FILE PHOTO. Picture: David Ritchie/African News Agency(ANA)

How asymptomatic people spread Covid-19

The US Centers for Disease Control and Prevention (CDC) recently estimated that 35% of cases are asymptomatic, and that 40% of transmissions occur before people develop symptoms.

DURBAN – A new study found that asymptomatic Covid-19 patients are as likely as those with symptoms to contaminate several surfaces in their rooms.

Although there is still no clear indication of how much spread is caused by asymptomatic or pre-symptomatic patients. Public health experts say there are some telling hints that it is a major driver of this pandemic.

The researchers collected samples from surfaces such as door handles, bed rails, light switches and pillows, among others, and found that patient surroundings in the non-ICU negative pressure isolation ward for asymptomatic Covid-19 patients, or with mild disease, were heavily contaminated by the virus. The team stressed the need for thorough cleaning of areas occupied by patients.

Explaining on how Covid-19 spreads Professor Shabir Madhi, professor of vaccinology at the University of the Witwatersrand (Wits) in Johannesburg, said Covid-19 mainly spreads from one person to another via human respiratory droplets and direct physical contact.

“The infected droplets of saliva or mucus can be carried through the air when one sneezes, for example. When this happens, the viral particles emitted can be breathed in by the next person, or it can end up on surfaces that people touch, such as door handles. The same concept applies to an infected person who is asymptomatic,” he said.

The US Centers for Disease Control and Prevention (CDC) recently estimated that 35 percent of cases are asymptomatic and that 40 percent of transmissions occur before people develop symptoms. Even without knowing the exact numbers, the Centers believes that transmission from people without symptoms is a major contributor to the rapid spread of SARS-CoV-2 around the world.

An early modelling estimate suggested that 80 percent of infections could be attributed to spread from undocumented cases. Presumably, the undocumented patients were asymptomatic or had only extremely mild symptoms. Though interesting, the researchers made a lot of assumptions in that model so it is hard to judge the accuracy of that prediction.


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