Visiting bars and restaurants increases the risk of contracting the COVID-19 infection, while inviting guests for dinner also plays a major role in transmission, French researchers said on Thursday. 

Their study further bolsters evidence that socialising and eating out at public places are more dangerous than activities such as using public transport or shopping, AFP reported. 

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This comes as Europe and the United States struggle to contain a surge of infection rates at the start of the holiday season, marked by parties and family get-togethers. 

Researchers from France’s Institut Pasteur were looking to identify a pattern in factors like professions, modes of transport, places visited, in order to differentiate participants who had contracted the virus from those who did not. 

“We saw an increased risk associated with frequenting bars and restaurants,” said Arnaud Fontanet, the lead author of the research, an epidemiologist and a member of the scientific council advising the government. 

Although the study, called ComCor, has not been peer reviewed, it has guided the French government’s response to the virus. The study was carried out in the months of October and November, during a period of curfew with even more stringent restrictions following soon after, which led to most establishments being partially or completely closed.

Fontanet told AFP that because of the closure of bars and restaurants, it was difficult to determine their exact role in the transmission, while acknowledging closing these businesses was a “sensitive move”. 

French cafes and restaurants have remained closed even after nationwide restrictions were eased earlier this week.

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ComCor researchers interviewed 3,400 people infected with COVID-19 and 1,700 others who did not have the virus.

They found that frequenting restaurants, bars or gyms was associated with an increased risk of infection, whereas using public transport and visiting shops were not.

Health authorities across the world have advised people to avoid crowded indoor spaces as scientists increasingly agree that the new coronavirus can travel in fine clouds of particles known as aerosols that can collect in poorly ventilated rooms.

A September survey by the US Centers for Disease Control and Prevention found that adults with positive coronavirus test results were about twice as likely to report having eaten at a restaurant in the previous two weeks than those with negative results.

In November, a study in the journal Nature found that restaurants, gyms and cafes account for most COVID-19 infections in the United States.

Using mobile phone data from 98 million people, researchers found about 10% of venues accounted for more than 80% of cases.

The ComCor research also tried to pinpoint different circumstances of infection, with surveys of 25,600 infected individuals using health insurance data.

It showed that “meals play a central role in these contaminations”, as people sat close to each other without masks.

“Private meetings — families, friends — are the main source of infection,” Fontanet said.

“If people have friendly dinners at their homes rather than going to a restaurant, it doesn’t make a difference.”

The researchers stressed the importance of organising such gatherings in “the safest way possible” to protect vulnerable people over the holidays.