A San Francisco couple held a secret wedding against city rules. Then they tested positive for the coronavirus.

• A San Francisco church attempted to hold an indoor wedding despite the city's rule against large indoor gatherings.
• The couple told guests they could social distance at their discretion, the San Francisco Chronicle reported.
• At least 10 attendees, including the newlywed couple, later tested positive for the coronavirus.

On July 4, nearly 100 people arrived at Saints Peter and Paul Church in San Francisco.

They were there for a wedding — one that had been rescheduled from April due to the pandemic — in violation of San Francisco's health orders, which require religious services to be held outdoors.

The newlyweds had planned to exchange vows inside, but when a city official spotted photographers setting up and guests filtering in, he demanded that the service move outside. San Francisco currently allows up to 12 people to gather outdoors if there's no food or drink.

The group complied, but the consequences were grim nonetheless: The bride and groom, as well as at least eight other members of the wedding party, tested positive for the coronavirus, the San Francisco Chronicle reported on Sunday, citing information from two guests.

It wasn't the first time the church violated a health ordinance: On June 29, the San Francisco city attorney's office sent a cease-and-desist letter to the archdiocese after multiple local churches, including Saints Peter and Paul, hosted indoor mass.

An email from the newlywed couple obtained by the Chronicle told attendees to use discretion when it came to social distancing, handshakes, and hugs. Guests were given the option to wear face coverings.

"This is the perfect example of why public-health officials have been trying to convince people of the problems with getting together in crowds," John Swartzberg, an infectious-disease expert at the University of California, Berkeley, told the Chronicle. "And I would be shocked if we didn't see this consequence. This should be the poster child in why people should take responsibility."

A wedding against the rules

For the newlywed couple — who the Chronicle kept anonymous — Saints Peter and Paul Church is sentimental: The groom's parents and grandparents also wed there.

But by the time the new wedding date arrived, San Francisco's weekly average of new coronavirus cases had risen 250% over the prior three weeks. The city saw an average of 70 daily cases by July 4, compared to an average of 20 daily cases on June 13. San Francisco currently prohibits all large indoor gatherings with more than 12 people from multiple households.

That's because indoor gatherings increase the chances of transmission. Weddings are particularly high-risk, according to the Centers for Disease Control and Prevention, because attendees often travel from outside the local area, which brings a risk of either introducing the coronavirus to local guests or spreading the virus to other parts of the state or country.

Wedding ceremonies can also last for hours, increasing the odds that attendees will come into prolonged, close contact. And celebrations involve activities that facilitate spread, like eating, drinking, talking, and singing. This can lead people to become more lax about social distancing and wearing masks.

The night before the San Francisco wedding, the father of the bride asked guests to enter the church through the underground parking garage. The request was intended to prevent the general public from entering the church, the pastor told the Chronicle.

Some pews were blocked off to encourage distancing, and the couple opted not to distribute paper programs.

After the city official put a halt to the indoor ceremony, the wedding party — which seemed to include more than 12 people according to photos reviewed by the Chronicle — relocated to an outdoor basketball court. Guests watched the ceremony on Zoom from their cars, the Chronicle reported, then rejoined the wedding party for a backyard reception at a relative's home.

After the wedding, guests flew back to other parts of the country, including Nashville, Tennessee; Arizona; and San Diego, California. According to the Chronicle, none of the wedding party members have been hospitalized.

A recipe for superspreading

Researchers in Hong Kong have suggested that superspreader events involving indoor social gatherings may be responsible for the majority of coronavirus transmission. (A superspreading event refers to an instance in which a single infected person spreads the virus to a larger-than-average number of people.) A study from Japanese scientists estimated that the odds of person spreading the coronavirus in a closed environment is almost 19 times higher than in an open-air environment, though that research is still awaiting peer review.

Examples of superspreading at religious gatherings abound: South Korea saw a dramatic uptick in coronavirus cases in February after a 61-year-old woman attended multiple church services while infected with the virus. The woman is believed to have passed it to at least 43 others.

Coronavirus transmission also picked up steam in New York state after a lawyer in Westchester County transmitted the virus to more than 100 others in late February. The man had recently attended a funeral and bnei mitzvah at his local temple.

Then in June, at least a dozen congregants at the Westmore Church of God in Cleveland, Tennessee, tested positive for the coronavirus. The church had hoped that checking temperatures and enforcing social distancing would be enough to allow it to safely reopen. But lead pastor Kevin Page later expressed regret about not pushing harder for churchgoers to wear masks.

Other churches have seen graver consequences: In March, a pastor and his wife spread the virus to 35 church members in Arkansas. Three of the infected people died.

A CDC report said the Arkansas event demonstrated how outbreaks at church events could lead to widespread transmission in a local community. The report concluded that faith-based organizations could lower the chances of transmission by following local authorities' guidance.