Study suggests outdoor activities pose lower coronavirus transmission risk, as states phase in reopenings

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As the weather warms and states across the country begin to open up in different phases in the wake of the coronavirus pandemic, one study suggests that transmissions from outdoor environments are rare.

The research, done by six scientists across several Chinese universities and published in early April, has not yet been peer-reviewed. It looked at more than 1,200 confirmed cases from 318 outbreaks of COVID-19 in 120 cities in China between Jan. 4 and Feb. 11 and found that outbreaks of three or more cases were largely confined to enclosed spaces, such as home and transportation.

"Among the identified outbreaks, 53.8 [percent] involved three cases, 26.4 [percent] involved four cases, and only 1.6 [percent] involved ten or more cases," researchers wrote in the study's abstract. "Home outbreaks were the dominant category (254 of 318 outbreaks; 79.9%), followed by transport (108; 34.0%; note that many outbreaks involved more than one venue category). Most home outbreaks involved three to five cases. We identified only a single outbreak in an outdoor environment, which involved two cases."

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"All identified outbreaks of three or more cases occurred in an indoor environment, which confirms that sharing indoor space is a major SARS-CoV-2 infection risk," the researchers concluded.

Former FDA Commissioner Scott Gottlieb noted states should heed the advice that outdoor activities, especially as temperatures get warmer across the country, could pose a lower risk.

"Studies suggests [sic] activities held outdoors as temperatures warm pose lower covid risk than those done in confined indoor spaces," Gottlieb tweeted on Wednesday. "As we re-open, states should look to ease rules to allow more recreational, religious, and business activities to occur outside."

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Of the 50 states, 47 of them have started some form of reopening in recent weeks, including Hawaii, Maryland, Michigan, Mississippi and Montana. These five states started some form of reopening on Thursday, including outdoor activities such as boating, tennis, fishing (Maryland), parks and outdoor recreation in Mississippi.

Hard hit states such as New York and New Jersey have also started reopening in some form, notably outdoor activities.

New Jersey recently announced that marinas, boatyard and outdoor recreation activities would be allowed. On Wednesday, Hoboken Mayor Rhavi Bhalla announced the city would launch a pilot program to create more space for "responsible outdoor activity."

New York, the hardest-hit state in the nation with more than 320,000 cases, is allowing activities to occur in the state's marinas and boatyards.

On Wednesday, New York Gov. Andrew Cuomo noted that nearly 1,300 COVID-19 patients that were admitted to hospitals in the last few days were from people out of the workforce and abiding by stay-at-home orders.

“Overwhelmingly, the people were at home," Cuomo said at his daily press briefing, calling the results "a surprise."

Gottlieb, appearing on CNBC on Thursday morning, said, "the New York data is not all that surprising," when looking at where clusters of infections have started, either via mass transit, the home or workplaces.

However, there are still concerns the coronavirus could be transmitted through the air, as some studies have shown.

“Our understanding of coronavirus transmission is incomplete and rapidly evolving,” Dr. Linda Anegawa, an internist with virtual health platform PlushCare, recently told Fox News.

Citing observations from neurosurgeons and ear-nose-throat physicians in China, Italy and Iran, as well as an article published recently in the New England Journal of Medicine, Anegawa said that there “is reason to believe that the virus causing COVID-19 may linger in microdroplets in the air.”

However, Anegawa said the likelihood of contracting the virus this way as opposed to having direct contact with an infected person would depend on the duration of exposure and viral load.

“As long as social distancing is maintained (more than six feet apart from others), going out for runs and walking is probably still safe,” Anegawa said. “The likelihood of becoming infected with a virus depends on the duration of exposure plus the viral load, meaning the amount of virus the body is exposed to. This is likely the reason why health care workers are felt to have the most severe infections with COVID-19 – they have high levels of daily viral exposure.”

Many states around the country are heavily recommending wearing masks even when social distancing can be implemented, though experts are mixed on the proposal.

A new report from a multidisciplinary group convened by the U.K.'s Royal Society concludes that wearing face masks in public, even if they are homemade cloth ones or surgical masks, can help to reduce the deadly virus's spread.

“Our analysis suggests that their use could reduce onward transmission by asymptomatic and pre-symptomatic wearers if widely used in situations where physical distancing is not possible or predictable, contrasting to the standard use of masks for the protection of wearers,” the report notes. “If correctly used on this basis, face masks, including homemade cloth masks, can contribute to reducing viral transmission.”

However, not everyone agrees with the report's conclusion.

Simon Clarke, associate professor in cellular microbiology at the University of Reading, told The Guardian that the report “falls short of delivering new evidence and too casually dismisses precautionary principle when addressing the possibility that masks and coverings could have negative effects on people’s behaviors.

“Until more evidence is delivered in either direction, that’s all advice can be based on – opinions,” he added.

Ben Killingley, a consultant in acute medicine and infectious diseases at University College London hospital, also criticized the report.

“The report is overly optimistic about the value of face coverings and it is incorrect to conclude that the evidence shows that face covering can reduce viral transmission in the community,” he said. “There is, in fact, no good evidence that face coverings achieve this.”

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As of Thursday morning, more than 3.7 million coronavirus cases have been diagnosed worldwide, more than 1.22 million of which are in the U.S., the most impacted country on the planet.

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Fox News' Alexandria Hein, Madeline Farber and Christopher Carbone contributed to this story.