After a superspreader concert and gatherings throughout the holiday season, a surge of COVID-19 infections overwhelmed Puerto Rico despite a successful vaccination campaign in the U.S. territory.

Following a Bad Bunny concert of about 60,000 people, roughly 2,000 people contracted the virus. The concert as well as business events, company holiday parties and family get-togethers contributed to a 4,600 percent increase in cases in Puerto Rico, according to The New York Times.

“We did so well; we followed the rules,” 53-year-old Laura Delgado, who was at the concert, told the Times. “We followed the mask mandate. Our vaccination rate was so high that we let our guard down. The second Christmas came, we were like, ‘We’re going to party!’”

As the island grapples with issues such as government bankruptcy and a departure of many health care professionals, officials implemented more restrictions on travelers and diners in an effort to curb the spread of COVID-19, the newspaper added.

But Harvard University statistician Rafael Irizarry tweeted that one-third of Puerto Rico’s COVID-19 cases throughout the entirety of the pandemic occurred in the last month. Also in December, hospitalizations on the island doubled twice, according to the Times.

The Coronavirus Resource Center at Johns Hopkins University reported a record high testing positivity rate of more than 20 percent and 47,008 new cases in the past week.

Overall, 74.45 percent of Puerto Rico’s population is vaccinated.