More megasites are being added to places for COVID-10 vaccinations.

More COVID vaccine megasites open nationwide, including at Yankee Stadium More than 36 million vaccine shots currently on the market have been administered nationwide, and 7.5 million people are now fully vaccinated. YahooNews

More COVID-19 vaccination megasites opened this week across the country, including at a casino in Missouri and at Yankee Stadium in New York — where a long line formed as it opened on Friday to local residents.

Legendary MLB player Mariano Rivera was there, encouraging people to get their shots. "Now, it's time to support you and let you know that it's okay to be vaccinated," Rivera said.

More sites are on the way. In California, Levi's Stadium in Santa Clara County will become the state's biggest vaccination site when it opens early next week, according to the county and the San Francisco 49ers. The goal is to be able to vaccinate as many as 15,000 people there a day.

The news came after NFL commissioner Roger Goodell told President Joe Biden in a letter dated Thursday that the league is making all of its 32 stadiums available as vaccination sites for the general public, Michael George reported for "CBS This Morning: Saturday."