SAN MATEO, Calif. - San Mateo High School students danced, ate and gave each other corsages at their prom this month at the Asian Art Museum.
And then, at least 90 of them also got COVID as of Thursday, according to the district's superintendent.
Masks were strongly recommended at the April 9 prom, according to Supt. Kevin Skelly, but many students did not wear them.
"The District cares deeply about the health and safety of members of our community and creating opportunities for students to enjoy and benefit from student activities such as performing arts, athletics, and senior rites of passage. We have been and will continue to be driven by these values," Skelly said in a statement.
The students who contracted the virus have mild symptoms or are asymptomatic cases.
A total of 600 students were at the prom.
The school district is preparing for Hillsdale High School's prom, which is planned for this week. Masks will be required to attend the indoor event and a negative COVID test.
This COVID outbreak follows on the heels of a similar experience in Marin County where 112 8th graders returned from their field trip to Washington, D.C. on April 9 and two dozen of them immediately tested positive for COVID-19.
That number swelled to at least 56 a few days later, Marin Health & Human Services Dr. Matthew Willis said.
Public health officials said all the infected students in Marin County reported mild or no symptoms and none are hospitalized.
A total of 90% of Marin County 8th graders are fully vaccinated with over half of them having received their booster shot, officials said.
Many people who are vaccinated, especially if they are young and healthy, experience cold-like symptoms with a runny nose and cough for a few to several days.
Despite the surge in cases, overall, the World Health Organization says that the number of reported new COVID-19 cases worldwide decreased by nearly a quarter last week, continuing a decline since the end of March.
The Geneva-based U.N. health agency said in a weekly report that nearly 5.59 million cases were reported between April 11 and 17, 24% fewer than in the previous week. The number of newly reported deaths dropped 21% to 18,215.
The countries with the highest reported case numbers last week were South Korea with more than 972,000, France with over 827,000 and Germany with more than 769,000, WHO said. The highest numbers of new deaths were reported by the U.S., with 3,076, Russia with 1,784 and South Korea with 1,671.
In all, more than 502 million cases of COVID-19 and nearly 6.2 million deaths related to the coronavirus have been reported so far.
The Associated Press contributed to this report.