DALLAS >> Jill Biden played offense today in the fight against COVID-19, teaming up with an NFL Hall of Fame running back to encourage Texans to get vaccinated against the disease.

“Today, we are finally getting back the things that we lost. But as far as we’ve come, we’re not done yet,” the first lady said in brief remarks after she toured a pop-up vaccination clinic at Emmett J. Conrad High School.

She was accompanied by former Dallas Cowboys running back Emmitt Smith, who used a sports metaphor to make the same point.

“We’re in the fourth quarter, and the game is far from over,” Smith said after the tour as they addressed a group of people who had just been vaccinated.

The first lady flew to Texas as part of President Joe Biden’s campaign to vaccinate as many Americans as possible against COVID-19 in the face of growing concern about the spread of a new and more contagious strain of the coronavirus known as the delta variant.

Biden had set a goal of vaccinating 70% of adult Americans by Sunday’s July Fourth holiday, when he plans a White House celebration of the nation’s independence from the virus.

But while the administration has acknowledged it will fail to meet the president’s goal, the White House has said the president, first lady, vice president and her husband will continue to barnstorm the country encouraging holdouts to roll up their sleeves.

Nationwide, 66% of adults have received at least one dose of a COVID-19 vaccine, according to the Centers for Disease Control and Prevention.

In Texas, just under 50% of people ages 12 and older — the demographic being served at the Dallas high school’s clinic — have been fully protected against the disease caused by the coronavirus, according to state COVID-19 data on the CDC’s website.

“It’s just not enough, which is why I wanted to come here today,” Jill Biden said, stressing that the vaccines in use are safe, effective and free.

The Dallas clinic is open to students 12 years and older, school staff, parents and anyone from the broader Dallas community. The Dallas Independent School District is hosting community vaccine clinics at different high schools daily this week.

Parkland Health & Hospital System is administering the Pfizer vaccine, which requires two doses administered three weeks apart.

As an incentive, anyone getting vaccinated at the high school will receive tickets to the Six Flags Over Texas theme park. They will also be eligible to win prizes, such as airline or concert tickets and gift cards, through a raffle sponsored by Mayor Eric Johnson’s office.

The first lady planned a similar stop later Tuesday in Houston, where she was to pair up with Doug Emhoff, the spouse of Vice President Kamala Harris, to visit a COVID-19 vaccination clinic hosted by the Houston Astros at Minute Maid Park, their home ballpark.

The stop in Houston will be the first joint appearance of the administration for Biden and Emhoff, the second gentleman. They campaigned together several times during the 2020 general election.

The Astros are hosting the clinic as part of Major League Baseball’s “Vaccinate at the Plate” program, held during June, which offers incentives to fans who get protected against COVID-19.