Ellen Prosser, known as Nell, who is 100 years old, receives the Oxford/AstraZeneca COVID-19 vaccine from Dr Nikki Kanani at the Sunrise Care Home, amid the coronavirus disease (COVID-19) pandemic in Sidcup, Britain January 7, 2021. Kirsty O'Connor/Pool via REUTERS TPX IMAGES OF THE DAY REFILE - CORRECTING YEAR

A resident at Hamilton Park Nursing and Rehabilitation, a nursing home facility, receives the coronavirus disease (COVID-19) vaccine from Walgreens Pharmacists in Brooklyn, New York, U.S., January 4, 2020.

Donald Caster, 88, receives the coronavirus disease (COVID-19) vaccine at Mission Commons assisted living community in Redlands, California, U.S., January 15, 2021.

A elderly woman receives a booster shot of her vaccination against the coronavirus disease (COVID-19) at an assisted living facility, in Netanya, Israel January 19, 2021.

Jello shots in syringes are handed out to residents after they received the coronavirus disease (COVID-19) vaccine at the Brightwater Senior Living community in Highland, California, U.S., January 22, 2021.

Seniors, who are 65 and over, wait in line at the Department of Health Sarasota COVID-19 vaccination clinic in Sarasota, Florida, U.S. January 4, 2021.

A healthcare worker of Asl Roma 1 gets ready before starting vaccinations at the Villa Verde elderly care home in Rome, as part of the coronavirus vaccination campaign in Italy, January 7, 2021.

A soldier assists an elderly woman as she arrives to receive a dose of the coronavirus disease vaccine at the New York State COVID-19 vaccination site at the Jacob K. Javits Convention Center, in New York City, U.S., January 15, 2021.

William Mattox, 89, is offered a glass of champagne after receiving the coronavirus disease (COVID-19) vaccine at the Brightwater Senior Living community in Highland, California, U.S., January 22, 2021.

An elderly woman gestures after receiving a vaccine against the coronavirus disease (COVID-19) at a nursing home in Athens, Greece, January 4, 2021. Louisa Gouliamaki/Pool via REUTERS

A resident receives a dose of the Pfizer-BioNTech COVID-19 vaccine at the Villa Verde elderly care home, as part of the coronavirus vaccination campaign in Rome, Italy, January 7, 2021.

Doreen Vickers, 83, waits as a health worker fills a syringe with a dose of the Oxford/AstraZeneca COVID-19 vaccine at the Appleton Village Pharmacy, amid the coronavirus disease (COVID-19) outbreak, in Widnes, Britain January 14, 2021.

Betty Nelson, 81, who got in line at 6am, reads on her tablet while waiting for a coronavirus disease (COVID-19) vaccine clinic run by the Jamestown S'Klallam Tribe to open in Sequim, Washington, U.S. January 23, 2021. The tribe, which is sharing its excess vaccines with Sequim residents, was able to begin the first-come, first-served site earlier than other locations in the state due to its tribal sovereignty.

Marcie Meek, 88, poses for a photo with a sign referring to herd immunity after receiving the coronavirus disease (COVID-19) vaccine at the Brightwater Senior Living community in Highland, California, U.S., January 22, 2021.

Pat Fischer, 94, talks to Marguerite Crockem before receiving the coronavirus disease (COVID-19) vaccine at the Brightwater Senior Living community in Highland, California, U.S., January 22, 2021.

A medical worker administers a dose of the Pfizer-BioNTech Covid-19 vaccine to patient Blandine Johannel at the EPHAD (care home and day centre for elderly people) of the hospital in Vannes, as part of the coronavirus disease (COVID-19) vaccination campaign in France, January 7, 2021.

A resident of a nursing home holds the hand of a staff worker before receiving a vaccine against the coronavirus disease (COVID-19) in Athens, Greece, January 13, 2021.

Residents of an assisted living facility dance after receiving their booster shots of the vaccination against the coronavirus disease (COVID-19), in Netanya, Israel January 19, 2021.

Elderly, over 75 years of age, register to receive the Pfizer-BioNTech COVID-19 vaccine at a coronavirus disease vaccination center in Lamballe-Armor, France, January 22, 2021.

Elderly people wait at the newly opened coronavirus disease (COVID-19) vaccination center at the Messe Berlin trade fair grounds in Berlin, Germany January 18, 2021. Sean Gallup/Pool via REUTERS

A resident is seen before she receives a dose of the Pfizer-BioNTech Covid-19 vaccine at the EHPAD (care home and day centre for elderly people) operated by DomusVi in Asnieres-sur-Seine, as the spread of the coronavirus disease (COVID-19) continues in France, January 8, 2021.

Pianist Ove Nyvik entertains elderly residents as they wait to receive a coronavirus disease (COVID-19) vaccine at the Rotnes church, in Nittedal, Norway January 21, 2021. Stian Lysberg Solum/NTB via REUTERS

Residents are seen before they receive a dose of the Pfizer-BioNTech Covid-19 vaccine at the EHPAD (care home and day centre for elderly people) operated by DomusVi in Asnieres-sur-Seine, as the spread of the coronavirus disease (COVID-19) continues in France, January 8, 2021.

An elderly woman claps her hands after receiving a vaccine against the coronavirus disease (COVID-19) at a nursing home in Athens, Greece, January 4, 2021. Louisa Gouliamaki/Pool via REUTERS

A elderly woman receives a booster shot of her vaccination against the coronavirus disease (COVID-19) at an assisted living facility, in Netanya, Israel January 19, 2021.

An elderly people, over 75 years of age, receives a dose of the Pfizer-BioNTech COVID-19 vaccine at a coronavirus disease vaccination center in Lamballe-Armor, France, January 22, 2021.