Virginia Gov. Ralph Northam gives a thumbs up after he receives a COVID-19 vaccination from Lt. Col. Kris Clark, of the Virginia Air National Guard at the Governor's Mansion in Richmond, Va., Monday, March 15, 2021. Northam got a shot of the Johnson & Johnson coronavirus vaccine on Monday, joining the growing number of Virginians who are being inoculated against the potentially deadly disease. (AP Photo/Steve Helber)

Canada's Prime Minister Justin Trudeau tours a COVID-19 vaccination clinic in Montreal on Monday, March 15, 2021. (Paul Chiasson/The Canadian Press via AP)

People wearing face masks to protect against the spread of the coronavirus visit at Yasukuni shrine in Tokyo, Monday, March 15, 2021. (AP Photo/Koji Sasahara)

Canada's Prime Minister Justin Trudeau watches as a COVID-19 vaccine is prepared while he tours a vaccination clinic in Montreal, on Monday, March 15, 2021. (Paul Chiasson/The Canadian Press via AP)

Residents line up to wait at a vaccination site set up in the Marseille soccer Velodrome stadium, during a presentation to the media, in Marseille, Monday, March 15, 2021. The government plans to inoculate 10 million citizens by mid-April, 20 million by mid-May and a total of 30 million, or two-thirds of the adults by summer. (AP Photo/Daniel Cole)

Robert Post, of Wallingford, enters Masonicare Health Center with wife Eileen to visit his mother Pearl Post, 87, at the assisted living community in Wallingford, Wednesday, March 10, 2021. Masonicare Health Center opened to visitors Wednesday afternoon. (Dave Zajac/Record-Journal via AP)

A woman disinfects the handrails of the main dock gangway on Alcatraz Island in San Francisco, Monday, March 15, 2021. The historic island prison was reopened to visitors Monday after being closed since December because of the coronavirus threat. Visitors were also able to tour the inside of the main cell house for the first time in a year. (AP Photo/Eric Risberg)

Vehicles are lined up bumper to bumper on Fern Street from Somerton Avenue to Union Avenue early Monday, March 15, 2021 during Sunset Health's mass vaccination program for farmworkers at Joe Munoz Park. (Randy Hoeft/Yuma Sun via AP)

First lady Jill Biden deplanes at the McGuire Air Force Base, Monday, March 15, 2021, in Burlington, N.J. The first lady is part of a Biden administration cross-country tour this week to highlight the benefits of the $1.9 trillion coronavirus relief plan. (Anna Moneymaker/Pool via AP)

People wearing face masks to curb the spread of COVID-19, sit at distance in a tram in downtown Rome, Monday, March 15, 2021. Half of Italy's regions have gone into the strictest form of lockdown in a bid to curb the latest spike in coronavirus infections that have brought COVID-19 hospital admissions beyond manageable thresholds.(AP Photo/Alessandra Tarantino)

A box of AstraZeneca vaccine is pictured in a pharmacy in Boulogne Billancourt, outside Paris, Monday, March 15, 2021. Germany, France and Italy on Monday became the latest countries to suspend use of AstraZeneca's COVID-19 vaccine over reports of dangerous blood clots in some recipients. (AP Photo/Christophe Ena)

Nurse Sara Muela, left, administers the Johnson & Johnson COVID-19 vaccine to educator Rebecca Titus at a vaccination site setup for teachers and school staff at the Berks County Intermediate Unit in Reading, Pa., Monday, March 15, 2021. (AP Photo/Matt Rourke)

Pierre Cohen, left, receives Pfizer's COVID-19 vaccine at a vaccination site set up in the Marseille soccer Velodrome stadium, during a presentation to the media, in Marseille, Monday, March 15, 2021. The government plans to inoculate 10 million citizens by mid-April, 20 million by mid-May and a total of 30 million, or two-thirds of the adults by summer. (AP Photo/Daniel Cole)

A nun wearing a face mask to curb the spread of COVID-19, walks past a closed shop in downtown Rome, Monday, March 15, 2021. Half of Italy's regions have gone into the strictest form of lockdown in a bid to curb the latest spike in coronavirus infections that have brought COVID-19 hospital admissions beyond manageable thresholds. (AP Photo/Alessandra Tarantino)

Residents of different nursing homes take their first excursion outside their care homes after been vaccinated, with the skyline of Madrid in the background in Madrid, Spain, Monday, March 15, 2021. The group are now fully protected from the deadly COVID-19 virus having received their vaccination a few weeks ago. The care home managers thought that it was time for them to enjoy a trip into central Madrid to take in the sights and stretch their legs. (AP Photo/Manu Fernandez)

A resident of a nursing home takes her first excursion outside her care home with other residents after being vaccinated, in Madrid, Spain, Monday, March 15, 2021. The group are now fully protected from the deadly COVID-19 virus having received their vaccination a few weeks ago. The care home managers thought that it was time for them to enjoy a trip into central Madrid to take in the sights and stretch their legs. (AP Photo/Manu Fernandez)