Friday, April 3, 2020

No sign of coronavirus? Here's why you could still carry it (and spread it)

Studies show that carriers with moderate or no symptoms are a key component of COVID-19 spread...
One of the main issues surrounding the coronavirus (COVID-19) outbreak is the speed with which the virus spreads. Although much of the emphasis has been on isolating patients with symptoms of active disease, a number of recent studies indicate that carriers with mild or no symptoms may help spread the virus.
We know that up to 80% of COVID-19 cases have moderate symptoms. Complicating matters, pulmonologist Joseph Khabbaza, MD, says that signs can not be apparent for up to two weeks. And since these non-specific symptoms (fever, sore throat, cough, diarrhea) that represent other more common illnesses such as flu or cold, many of those infected — especially early in the outbreak — did not know they were carrying the virus.
One research looked back at the initial spread in China and found that people who had contracted the virus but had mild symptoms helped accelerate the spread.
The research used a mathematical model to predict the initial distribution of COVID-19 through hundreds of cities in China. Researchers found that 86% of infections had occurred in the U.S. prior to January 23, 2020. The Centers for Disease Control (CDC) gave a Level 3 travel warning to Wuhan, China, which was unidentified.
Since so many of these unidentified cases displayed mild or even no signs, the study reported that such carriers were at risk of "exposing a far larger portion of the population to virus than would otherwise have occurred." The study also concluded that "unidentified infections were the source of infection for 79% of recorded cases."
The research from Japan highlights the number of carriers of COVID-19 that have no symptoms. One was on the Diamond Princess cruise ship, which was put under quarantine in Japan at the beginning of February 2020 when a former passenger tested positive for the virus was discovered.
The study found that 634 of the 3,063 tests given to quarantine passengers returned positive. It is estimated that about 17.9 percent of these successful patients have no symptoms.
Such findings, says Dr. Khabbaza, highlight the value of following instructions from government and medical agencies on security measures such as quarantine and social distancing. Because so many carriers have little to no symptoms, it is difficult to determine how many people actually carry the virus. This fact makes preventive action all the more necessary.
Since the virus can become airborne through respiratory droplets when an infected person coughs, sneezes, or talks near you (within six feet) and can move by person-to-person contact, social isolation from others, irrespective of symptoms, will help break the chain of transmission.

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