Capt. Sir Thomas Moore, the 100-year-old British World War II veteran who garnered global attention for his fundraising efforts amid the pandemic, has died after contracting COVID-19.

His death was announced Tuesday on social media accounts run by his family.

Moore was being treated for pneumonia over the past few weeks. After testing positive for COVID-19 last week, the centenarian was hospitalized on Sunday because "he needed additional help with his breathing," his daughter said in a statement posted on Twitter.

Last spring, Moore raised over 37 million pounds ($50.7 million) for the United Kingdom's National Health Service by walking laps in his garden in England amid a nationwide lockdown. Queen Elizabeth II honored Moore's charity and service to the country with a promotion to honorary colonel, a social flyover and knighthood.

A Buckingham Palace spokesperson told ABC News the queen "is sending a private message of condolence" to Moore's family and that she "very much enjoyed" meeting them last year.

"Her thoughts, and those of the Royal Family, are with them, recognising the inspiration he provided for the whole nation and others across the world," the spokesperson said.

ABC News' Zoe Magee contributed to this report.

Andrew Yang, who ran for president of the United States in 2020 and is currently running to be mayor of New York City, has tested positive for COVID-19.

"After testing negative as recently as this weekend, today I took a COVID rapid test and received a positive result," Yang said in a statement through his campaign Tuesday.

Yang said he has mild symptoms and that, as he self-quarantines at home, he'll "continue to attend as many virtual events as possible."

"Our team has begun the contact tracing process to notify anyone who may have been in close contact with me," he added.

Spanish professional soccer club Real Madrid announced Tuesday that its president has tested positive for COVID-19.

Florentino Perez, 73, returned a positive result during the Madrid-based club's routine testing. He is not showing any symptoms, the club said in a brief statement.

No additional details were provided by the club.

Results from a late-stage clinical trial of Russia's flagship coronavirus vaccine show the shot is not only safe but also 91.6% effective against symptomatic COVID-19, according to a study published Tuesday by the peer-reviewed medical journal The Lancet.

The randomized, double-blinded, placebo-controlled Phase 3 trial in Moscow involved 19,866 adult participants, of whom 14,964 received the vaccine, called Sputnik V, and 4,902 received a placebo. The two-dose vaccine was administered 21 days apart.

There were 62 confirmed cases of COVID-19 identified among the trial participants in the placebo group and 16 cases in the vaccine group, according to the study.

The study said there were no serious adverse effects related to the vaccine recorded during the trial and that 94% were mild, including flu-like symptoms, pain at the injection site and headaches.

A sub-analysis of 2,144 trial participants older than 60 showed the vaccine had a similar efficacy of 91.8%, according to the study.

"Our interim analysis of this phase 3 trial of Gam-COVID-Vac has shown promising results," the researchers wrote.

The publication of peer-reviewed data follows last year's criticism of Russia for registering the COVID-19 vaccine -- and declaring itself the first country in the world to do so -- before starting crucial Phase 3 trials.

"The development of the Sputnik V vaccine has been criticised for unseemly haste, corner cutting, and an absence of transparency," Ian Jones, a professor of virology at England's University of Reading, wrote in a comment piece published Tuesday by The Lancet alongside the study. "But the outcome reported here is clear and the scientific principle of vaccination is demonstrated, which means another vaccine can now join the fight to reduce the incidence of COVID-19."

Russia’s Direct Investment Fund (RDF), which funded the production of Sputnik V and is responsible for its worldwide marketing, hailed the study and noted that the COVID-19 vaccine is currently one of only three in the world with an efficacy above 90%. The vaccine, which is now registered in 16 countries, costs $10 per dose and can be stored and transported more easily because it can be kept at the temperature of a standard refrigerator, according to RDF.

"The data published by The Lancet proves that not only Sputnik V is the world’s first registered vaccine, but also one of the best," Kirill Dmitriev, CEO of RDF, said in a statement Tuesday.

ABC News' Patrick Reevell contributed to this report.

Dr. Stephen Hoge, president of American biotechnolgy company Moderna, said he's hopeful that vaccines can help the U.S. population achieve herd immunity against the novel coronavirus by mid-year.

"It really depends what you think herd immunity needs to be. But if you assume 50 to 70% of the population, then we're working hard ourselves and the other manufacturers to make sure that's a possibility really in the late spring, early summer," Hoge told ABC News chief anchor George Stephanopoulos in an interview Monday on "Good Morning America."

"It's ultimately going to depend upon the delivery of those vaccines, and so that's something that the states and the health care providers in this country are ultimately leading the way on as well as Americans deciding they want to receive that vaccine," he added. But we're optimistic that by the middle of the year, we'll be able to achieve those sorts of numbers."

Moderna is ramping up production of its COVID-19 vaccine and is working to clear any "bottlenecks" in the supply chain, according to Hoge.

"At this point, a lot of the logistical bottlenecks that we're running into are problems we can solve on our own," he noted. "We're in good shape."

Hoge, who was a resident physician in New York City, said data currently shows that existing vaccines are still effective against all emerging strains of the virus. But the variant first identified in South Africa "is of some concern because it looks like it could hide from the vaccine a little better than others," he said.

"So our approach in Moderna is going to be to develop a booster vaccine so that if the South African variant or any other variant becomes a concern, we'll be able to offer a way to identify that, prevent it from hiding from the vaccine," he said.