UK government wait for Omicron evidence is high stakes | Coronavirus


In a long and difficult cabinet meeting on Monday, hawkish ministers demanded “compelling evidence” that Omicron risked overwhelming the NHS to justify the cost of action, while Boris Johnson on Tuesday confirmed his view that there isn’t enough evidence to justify further action – yet.

While some clarity on the hospitalization rate associated with the new variant should be available within a day or two, scientists have warned that getting the evidence ministers want can be “a difficult task.” So why is it so hard to train and what does it mean for decision making?

Omicron cases are doubling faster than every 48 hours, which means the number of people who will develop serious illness is also increasing exponentially. However, it takes around 10 days from testing positive for Covid for this increase to be seen in hospital data.

Ten days ago, the total number of confirmed cases of Omicron in the UK was 1,898. As of December 19, the cumulative total was 45,145 – although the actual number is several times higher as so many people infected are not tested and there is a delay in confirming suspected Omicron cases. Hospitals in London are reporting an increase in Covid admissions, but in 10 days the number is expected to multiply, no matter how severe Omicron is, due to the large number of infections.

Many scientists remain skeptical of claims that Omicron triggers less severe disease. It is more certain that many of those who have been vaccinated will experience less severe illness, which means that fewer of these people will be admitted to hospital. Yet determining precisely what impact vaccinations – and boosters in particular – will have is fraught with difficulty.

Modeling studies are useful, but they tend to predict a range of scenarios. “You go from something that isn’t as bad as last winter to a lot worse. From a policy-making point of view, this is not very helpful, as they do not attribute any probability to any of these scenarios, ”said Dr Raghib Ali, Senior Clinical Research Associate in the Unit. Epidemiology of the MRC of the University of Cambridge.

“I think the compelling evidence is a difficult question,” said Professor Sheila Bird, formerly of the Biostatistics Unit of the Medical Research Council at the University of Cambridge. “What I imagine [minsters] try to do is work [what] is the effect of booster vaccinations on hospitalization rates for Omicron versus Delta. But it depends on how many people who were boosted about four weeks ago, then had two weeks to develop full protection against this booster, at that point got Omicron vs. Delta, and then were hospitalized.

Part of the problem is that things are constantly changing: The rate at which people have received reminders has changed, while fear of the spread of Omicron has made some people behave more cautiously or look for more PCR tests. large number.

Others said the risk to the NHS and other sectors of society was not so much the severity of the disease as it was the extraordinarily high number of infections. “It’s the transmission that determines the impact more than the severity,” Jeremy Farrer, director of the Wellcome Trust and former Sage member, told the Today program. He said the country has so far been in the most difficult and uncertain time of the pandemic.

Even with high use of booster vaccines, some will remain more vulnerable to serious illness, and not everyone has received a booster or has had time for the booster to work. Then there are about 6 million adults who have not been vaccinated at all. “That’s a lot of people, and the level of transmission is where it is today,” Farrer said.

Uncertainties remain, but Ali believes a clearer picture should emerge imminently. “The key metric, which takes into account both the intrinsic severity of Omicron and the degree of human escape, is the rate of hospitalization of cases – so, for a given number of cases, what proportion ended up in the hospital? ‘hospital ? ” he said. “With Delta, it’s currently around 2%. With Omicron, we don’t know yet, but I would have thought it should happen this week, as there have been enough cases now.

Yet even this estimate will only be a rough estimate, due to the small number of cases and their demographics.

Dr David Pascall, Postdoctoral Research Associate, also in the MRC Biostatistics Unit, said: “Estimates can be made in real time, but early estimates will be imprecise and biased. Accurate and stable estimates can only be generated early next year. Probably in the second half of January.

“At the moment, cases of Omicron have increased the most in younger age groups who are likely to have less negative results on infection. We can expect that this will not last, in particular because of the increased intergenerational diversity expected during the Christmas period. This will have unpredictable impacts, given the remaining questions about the efficacy of vaccine protection against Omicron.

“As such, we may have expectations about the severity of infections during this wave, but compelling evidence of both absolute severity and severity relative to Delta (over the same time period) cannot be generated only after hospitalizations. “

However, worry is not limited to the NHS being overwhelmed. High absence rates in key sectors such as education, law enforcement or food processing and delivery could have unforeseen impacts on our lives in the weeks to come. Dr Simon Clarke, Associate Professor of Cellular Microbiology at the University of Reading, said: “People naturally focus on hospitalizations and deaths, but we must not overlook the effects of mass illness on services. public, infrastructure and economic activity.

And then there’s the long Covid: infections must be minimized to prevent the risk of disability and long-term suffering, experts warn.

Waiting for irrefutable proof is a high stakes bet. The government made a similar bet in March 2020 when it delayed the introduction of measures as other countries locked down. He lost, resulting in months of restrictions, hardship and unnecessary death. The UK is better off now, thanks to vaccines, but Omicron has added an extra dimension of uncertainty. It is by no means that certain ministers will not lose more.

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