The White House’s possible “superspreader” reception at the Rose Garden, held on Sept. 26 for Supreme Court Justice nominee Amy Coney Barrett, may have caused over 10 attendees to test positive for COVID-19, including the president and first lady.

Superspreading events occur when one person transmits the virus to several other individuals. The virus typically spreads from person-to-person in close contact, according to the Center for Disease Control and Prevention. Before going to the reception, attendees had to get tested and receive a negative result, according to The New York Times. However, it can take days for the test to detect the virus.

Some attendees that have tested positive include President Donald Trump, First Lady Melania Trump, former advisor Kellyanne Conway, Senator Mike Lee, Senator Thom Tillis and Notre Dame President John Jenkins. Barrett previously had coronavirus, but tested negative before the reception.

It has not been officially confirmed that the Rose Garden event caused the spread. However, over 100 people came to the event — many photographed without masks and in close proximity to one another. 

On Saturday, former Governor of New Jersey, Chris Christie, revealed he also tested positive for COVID-19. He, among a few other advisors like Bill Stepien and Kellyanne Conway, prepared President Trump behind closed doors for the first presidential debate in Cleveland on Sept. 29. He also attended the Rose Garden reception at the White House for Barrett.

The news of three Republican senators testing positive for COVID-19 may affect Barrett’s nomination to the Supreme Court. The Senate Judiciary Committee still plans to convene on Oct. 12 to advance the confirmation process. However, in the Senate, Republicans have a 53–47 majority. Two Republican party members already oppose Barrett’s nomination — if Sen. Johnson, Sen. Lee and Sen. Tillis are absent, Republicans may not have the votes necessary to successfully push through the nomination.

Much uncertainty remains regarding how many others at the Rose Garden event contracted COVID-19. White House officials said they would have immense difficulty tracing who the virus spread to given the number of people present at the time.