25% to 50% of patients still spread the coronavirus even while they are ASYMPTOMATIC
“There’s significant transmission by people not showing symptoms,” said Stephen Morse, who works as an epidemiologist at Columbia University.
The CDC has “pretty much confirmed” that a large portion of COVID-19 cases will remain asymptomatic throughout the duration of their infection.
These asymptomatic carriers, Redfield added, will most likely contribute to the spread of the coronavirus, especially if they work in essential services or if they break quarantine to go to the bank or shop for groceries. This makes it all the more challenging for experts who are already having a hard time tracking the true extent of the COVID-19 pandemic.
“We don’t know all the unidentified cases out there”
Asymptomatic Patient Tracking
One of the first recorded instances of an asymptomatic carrier was studied in a research paper published on February 21 in the journal JAMA Network. It described a 20-year old woman from Wuhan, China who was able to pass the coronavirus to five of her family members despite never showing any symptoms herself.
This woman tested positive for COVID-19, but her medical examinations, which included a CT scan of her lungs, were all clear and she never became physically ill even though five of her family members went on to develop fevers, further proving that asymptomatic carriers can still transmit the disease.
According to a report from the World Health Organization (WHO), around 75 percent of people in China who were first classified as asymptomatic carriers of COVID-19 later developed symptoms. The WHO has taken to labeling these patients as “presymptomatic” carriers.
The WHO researchers later go on to say that “the proportion of truly asymptomatic infections is unclear.”
New anti-coronavirus strategies must consider asymptomatic and presymptomatic carriers
Are you asymptomatic and presymptomatic?
Further research states the average coronavirus patient begins exhibiting symptoms around five days after they’re infected. The study further warns that people shed a lot of the coronavirus during the earlier stages of infection, including the presymptomatic phase.
One study of 23 COVID-19 patients in two Hong Kong hospitals found that the viral load of these people – or how many viral particles they were shedding out into their immediate environment – peaked during the first week after they first develop symptoms. This study was confirmed by another one from Guangzhou, which stated that people were most contagious just as their symptoms started showing.
We are shedding significant amounts of the coronavirus around 48 hours before symptoms even appear
This helps explain how rapidly this virus continues to spread across the country.
This means that current COVID-19 control measures must take into account that there’s a high possibility of many presymptomatic and asymptomatic carriers of coronavirus. Even if they follow lockdown protocols to the letter, they might still need to head out to buy groceries, possibly infecting other people.