美国德州A&M大学华裔学者领导的研究发现，减少Covid-19传播的最佳方法是戴口罩

[lindamy]

8 min ago
The best way to reduce Covid-19 transmission is to wear a face mask, study finds
From CNN’s Andrea Kane

Airborne transmission is the main way the new coronavirus spreads, and wearing a mask is the most effective way to stop person-to person spread, according to a new study by a team of researchers in Texas and California.

The researchers, led by Renyi Zhang from the department of Atmospheric Sciences at Texas A&M University, compared Covid-19 infection rate trends in Italy and New York both before and after face masks were made mandatory. Both locations started to see infection rates flatten only after mandatory face masks measures were put in place.

They calculated that wearing face masks prevented more than 78,000 infections in Italy between April 6 and May 9, and more than 66,000 infections in New York City between April 17 and May 9.

“Wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic,” they wrote in a report published Thursday in the Proceedings of the National Academy of Sciences .

The researchers undertook their analysis to gauge the effectiveness of different strategies for stopping the spread of infection and to determine how the virus is mainly spread.

Viruses can spread by direct contact when a person coughs or sneezes on another person; indirect contact, when a person coughs or sneezes on an object that is then touched by another person; or in the air via large droplets that fall quickly to the ground and tiny droplets, called aerosols, that can travel several feet and hang in the air for a while.

To figure out how the virus is mainly transmitted, the researchers analyzed trends in the infection rates in three epicenters — Wuhan, China; Italy; and New York City. They also looked at mitigation measures that were being used in those locations, such as extensive testing, quarantining, contact tracing, social distancing and mandatory use of face masks.
Then they compared the timing of when those measures were put in place. In China, all of the measures were put in place at the same time. In contrast, New York and Italy saw different measures being put in place at different times. This allowed the researchers to assess their relative effectiveness.

They found infection rates in Italy and New York City only started to slow after face masks were made mandatory, not after lockdown was put in place in Italy or after stay-at-home orders went into effect in New York.

There has been much confusion about the effectiveness of face masks.

“Advice on the use of face masks was not issued until April 6, 2020 by the WHO, claiming that it is important only to prevent infected persons from viral transmission by filtering out droplets but that it is unimportant to prevent uninfected persons from breathing virus-bearing aerosols,” Zhang and colleagues wrote. When people wear face masks, they are protecting others more than they are protecting themselves.

But the researchers said the evidence shows masks work to slow spread.

“Face covering prevents both airborne transmission by blocking atomization and inhalation of virus-bearing aerosols and contact transmission by blocking viral shedding of droplets,” they write. “On the other hand, social distancing, quarantine, and isolation, in conjunction with hand sanitizing, minimize contact (direct and indirect) transmission but do not protect against airborne transmission.”

 

[春夏秋鼕]

早点抄作业，不至于这么惨

 

[向问天]

这事真需要科学家研究么？
难道不是常识？

 

[stoneway]

谭医生不会抄作业。

早点抄作业，不至于这么惨

 

[9981]

Common question
Is the coronavirus disease airborne transmitted?

According to current evidence, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes. In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.

 

[贵圈]

没有逻辑思维? 不对, 西方教育很重视逻辑,
医疗医学专业人士, 政府人员防疫专员的逻辑, 他们都是精英.

那为啥, 这种简单的逻辑判断会出错?

谁知道?

我才是利益. 政治利益和经济利益. 出卖了自己的灵魂.

 

[quecan]

我的天！ 这么久， 科学家在科研经费的支持下， 终于得出了这么一个巨大的 科研成果。

 

[lindamy]

谷歌翻译：哈佛医学院的最新研究成果

武汉的卫星图像可能表明冠状病毒最早在8月传播

这项尚未进行同行评审的研究发现，与去年同期相比，2019年夏末和2019年秋季，武汉五家医院的停车场的汽车数量明显增加;并且在中国的百度搜索引擎上增加了与传染病相关的关键字搜索

。。。。。。。。。。。。

中国外交部发言人华春莹周二表示，她还没有看过这项研究，“但是，如果有人仅根据交通模式等表面因素得出这样的结论，那我就荒唐可笑了，”他称这项研究方法“几乎没有水密性”。

她说：“有太多针对中国的阴谋论，这太不公平了。” “目前，国际社会最紧迫的任务是尽一切努力来控制大流行的蔓延并挽救更多的生命。”

使用2018年10月的图像，研究人员在武汉最大的医院之一天佑医院的停车场计数了171辆汽车。一年后的卫星数据显示，同一批车辆中有285辆汽车，增长了67％，同期武汉其他医院的交通量增长了90％。

“个别医院在2019年秋季和冬季均具有相对较高的天数。但是，在2019年9月至2019年10月之间，六家医院中有五家的相对日量最高，这与百度针对该医院的搜索查询水平升高相吻合。 “腹泻”和“咳嗽”这两个词。”

他说：“现在我们不能清楚地证明是什么驱动了这些信号，但它增加了越来越多的证据，表明某些事情正在正式被承认之前就发生了。”

布朗斯坦和他的团队说：“虽然我们无法确定数量的增加是否与新病毒直接相关，但我们的证据支持了其他最新研究，这些发现表明在华南海鲜市场上鉴定之前就已经出现了。” “这些发现也证实了这种病毒是在中国南部自然出现的假说，并可能在武汉集群发生时已经在传播。”

布朗斯坦说，也很容易错过大流行的早期迹象。 “如果在美国发生同样的事情，我们很可能也会错过这些信号。因此，我认为这与我们需要加强公共卫生工作并加强公共卫生监督的想法有关。

美国于1月初发现，一种基于呼吸道的流行病正在武汉蔓延，但要等到美国在西雅图发现首例已知病例后，这将需要数周的时间，联邦政府将开始采取任何行动。



Satellite images of Wuhan may suggest coronavirus was spreading as early as August

By Shelby Lin Erdman, CNN

Updated 6:41 PM ET, Wed June 10, 2020

(CNN)Satellite images of hospital parking lots in Wuhan, China, as well as internet search trends, suggest the coronavirus may have been spreading in China as early as last August, according to a new study from Harvard Medical School.

The study, which has not yet been peer-viewed, found a significantly higher number of cars in parking lots at five Wuhan hospitals in the late summer and fall of 2019 compared to a year earlier; and an uptick in searches of keywords associated with an infectious disease on China's Baidu search engine.

The reseachers note they can't directly link the traffic volume to the virus; even if there was an increase in traffic to hospitals, it doesn't mean a new virus was the cause. There has been no other evidence to show the virus was circulating in China in the late summer.

The timeline in the new paper suggests signs of the novel coronavirus outbreak emerged well before the currently understood start. The first cases in Wuhan were detected in mid-December, and Chinese officials reported cases of pneumonia to the World Health Organization on December 31. Chinese scientists identified the pathogen as a new strain of coronavirus on January 7.

WHO and China have faced criticism, including from President Donald Trump, of their handling of the virus early on.

Chinese Foreign Ministry spokeswoman Hua Chunying said Tuesday she she hadn't seen the research, "but I think it's outrageously absurd if anyone comes to such conclusion only based on superficial elements like the traffic patterns," calling the research methods "hardly watertight."

"There have been so many conspiracy theories against China, which is so unfair," she said. "The most pressing task for the international community at this moment is to do everything to control the spread of the pandemic and save more lives."

Piecing together a complicated puzzle

In the new paper, researchers saw "a steep increase in volume starting in August 2019 and culminating with a peak in December 2019," the team, led by Boston Children's Hospital Chief Innovation Officer John Brownstein, wrote in a preprint posted on Harvard's DASH server.

Using images from October 2018, the researchers counted 171 cars in the parking lots at one of Wuhan's largest hospitals, Tianyou Hospital. Satellite data a year later showed 285 vehicles in the same lots, an increase of 67%, and as much as a 90% increase in traffic during the same time period at other Wuhan hospitals.


AP report claims China knew of pandemic danger in Wuhan even as officials downplayed risk of virus

"Individual hospitals have days of high relative volume in both fall and winter 2019. However, between September and October 2019, five of the six hospitals show their highest relative daily volume of the analyzed series, coinciding with elevated levels of Baidu search queries for the terms 'diarrhea' and 'cough'," they wrote.

"This is all about trying to piece together a complicated puzzle of what was taking place at the time," Brownstein told CNN.

"The data is actually especially compelling because we saw increases in people searching for gastrointestinal disease -- diarrhea -- which were increasing at a level that we hadn't seen at all, historically, and we now know now that gastrointestinal symptoms are a really important marker for Covid," he added. "A huge percentage of people that actually end up testing positive in Wuhan actually had presented symptoms of diarrhea."

Paul Digard, a professor and chair of virology at University of Edinburgh, told the Science Media Center in the UK that using hospital traffic images to detect disease is "an interesting idea with some validity."

"However, it's important to remember that the data are only correlative and (as the authors admit) cannot identify the cause of the uptick," Digard said. "By focusing on hospitals in Wuhan, the acknowledged epicentre of the outbreak, the study forces the correlation."

Satellite tracking surveillance of infectious diseases

Using "validated data streams" for respiratory disease surveillance isn't new and it's also a technique employed by intelligence agencies.

"Both the idea that hospital parking lots or business can be used can be a relative indicator for something happening in a population," Brownstein said. "We actually published on this years ago where we showed that hospitals in Latin America got super busy during flu season. You could predict flu season just by looking at the parking lots."

And that was the idea in this study, he said.


ABC News: US intelligence warned of China's spreading contagion in November

"Now we can't prove clearly what was driving some of these signals but it sort of adds to a growing body of evidence that something was happening ahead of when it was officially recognized," he said.

"While we cannot confirm if the increased volume was directly related to the new virus, our evidence supports other recent work showing that emergence happened before identification at the Huanan Seafood market," according to Brownstein and his team. "These findings also corroborate the hypothesis that the virus emerged naturally in southern China and was potentially already circulating at the time of the Wuhan cluster."

It's easy to miss the early signs of a pandemic, too, Brownstein said. "If the same thing happened in the US, it's very possible that we could miss these signals, as well. So I think it's all about the idea that we need to strengthen our public health efforts and also strengthen our public health surveillance.

The United States found out in early January that a respiratory-based epidemic was spreading through Wuhan, but it would take weeks before the first known case was identified in the United States in Seattle and the federal government would begin to take any action.

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"We also have the challenges of the lack of testing in this country, so signals were probably missed here, as well, that transmission was happening and we didn't know about it either," Brownstein said.

More than 7 million people have since been infected with the deadly virus worldwide, according to Johns Hopkins University, with more than 404,000 global deaths and more than 110,000 deaths in the US.

Steven Jiang and Jamie Gumbrecht contributed to this report.

 

[shu]

这个还需要研究。