3 ms·

‘Superspreading’ events propel coronavirus pandemic

3 points by js2 6y ago

js2 6y ago
> Some people will not transmit the virus to anyone, contact tracing has shown, while others appear to spread the virus with great efficiency. Overall, researchers have estimated in recent studies that some 10 to 20 percent of the infected may be responsible for 80 percent of all cases. > In a detailed analysis of outbreaks in Hong Kong[1], for example, researchers found three distinct groups of incidents. The superspreading individuals, representing 20 percent of the total, were responsible for 80 percent of transmissions. A second group, involving about 10 percent of cases, transmitted the virus to one or two others. The final group, 70 percent, did not infect anyone else at all. > In Israel, investigators looking at 212 cases[2] concluded that they could be linked back to 1 to 10 percent of people. And in an outbreak in a South Korea office tower[3], investigators found that about 45 percent of 216 workers got the virus from a single person. In the United States, an analysis from five counties in Georgia[4] found that superspreading appeared to be “widespread across space and time,” and that 2 percent of the infected seeded 20 percent of the cases. ... > Most of these events took place in coronavirus hot spots of which most people are now aware: buildings where people live in close quarters, such as nursing homes, prisons, worker dormitories and cruise ships. There have been a fair number of clusters at meat-processing and frozen food factories, as well as at a curling event in Edmonton, Canada, leading some to speculate that temperatures could be a factor. ... > The rest of the known superspreading events were set in a hodgepodge of social venues where people gather in crowds: concerts, sports games, weddings, funerals, churches, political rallies, restaurants, shopping centers. And nearly all took place indoors, or in venues with indoor-outdoor spaces. ... > While it’s often impossible to identify the person who triggered an outbreak, there have been some commonalities among those who have been pinpointed as the likely source in studies. They tend to be young. Asymptomatic. Social. Scientists suspect these “super-emitters” may have much higher levels of the virus in their bodies than others, or may release them by talking, shouting or singing in a different way from most people. Research based on the flu, which involved college students blowing into a tube, showed that a small percentage tended to emit smaller particles known as aerosols more than others. These particles tend to hang or float, and move with the flow of air — and therefore can go much farther and last longer than larger droplets. 1. https://www.researchsquare.com/article/rs-29548/v1 https://www.researchsquare.com/article/rs-29548/v1 2. https://www.medrxiv.org/content/10.1101/2020.05.21.20104521v1 https://www.medrxiv.org/content/10.1101/2020.05.21.20104521v... 3. https://wwwnc.cdc.gov/eid/article/26/8/20-1274_article https://wwwnc.cdc.gov/eid/article/26/8/20-1274_article 4. https://www.medrxiv.org/content/10.1101/2020.06.20.20130476v2 https://www.medrxiv.org/content/10.1101/2020.06.20.20130476v...

3 points by js2 6y ago

js2 6y ago

> Some people will not transmit the virus to anyone, contact tracing has shown, while others appear to spread the virus with great efficiency. Overall, researchers have estimated in recent studies that some 10 to 20 percent of the infected may be responsible for 80 percent of all cases. > In a detailed analysis of outbreaks in Hong Kong[1], for example, researchers found three distinct groups of incidents. The superspreading individuals, representing 20 percent of the total, were responsible for 80 percent of transmissions. A second group, involving about 10 percent of cases, transmitted the virus to one or two others. The final group, 70 percent, did not infect anyone else at all. > In Israel, investigators looking at 212 cases[2] concluded that they could be linked back to 1 to 10 percent of people. And in an outbreak in a South Korea office tower[3], investigators found that about 45 percent of 216 workers got the virus from a single person. In the United States, an analysis from five counties in Georgia[4] found that superspreading appeared to be “widespread across space and time,” and that 2 percent of the infected seeded 20 percent of the cases. ... > Most of these events took place in coronavirus hot spots of which most people are now aware: buildings where people live in close quarters, such as nursing homes, prisons, worker dormitories and cruise ships. There have been a fair number of clusters at meat-processing and frozen food factories, as well as at a curling event in Edmonton, Canada, leading some to speculate that temperatures could be a factor. ... > The rest of the known superspreading events were set in a hodgepodge of social venues where people gather in crowds: concerts, sports games, weddings, funerals, churches, political rallies, restaurants, shopping centers. And nearly all took place indoors, or in venues with indoor-outdoor spaces. ... > While it’s often impossible to identify the person who triggered an outbreak, there have been some commonalities among those who have been pinpointed as the likely source in studies. They tend to be young. Asymptomatic. Social. Scientists suspect these “super-emitters” may have much higher levels of the virus in their bodies than others, or may release them by talking, shouting or singing in a different way from most people. Research based on the flu, which involved college students blowing into a tube, showed that a small percentage tended to emit smaller particles known as aerosols more than others. These particles tend to hang or float, and move with the flow of air — and therefore can go much farther and last longer than larger droplets. 1. https://www.researchsquare.com/article/rs-29548/v1 https://www.researchsquare.com/article/rs-29548/v1 2. https://www.medrxiv.org/content/10.1101/2020.05.21.20104521v1 https://www.medrxiv.org/content/10.1101/2020.05.21.20104521v... 3. https://wwwnc.cdc.gov/eid/article/26/8/20-1274_article https://wwwnc.cdc.gov/eid/article/26/8/20-1274_article 4. https://www.medrxiv.org/content/10.1101/2020.06.20.20130476v2 https://www.medrxiv.org/content/10.1101/2020.06.20.20130476v...