US president-elect Joe Biden has received his first dose of the coronavirus vaccine on live television as part of a growing effort to convince the American public the inoculations are safe.
He took a dose of Pfizer vaccine at a hospital not far from his Delaware home, hours after his wife, Jill Biden, did the same.
The injections came the same day that a second vaccine, produced by Moderna, will start arriving in states.
It joins Pfizer's in the nation's arsenal against the COVID-19 pandemic, which has now killed more than 317,000 people in the United States and upended life around the globe.
"I'm ready," said Biden, who was administered the dose at a hospital in Newark, Delaware, and declined the option to count to three before the needle was inserted into his left arm.
"I'm doing this to demonstrate that people should be prepared when it's available to take the vaccine. There's nothing to worry about."
The president-elect praised the health care workers and said President Donald Trump's administration "deserves some credit getting this off the ground."
And Biden urged Americans to wear masks during the upcoming Christmas holiday and not travel unless necessary.
Other top government officials last week joined the first wave of Americans to be inoculated against COVID-19 as part of the largest largest vaccination campaign in the nation's history.
Vice President Mike Pence, House Speaker Nancy Pelosi, Senate Majority Leader Mitch McConnell, and other politicians were given doses on Friday.
They chose to publicise their injections as part of a campaign to convince Americans that the vaccines are safe and effective amid skepticism, especially among Republicans.
Vice president-elect Kamala Harris and her husband are expected to receive their first shots next week.
But missing from the action has been President Donald Trump, who has spent the last week largely out of sight as he continues to stew about his election loss and floats increasingly outlandish schemes to try to remain in power.
It's an approach that has bewildered some top aides who see his silence as a missed opportunity for the president, who leaves office January 20, to claim credit for helping oversee the speedy development of the vaccine and to burnish his legacy.
Trump, who in the past has spread misinformation about vaccine risks, has not said when he intends to get the shot.
He tweeted earlier this month that he was "not scheduled" to take it, but said he looked "forward to doing so at the appropriate time."
The White House has said he is still discussing timing with his doctors.
Trump was hospitalised with COVID-19 in October and given an experimental monoclonal antibody treatment that he credited for his swift recovery.
A Centers for Disease Control and Prevention advisory board has said people who received that treatment should wait at least 90 days to be vaccinated to avoid any potential interference.