A health worker injects an experimental Chinese coronavirus disease (COVID-19) vaccine to volunteer and doctor Naim Celik as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

A health worker injetcs an experimental Chinese coronavirus disease (COVID-19) vaccine to a volunteer as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

Volunteer hospital employee Gurkan Kaya is injected with an experimental Chinese coronavirus disease (COVID-19) vaccine as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

A volunteer is injected with an experimental Chinese coronavirus disease (COVID-19) vaccine as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

A health worker holds an experimental Chinese coronavirus disease (COVID-19) vaccine to inject a volunteer as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

A volunteer is injected with an experimental Chinese coronavirus disease (COVID-19) vaccine as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

A volunteer is injected with an experimental Chinese coronavirus disease (COVID-19) vaccine as Turkey began final Phase III trials at Kocaeli University Research Hospital in Kocaeli, Turkey September, 25, 2020. REUTERS/Murad Sezer

Paramilitary police officers wearing face masks march past a floral installation featuring medical workers, volunteers, scientists and military soldiers in the fight against the coronavirus disease (COVID-19), set up ahead of Chinese National Day on October 1, on Changan Avenue in Beijing, China September 25, 2020. REUTERS/Tingshu Wang

A worker is seen next to a floral installation featuring medical workers, volunteers, scientists and military soldiers in the fight against the coronavirus disease (COVID-19), set up ahead of Chinese National Day on October 1, on Changan Avenue in Beijing, China September 25, 2020. REUTERS/Tingshu Wang

A volunteer is injected with a vaccine as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A health worker takes a blood sample from a volunteer during a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer is injected with a vaccine as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer waits to be injected with a vaccine as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer is injected with a vaccine as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer is injected with a vaccine as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A health worker takes a blood sample from a volunteer during a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A health worker disposes a syringe after taking a blood sample from a volunteer during a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer reacts while a swab sample is taken as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

A volunteer fills a form as he participates in a coronavirus disease (COVID-19) vaccination study at the Research Centers of America, in Hollywood, Florida, U.S., September 24, 2020. REUTERS/Marco Bello

Activist and volunteer, part of the Cannabico Mexican Movement, waters marijuana plants, inside the protest cannabis garden next to Mexico's Senate building during a call for legalization in Mexico City, Mexico September 24, 2020. REUTERS/Carlos Jasso

Activist and volunteer, part of the Cannabico Mexican Movement, plants marijuana plants, inside the protest cannabis garden next to Mexico's Senate building during a call for legalization in Mexico City, Mexico September 24, 2020. REUTERS/Carlos Jasso

Volunteers help students register to vote and request their ballots for the upcoming presidential elections as early voting begins in Ann Arbor, Michigan, U.S., September 24, 2020. REUTERS/Emily Elconin

Volunteers help students register to vote and request their ballots for the upcoming presidential elections as early voting begins in Ann Arbor, Michigan, U.S., September 24, 2020. REUTERS/Emily Elconin

Volunteers help students register to vote and request their ballots for the upcoming presidential elections as early voting begins in Ann Arbor, Michigan, U.S., September 24, 2020. REUTERS/Emily Elconin

Volunteers's hands covered with gloves are seen at a quarantine center, amid the outbreak of the coronavirus disease (COVID-19), in Yangon, Myanmar, September 24, 2020. REUTERS/Shwe Paw Mya Tin

A volunteer is seen at a quarantine center, amid the outbreak of the coronavirus disease (COVID-19), in Yangon, Myanmar, September 24, 2020. REUTERS/Shwe Paw Mya Tin

Volunteers wearing face shield and other protective equipments work at a quarantine center, amid the outbreak of the coronavirus disease (COVID-19), in Yangon, Myanmar, September 24, 2020. REUTERS/Shwe Paw Mya Tin

A volunteer wearing face shield and other protective equipment gestures at a quarantine center, amid the outbreak of the coronavirus disease (COVID-19), in Yangon, Myanmar, September 24, 2020. REUTERS/Shwe Paw Mya Tin

Mr Djibril Mbaye a volunteer, walks in neighbours's flooded courtyard, after heavy rains in Yeumbeul district on the outskirts of Dakar, Senegal September 15, 2020. Picture taken September 15, 2020. REUTERS/Christophe Van Der Perre

Volunteers and Lane County employees unload supplies for the community after a wildfire came through the area in Blue River, Oregon, U.S. September 23, 2020. REUTERS/Jim Urquhart

Volunteers unload supplies for the community after a wildfire came through the area in Blue River, Oregon, U.S. September 23, 2020. REUTERS/Jim Urquhart

Tennis - ATP 500 - Hamburg European Open - Am Rothenbaum, Hamburg, Germany - September 23, 2020 A volunteer is pictured wearing a protective face mask during the Hamburg Open REUTERS/Fabian Bimmer

A volunteer places American flags representing the 200,000 lives lost in the United States in the coronavirus disease (COVID-19) pandemic on the National Mall in Washington, U.S., September 22, 2020. REUTERS/Joshua Roberts

A volunteer places American flags representing some of the 200,000 lives lost in the United States in the coronavirus disease (COVID-19) pandemic on the National Mall in Washington, U.S., September 22, 2020. REUTERS/Joshua Roberts TPX IMAGES OF THE DAY

Britain's Prince Edward and Sophie, Countess of Wessex, and their children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her son James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her son James, Viscount Severn, clean rubbish with volunteers from the Marine Conservation Society and Southsea Beachwatch behind beachgoers during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Prince Edward and his children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Prince Edward and his children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Prince Edward and Sophie, Countess of Wessex, together with their children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Prince Edward and Sophie, Countess of Wessex, together with their children Lady Louise and James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, joins volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her son James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Britain's Sophie, Countess of Wessex, and her son James, Viscount Severn, join volunteers from the Marine Conservation Society and Southsea Beachwatch during the Great British Beach Clean in Southsea, Britain September 20, 2020. REUTERS/Toby Melville/Pool

Residents and volunteers pick up trash along the polluted Baseco coastline of Manila Bay, on International Coastal Cleanup Day, in Manila, Philippines, September 19, 2020. REUTERS/Eloisa Lopez

Government workers and volunteers pick up trash along the Manila Bay shore, during the International Coastal Cleanup Day, in Manila, Philippines, September 19, 2020. REUTERS/Eloisa Lopez

Volunteer Malakai Weller, 8, carries milk donations at the Estacada fire relief station during the aftermath of the Riverside Fire that ravaged Clackamas County in Estacada, Oregon, U.S., September 18, 2020. REUTERS/Shannon Stapleton

Local volunteer Krystyl Nelson carries food donations at the Estacada fire relief station during the aftermath of the Riverside Fire that ravaged Clackamas County in Estacada, Oregon, U.S., September 18, 2020. REUTERS/Shannon Stapleton

Local volunteer Krystyl Nelson carries food donations at the Estacada fire relief station during the aftermath of the Riverside Fire that ravaged Clackamas County in Estacada, Oregon, U.S., September 18, 2020. REUTERS/Shannon Stapleton

A woman volunteer at the Estacada fire relief station carries donations for the community during the aftermath of the Riverside Fire that ravaged Clackamas County in Estacada, Oregon, U.S., September 18, 2020. REUTERS/Shannon Stapleton

A volunteer applies alcohol hand gel to an elderly woman before she makes a PCR test in the Raval district, after Catalonia's regional authorities announced restrictions to contain the spread of the coronavirus disease (COVID-19) in Barcelona Spain September 17, 2020. REUTERS/Nacho Doce

Volunteers carry donations at Bentley Feed store during the aftermath of the Riverside Fire in Molalla, Oregon, U.S., September 16, 2020. Picture taken September 16, 2020. REUTERS/Shannon Stapleton

Darian Zeppetella, 18, a volunteer with the Molalla RFPD Fire Station 82 department, stands during the aftermath of the Riverside Fire in Molalla, Oregon, U.S., September 15, 2020. Picture taken September 15, 2020. REUTERS/Shannon Stapleton

A nurse inoculates a volunteer with Russia's "Sputnik-V" vaccine against the coronavirus disease (COVID-19) in a post-registration trials stage at a clinic in Moscow, Russia September 17, 2020. REUTERS/Tatyana Makeyeva

Community health volunteers check the temperature of a woman at a slum area during a check up campaign for the coronavirus disease (COVID-19) in Mumbai, India, September 16, 2020. REUTERS/Francis Mascarenhas

Community health volunteers check the temperature of a girl at a slum area during a check up campaign for the coronavirus disease (COVID-19) in Mumbai, India, September 16, 2020. REUTERS/Francis Mascarenhas

Britain's Prince William and Catherine, Duchess of Cambridge visit a mosque to meet volunteers, who have supported members during COVID-19 lockdown, in East London, Britain, September 15, 2020. Ian Vogler/Pool via REUTERS