Asymptomatic COVID-19: Five things to know

We answer some commonly asked questions about the spread of coronavirus by people who do not develop symptoms.

The Technological Vaccine Center of the Federal University of Minas Gerais is Testing a Vaccine against the Coronavirus (COVID - 19) and also Testing Diagnosis Kits
Scientists worldwide are working on testing and developing a vaccine for the new coronavirus [File: Pedro Vilela/Getty Images]

Since the first cluster of cases of the novel coronavirus was reported in China last December, scientists have been racing to get a better understanding of the highly contagious disease, COVID-19, and how to stop its spread.

The coronavirus is transmitted from person to person through direct contact, droplets of saliva while coughing or discharge from the nose when sneezing. 

But there is ongoing scientific debate and research concerning the contagion passing on from asymptomatic carriers.

What is asymptomatic?

Asymptomatic means a person has been infected by the virus, but does not feel sick or develop any symptoms.

This is different from pre-symptomatic, which means a person does not show the symptoms in the early stages of the illness but develops them later on.

For those who are not asymptomatic, the time between infection and the onset of symptoms can range from one to 14 days. Most infected people show symptoms within five to six days.

According to the World Health Organization (WHO), the most common symptoms of COVID-19 are fever, fatigue and a dry cough. Some patients may experience aches and pains, sore throat, diarrhoea, or a loss of smell or taste.

Can asymptomatic people spread coronavirus?

The general consensus among health officials and experts is: Yes.

WHO has maintained that asymptomatic people can transmit COVID-19 but more research is required to determine the extent of the transmission.

Dr Naheed Usmani, president of the Association of Physicians of Pakistani Descent of North America (APPNA), told Al Jazeera: “Asymptomatic people are generally not being screened, at least in the United States. They can definitely spread the disease.”

INTERACTIVE: Coronavirus COVID-19 symptoms explainer

How can asymptomatic carriers spread the virus?

Like symptomatic and pre-symptomatic cases, asymptomatic people can shed the virus in many ways, including through spitting, coughing and sneezing.

Infection can also be passed on through direct contact with others or by contaminating surfaces and objects.


“When you speak, sometimes you’ll spit a little bit,” Anne Rimoin, an epidemiology professor at UCLA’s School of Public Health, told CNN.

“You’ll rub your nose. You’ll touch your mouth. You’ll rub your eyes. And then you’ll touch other surfaces, and then you will be spreading virus if you are infected and shedding” the virus.

Are asymptomatic COVID-19 carriers less contagious?

This remains unclear and more research is required.

Based on current evidence, WHO says asymptomatically infected individuals are less likely to transmit the virus than those who develop symptoms.

Dr Usmani concurs. She said: “If infectivity correlates to the dose of the virus exposure, then asymptomatic carriers would be shedding lower viral copies.”

How can you protect yourself?

It is recommended to wash your hands frequently with soap and water, keep surfaces and objects clean and wear face masks, especially in crowded places.

Where possible, maintain a safe distance between yourself and others – particularly if they are coughing and sneezing – and avoid touching your face, eyes and mouth with unwashed hands.

Follow Saba Aziz on Twitter: @saba_aziz

Source: Al Jazeera