(NEW YORK) — As hospitals in some areas struggle and ICU beds run short, recent events like bar crawls and family gatherings may have contributed to the increase in coronavirus cases across the country, experts say.

In the middle of May, clusters of tourists flocked to states like South Carolina, Minnesota and Missouri as hotels, bars and attractions in those states reopened.

Over Memorial Day weekend, hundreds of tourists were seen on video and in photographs throughout Missouri’s Lake of the Ozarks, ignoring guidelines that health and government officials had been enforcing since late March.

Weeks later, local health officials in Missouri issued a warning after a person who had visited restaurants and bars during the Memorial Day weekend tested positive for COVID-19. Officials later said a second COVID-19 patient had also gone to the same bars as the first case.

Based on antibody testing, for every case that is diagnosed there may be 10 people infected, Dr. Robert R. Redfield, the director of the Centers for Disease Control and Prevention, said Thursday.

At a surprise birthday party in Texas on May 30, a family member unknowingly interacted with guests while infected with COVID-19.

Now, nearly a month later, 18 family members — including two elderly members and one with breast cancer — have been diagnosed with the virus, according to ABC affiliate WFAA-TV.

“Every activity that involves contact with others has some degree of risk right now,” according to a press release issued by the CDC on Thursday.

Health officials in Minnesota say that out of about 100 of the state’s newest cases, many are residents in their 20s who said they frequented bars on June 12 and 13.

When 12 Kentucky residents went on a weekend getaway to Myrtle Beach, at least nine tested positive for the virus within four days of returning home, according to Louisville ABC affiliate WHAS-TV.

Officials have repeatedly warned residents that even though states are reopening in phases, preventative measures like social distancing, washing hands, disinfecting commonly touched areas and wearing cloth face masks should be heeded if going out in public.

“By taking these steps, you can help protect yourself, your loved ones, and others around you, including those most vulnerable to severe illness,” the CDC said.

The governors of Connecticut, New Jersey and New York are so concerned about spread that they’ve issued a joint travel advisory requiring people coming from states that have a high infection rate to quarantine for 14 days.

The coronavirus was first detected in the U.S. on Jan. 20 in Washington state, and had spread to every state by March 17. To date, there have been more than 2.4 million confirmed cases in the U.S., according to Johns Hopkins University.

Copyright © 2020, ABC Audio. All rights reserved.