The success of the Los Angeles Lakers and Dodgers are bringing fans together in the LA area and that may be helping drive an uptick in coronavirus cases, Los Angeles County’s top health official said Monday

The Lakers won the NBA championship two weeks ago and the Dodgers are one game away from winning the World Series. Their run through the playoffs has prompted watch parties and celebrations.

Los Angeles County is the nation’s largest, with 10 million residents, and positive cases there increased this month from an average of 940 per day to nearly 1,200 last week, Public Health Director Barbara Ferrer said.

Health officials have warned of a second wave of virus cases and Ferrer said LA County’s increase wasn’t immediately apparent because of a backlog of cases due to technical issues with data collection systems.

“We’ve been seeing, first, very low case numbers a couple weeks ago and then in the last few days very high case numbers,” she said. “Now that we’ve processed the backlog of cases from the state, and analyzed the numbers by episode date, it is clear that our cases increased. This increase is not as steep as what we saw in July, but this is a cause of concern.”

Health officials rely on having accurate data to forecast surges in coronavirus cases, hospitalizations, intensive care needs and deaths. California overall has reported steady numbers even as there have been surges in many other states.