(CNN) -- When Brittany Hall from upstate New York received her first Covid-19 vaccine after barely leaving home since last March, she pulled out her phone and took a selfie to mark the occasion. "I cried so hard the lady that helped me had to comfort me," she said in a tweet along with the picture. "I can't wait to hug my dad and my nieces."

 If you're still scrambling to find a COVID-19 vaccine appointment, a mass vaccination event in a rural Missouri county still has slots open Saturday.

More states are relaxing measures to protect against COVID-19 as variants circulate in the United States -- a combination that means "we're walking into the mouth of the monster," an infectious disease expert said.

The pace of Covid-19 vaccine administration in the US continues to improve, each day bringing the country closer to herd immunity -- the point at which enough people are protected against a disease that it cannot spread.

Four elderly sisters in New Jersey haven't been able to have their regular get-togethers during the coronavirus pandemic, but they made an exception to get their Covid-19 vaccinations.