus before they know they have it.
Coronavirus Reopening: What It Looks Like When Lockdowns Around The World Are Eased
How many people with coronavirus are asymptomatic?
Estimates of the percentage of asymptomatic coronavirus cases vary widely. Experts have estimated that between 25% and 80% of people with COVID-19 never develop symptoms. Here's a look at some research on asymptomatic COVID-19:
- As early as January 2020, researchers found that presymptomatic transmission can likely explain secondary cases of COVID-19.
- In April 2020, researchers suggested that the virus was most contagious before or when symptoms started.
- A May 27 study in the Journal of American Medicine reported that more than 40% of study participants who tested positive for COVID-19 were asymptomatic.
- Another study found that 104 out of 128 (81%) positive cases on a cruise ship showed no symptoms.
- In New Orleans, Louisiana, a study conducted by a city hospital system found that 75% of infectious people were asymptomatic.
Why are these results important?
If people have COVID-19 and don't know, it is They are unlikely to take maximum precautions to prevent the virus from spreading.
Some officials have raised concerns that it would discourage the WHO's original statement that asymptomatic spread is "very rare" Wearing masks and social distancingThis could make the spread of COVID-19 much worse if asymptomatic people can easily transmit the virus. Because of this, many experts argue that it makes sense to assume that asymptomatic spread is a threat.
How does COVID-19 spread?
As a quick reminder, SARS-CoV-2, the virus that causes the disease COVID-19, spreads via respiratory droplets such as saliva and mucus. This means that it mainly spreads when people with the virus cough, sneeze, and talk in the presence of other people. Direct contact with sick people also spreads the virus.
It is also possible for COVID-19 to spread when people touch surfaces that have the SARS-CoV-2 virus on, although the CDC says that is not the main mode of transmission.
According to the CDC, RNA from the virus has been found in other body fluids and by-products such as blood and stool, but experts still don't know if COVID-19 can spread via these substances.
The best way around prevent the spread of COVID-19 practice good personal hygiene (e.g. Wash your hands often), stay at home when you can (and definitely when you are sick), Wear face covering When going out, avoid contact with other sick people.
The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a doctor or other qualified health care provider with any questions about a disease or health goals.
