A new study of the more than 300 outbreak clusters of COVID-19 in China reveals that the majority of the outbreaks were fueled by indoor transmission of the disease, while outdoor transmission was scarce.

Researchers took case reports from 320 prefectural municipalities in China, excluding Hubei Province, the initial epicenter of the pandemic. They then narrowed their scope to outbreaks with three or more cases and then "reviewed the major characteristics of the enclosed spaces in which the outbreaks were reported and associated indoor environmental issues."

New: Study of 318 outbreaks in China found transmission occurred out-of-doors in only one, involving just 2 cases. Most occurred in home or public transport. Raises key chance for states to move services outdoors (religious, gym classes, restaurants, etc). https://t.co/Isg5DGxRWa pic.twitter.com/Z5n1b52h8V — Scott Gottlieb, MD (@ScottGottliebMD) April 23, 2020

ADVERTISEMENT

The filtered data presented 318 outbreaks encompassing 1,245 confirmed cases of the virus across 120 cities. The location of the outbreaks were divided into six categories: homes, transport, food, entertainment, shopping and miscellaneous.

Nearly 80 percent of all of the outbreaks occurred in a home setting, while 34 percent came from a transportation setting. Additionally, most of the home outbreaks resulted in three to five cases.

However, researchers were only able to find one outbreak that took place in an outdoor environment, involving just two cases.

ADVERTISEMENT

"All identified outbreaks of three or more cases occurred in an indoor environment, which confirms that sharing indoor space is a major [COVID-19] infection risk," the researchers concluded in the study's abstract.

As states begin to contemplate reopening their respective economies, much has been made about when large gatherings in outdoor spaces, such as sports stadiums, would be reopened.

All of the major U.S. sports leagues stopped playing in March. President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE recently spoke with the heads of the leagues and has expressed his desire for sports to return in the fall. However, many health experts have pushed back on this, saying that the risk of another widespread outbreak if large gatherings were allowed was too great to allow sporting events with fans feasible in the coming months.