LONDON – The UK’s disclosure on Friday that a new variant of the virus could be more deadly than the original caused a stir over why such alarming information was released when the evidence was so inconclusive. However, its effects are little discussed: it has silenced those who have called for life to return to normal soon.

The UK government is expected to announce in the coming days that it will extend and tighten the nationwide lockdown imposed by Prime Minister Boris Johnson this month. Schools can remain closed until Easter, while overseas travelers may need to be quarantined in hotels for 10 days.

For Mr Johnson, who has faced relentless pressure from members of his own Conservative Party to relax restrictions, the warning of the variant made a strong case that Britain may be in the middle of a serious new phase of the pandemic – and that it does relaxed constraints now could be disastrous.

While scientists agree that the evidence of the variant’s greater lethality is tentative, inconclusive, and based on limited data, they said it was nonetheless served the government’s purposes in the lockdown debate that Mr Johnson, who spoke between Science and politics have often been drawn to have shown an aversion to tough steps.

“It is strange to make such an announcement, which has dire consequences and clearly affects the general public, without a full dataset and more thorough analysis,” said Lawrence Young, a virologist at Warwick Medical School. “I wonder if it was about reiterating the harsh message that the lockdown must be adhered to and increased border controls justified.”

Devi Sridhar, director of the global public health program at the University of Edinburgh, said, “These preliminary data show why waiver restrictions should be applied carefully and measuredly.”

The interests of scientists and government officials have not always been balanced in Britain’s fight against the pandemic. Tensions have increased when Mr Johnson reopened the economy as scientists warned of new infections.

During his briefing on Downing Street on Friday, Mr Johnson, as some noted, had no choice but to confirm concerns that the new variant beating Britain could not only be more contagious but also more deadly. Hours earlier, a well-known epidemiologist, Neil Ferguson of Imperial College London, told a television journalist Robert Peston that a government scientific committee had concluded that there was a “realistic possibility” that the variant could be 30 percent more deadly than it is the original version of the coronavirus.

The Prime Minister’s initial announcement that the variant could be linked to higher death rates contained few details and did not make it clear how uncertain many experts were about the data. While government scientists later published a summary of studies setting out the possible effects of the variant, the number of deaths they analyzed was small and uncertainties about the data resulted in a wide range of estimates.

“We haven’t seen the evidence, which in itself is worrying,” said David King, a former chief scientific advisor to the government who was critical of Mr Johnson’s handling of the pandemic. “I would have simply welcomed the science with a preprint report.”

Dr. Ferguson himself has become something of a lightning rod during the pandemic. In March last year, his models predicted that the uncontrolled spread of the virus in the UK could cause up to 510,000 deaths. These numbers stunned Mr. Johnson and prompted him to impose the country’s first lockdown despite waiting a week to act.

At the time, some scientists criticized Dr. Ferguson on the grounds that he was too public and that his projections were exaggerated. They accused him of publishing inflated projections of death during previous epidemics. After pressing for repression, he was referred to by the British tabloids as “Professor Lockdown”.

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Jan. 26, 2021, 4:31 p.m. ET

Dr. Ferguson later resigned from the government’s Emergency Scientific Advisory Group (SAGE) after admitting he breached lockdown rules by inviting a woman to his home.

As a member of a key SAGE committee, the Advisory Group on New and Emerging Respiratory Virus Threats, which released a report on the lethality of the variant on Friday evening, Dr. Ferguson played a leading role in alerting the new variant. And with the UK death toll nearing 100,000, its projections don’t look all that fantastic even after multiple lockdowns.

Government scientists defended the decision to publish the results in the interests of transparency. The disclosure reflected the rapidly changing thinking of infectious disease experts about the potential of mutations to change the path of the virus. Variants that were discovered earlier in the pandemic received little public attention.

Still, virologists said they were concerned about the lack of a strong theory about how or why the variant, first discovered in the UK, could lead to more people dying. Among other concerns about the new data – the small number of deaths on which the results were based, and the fact that harrowing conditions in hospitals themselves could lead to higher death rates – was the uncertainty about why this could be more dangerous waiting for more dates you said.

“You can see some mechanism by which the transmission rate would be a little higher,” said Ian Jones, professor of virology at the University of Reading. “But why that should lead to a higher death rate is not so easy to see.”

Mutations in the new variant make it easier to attach to human cells, which makes them even more contagious. Virologists said that the same trait could theoretically allow more cells to be infected than older variants, which could lead to wider infection, which in turn could produce a more aggressive and potentially dangerous immune response.

With no laboratory data to suggest this could happen, scientists said it was far too early to understand the models that point to higher death rates.

Even the most reputable methods of studying the effects of the variant yielded a wide range of additional risk estimates, ranging from having virtually no effect on mortality to increasing the risk of death by 65 percent.

Nonetheless, the fact that so many models evaluated by government scientists suggested higher mortality rates has alarmed scientists.

“For now, overall, I’d say it’s likely valid,” said Paul Hunter, professor of medicine at the University of East Anglia. “I can’t believe that all of these different groups would have drawn the same conclusions and made the same mistakes in controlling possible biases. But it’s not beyond the possibilities. “

Even so, scientists said the new variant would not only reinforce the government’s case for restrictions not yet relaxing, but would also require the same policy measures as previous versions of the virus.

“What more can we do just because we know this is more deadly?” Professor Hunter said. “The answer is probably nothing.”