U.K. running high-stakes, real-world vaccine experiment

It is putting vaccines to the test amid one of the world's worst coronavirus outbreaks, propelled by a variant of the virus that is more contagious and possibly more deadly than the original.

Britain is ahead of most countries in the vaccination race, but it is gambling that it can extend the interval between two doses to stretch limited supplies.

And while those vaccinations are underway, Britain is trying to determine how rigid and long a lockdown may be necessary to inhibit the virus as it has evolved. The variant now dominant here has been found in at least 50 other countries, including the United States.

So, pay attention, world. The findings that emerge from here in the coming weeks and months will have critical implications for you, too.

As of Monday, almost 6.6 million people in the United Kingdom had gotten the first of two doses of a coronavirus vaccine - either Pfizer-BioNTech or the homegrown Oxford-AstraZeneca jab - and another 470,000 have gotten the second booster shot, according to the government's daily summary. That's more inoculations per capita than the United States or any country in Europe. (Moderna is authorized here, too, but it will not arrive until March).

At the same time, Britain is fast approaching 100,000 dead, and on many days it records the highest per capita death toll from covid-19, the illness the novel coronavirus can cause, on the planet as it desperately tries to keep its hospitals from being overwhelmed.

Prime Minister Boris Johnson said at a Tuesday evening news briefing: "I'm deeply sorry for every life that has been lost, and, of course, as prime minister, I take full responsibility for everything the government has done. What I can tell you is that we truly did everything we could and continue to do everything that we can."

The entire country is now in its third week of its third national lockdown, with no idea when strict stay-home orders and school closures will be eased - and by how much.

April may be overly optimistic, scientists warn.

Yet even as it struggles, Britain remains a scientific powerhouse, with some of the best infectious-disease surveillance and modeling in the world, coupled with a cutting-edge consortium tracking the emergence of new variants. It also has a well-run national health-care system, which is collecting reams of data available to researchers.

British scientists reasonably expect to be among the first to answer some of the big outstanding questions of the pandemic: How well do vaccines, shown to be safe and effective in clinical trials, work in the real world? Do they save lives? Lessen disease? Block transmission? Will vaccines alone be enough to end lockdowns?

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Britain's vaccination campaign began on Dec. 8, and scientists say they should soon be able to begin to measure how well at least the first jabs are protecting the population.

Early results from Israel, which is also moving quickly to vaccinate, suggests that a first dose of the Pfizer-BioNTech vaccine reduced positive tests for coronavirus by a third.

The vaccination rollout in Britain has gone smoothly despite the government's failure to launch a "world-beating" test-and-trace program and its stumbles getting personal protective equipment into hospitals in the early days of the pandemic.

Britain's vaccinations are now taking place at more than 1,300 sites, including hospitals, doctors' offices, pharmacies, horse racing courses, town halls, cathedrals, arenas, a shuttered cinema and a mosque.

Experts say that while there have been problems - London Mayor Sadiq Khan complained that the hard-hit capital has not gotten its fair share of doses yet - the country has been able to scale up quickly, in part because of its centralized, top-down National Health Service system.

"If you tell 30,000 GP doctors to do something, they will do it, and you can make it happen relatively quickly," said Nigel Edwards, chief executive of the Nuffield Trust, a London-based health think tank.

Officials aim by mid-February to have given a first round to 15 million people, including nursing home residents and caregivers, front-line health-care workers, those with other illnesses that put them at extreme risk, and everyone 70 and above.

But to get a shot to as many people as possible, the government is delaying second doses - administering boosters up to 12 weeks out, rather than the recommended three to four weeks.

AstraZeneca's trials included some doses scheduled as far as 12 weeks apart. Pfizer, though, has warned that it does not have evidence to support such a long delay, and the British Medical Association on Sunday said the second doses of the Pfizer vaccine should be delayed no more than six weeks.

Other countries are watching the British experiment, hoping success here will mean they, too, can spread available doses further while waiting for additional shipments.

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Pfizer and Moderna have said laboratory testing showed that their vaccines would be effective against the virus variant that has emerged in Britain. But researchers caution that the hopeful results must be seen in the real world.

The variant, first detected in London and southeastern England, may be 30% to 70% more transmissible, having evolved to bind more tightly to human cells, easing entry and replication, virologists have found. It may also be more deadly.

"It's really a serious turn for the worse, unfortunately," said John Edmunds, a professor of disease modeling at the London School of Hygiene & Tropical Medicine.

England's chief scientific adviser, Patrick Vallance, said that among 1,000 men age 60 or older who get infected, the original virus would kill 10. The new variant, he said, would kill 13 or 14 - an increase of at least 30%.

Understanding of the variant is still in its early stages. Preliminary research suggesting that it might spread more effectively in children than the original virus is being reexamined. But the early data sets, examining the fates of 50,000 patients here, appear robust, said Edmunds, who led one of the studies that prompted a government announcement about higher mortality on Friday.

Because the variant appears to spread more easily through the population, it leads to more infections, which send more people to the hospital, where more of them might die.

Edmunds said the variant appears to be more lethal. He and other disease modelers said they were careful to screen out other possible causes for higher mortality, such as how busy a hospital might be.

The scientists said they must await larger data sets to see whether younger people also face higher mortalities.

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Prime Minister Boris Johnson ordered a third national lockdown on Jan. 4, after it was clear that regional restrictions were not sufficient to contain the spread of the variant.

People are supposed to stay in their homes except in special circumstances. Mixing between households is banned. Schools are closed, as are all but essential shops.

Three weeks in, the lockdown has begun to reduce the increase in new infections, even as the numbers of hospitalizations and deaths continue to soar.

There is growing pressure on Johnson to lift restrictions as soon as possible. But British health experts warn that getting through this wave of infections, especially against new variants, may be much harder, and take much more time, than previous spikes.

They advise that even with a mass vaccine rollout, mask use, social distancing and other restrictions should continue through spring and into the summer. They caution that some measures may need to be kept in place until the fall, when Britain promises to have all adults vaccinated.

Matt Keeling, a modeler at the University of Warwick and member of the government's science advisory team, said there is 100 times more virus circulating now than in the summer, making more people more vulnerable, despite the deployment of vaccines.

"Vaccines are not a panacea," said Keeling, who added that scientists still do not know how protective the jabs will be after the first and second doses and whether the vaccines can stop the chains of transmission.

Mark Woolhouse, a professor of infectious-disease epidemiology at University of Edinburgh, who also advises the British government, said a quick release from lockdown in April could lead to "a huge wave of infections."

Woolhouse said that if even 90% of Britain's 10 million most vulnerable people receive an effective vaccine, that would leave 1 million without immunity.

Researchers assume that as more and more people are protected against the virus by immune responses generated by vaccines or past infections, herd immunity will begin to offer some respite by blocking the virus's ability to move from person to person freely.

When that threshold will be reached for the coronavirus is unknown.