UK provides clues as to how Omicron could play in the US


LONDON — The UK is emerging as a testing ground in the battle for dominance between the new Omicron variant of the coronavirus and Delta, the earlier strain that is currently the cause of most infections in the US- United and Europe.

How Britain Behaves Against Omicron will offer clues to the United States and the rest of the industrialized world about how the variant behaves in a highly vaccinated population, how sick people get and whether its dozens of mutations have given Omicron a sufficient edge on the scalable scale to deprive Delta of the hosts it needs to stay on top.

South Africa alerted the world to Omicron in late November and is seeing a rapid rise in infections with the new variant.

But scientists say it may not be a reliable model for what could happen with Omicron in the US and Europe, as it has lower vaccine coverage, a younger population, and the variant is not. not compete with a lot of Delta cases. It’s summer in the southern hemisphere too, and the virus tends to spread more easily when people are clustered indoors in the winter. Many South African cases have been mild.

New hospitalization data published in South Africa has indicated that Omicron causes a milder infection than previous variants, even though it spreads faster.

Michelle Groome, who heads the public health division of the South African National Institute of Communicable Diseases, told a press conference on Friday that researchers found a disconnect between infections and hospitalizations compared to previous strains , with fewer hospitalizations among those infected and a slight increase in the number of deaths. She warned that the results could be due to the limited sample size at the start of the wave.

The UK is more like the US and will likely be a better guide to how Omicron plays out – and not for the first time, having been hit by the Alpha variant earlier than North America. Its population is older than that of South Africa, vaccination coverage is widespread and, since an almost complete reopening in the summer, it has experienced a sustained but manageable period of Delta cases, hospital admissions and death. It also has a sophisticated surveillance system to monitor variants, and its doctors and scientists are posting tons of data and analysis on Covid-19.

Scientists and vaccine makers are studying Omicron, a variant of Covid-19 with around 50 mutations, which has been detected in many countries after spreading to southern Africa. Here’s what we know as the United States and others enforce travel restrictions. Photo: Fazry Ismail / EPA-EFE / Shutterstock

Now, with more confirmed cases than the US or anywhere in Europe, the UK is facing Omicron. Prime Minister Boris Johnson reimposed some public health restrictions in England this week in a bid to stem the spread of the new variant, as public health officials warned Omicron was set to cause a million infections in Britain by the end of the month. Omicron cases are doubling every two or three days, public health officials say, pointing to the variant’s potential to displace Delta as the more common variant within weeks.

Still, there are unanswered questions about the extent of Omicron’s transmission advantage over Delta, and to what extent it can evade immunity conferred by a previous infection or vaccination. Another pressing question is whether vaccination will protect people against serious illnesses. Delta could prove difficult to dislodge. The unfolding of the Omicron wave in the UK should provide some answers, scientists say. Omicron has been detected in 23 US states, according to the Centers for Disease Control and Prevention.

Omicron samples in Elandsdoorn, South Africa.


Jérôme Delay / Associate Press

“It is impossible to understand what is going on here without knowing what is going on in the UK, South Africa and other places where the variant has appeared,” said Philip Landrigan, director of the Health Program. global public and the common good. at Boston College.

Confirmed cases of Omicron in the UK totaled 1,265 on Friday, up from 448 the day before. Health Secretary Sajid Javid said this week that the true number of infections could be closer to 10,000 and the variant is rapidly gaining ground.

Scientists on a panel advising the government said on Wednesday that without certain restrictions, Omicron hospital admissions could reach 1,000 per day by the end of the year if the variant continues to spread to its current pace. This would add to the number of admissions caused by Delta. The seven-day average of new Covid-19 cases in the UK was 49,200 on Friday – a weekly rate of over 500 per 100,000 people – and hospitalizations are around 790 per day.

The panel sketched out six scenarios for how the Omicron phase of the pandemic could play out.

The first three, which the modelers advising the government say are the most likely, are that Omicron has a transmission advantage over Delta and may partially evade immunity conferred by vaccination or a previous infection. , thereby expanding the pool of people who may be infected. These advantages mean that Omicron would ultimately outperform Delta, just as Delta would push back earlier variants such as the Alpha.

A Covid-19 testing clinic in London.


Stephen Chung / Zuma Press

“The only way one infection leads another to extinction is when they compete for the same resources – sensitive people,” said Matt Keeling, director of the Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research at the University of Warwick.

The difference between the three scenarios is the severity of the situation in terms of the number of infected people who need to be hospitalized. While scientists are optimistic that vaccines will continue to protect most people against serious illness with Omicron, the grim prognosis is that even though the number of admissions linked to each Omicron case is lower than that of Delta, The other benefits of the variant mean the scale of the epidemic could still lead to an upsurge in serious illness, stretching the capacity of the state-run national health service to cope. A greater severity of the disease would mean a more deadly wave.

“Omicron made the road a little colder”

– Graham Medley, Professor of Infectious Disease Modeling at the London School of Hygiene and Tropical Medicine

In an effort to slow Omicron, Mr Johnson on Wednesday asked the British to work from home where possible, wear masks in indoor public spaces and prepare to show proof of vaccination or a Covid-19 test negative to enter nightclubs and other places.

The remaining scenarios, according to the panel, are less likely. In one, Omicron does not have a greater ability than Delta to circumvent immunity, but has a transmission advantage. That would mean it would eventually displace Delta, but Britain’s immunity bulwark is keeping the outbreak in check.

In another, Omicron turns out to be less dangerous than expected due to continued exposure to Delta, which was not as prevalent in South Africa when the new variant appeared, bolsters protection against Omicron. The last possibility is that Delta will stay on top and Omicron will break out sporadically during small outbreaks. This happened with the Beta variant, which also spread quickly in South Africa but never established itself in Britain or the United States.


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Evidence from laboratory studies suggests that booster shots should improve people’s protection against Omicron. The UK has given boosters to nearly 22 million people, or one-third of its population, and the government has expanded those eligible to anyone over 18 and shortened the interval between second doses and reminders at three months.

Graham Medley, professor of infectious disease modeling at the London School of Hygiene and Tropical Medicine and co-chair of the panel’s modeling group, compared the last phase of the pandemic to driving a car. Vaccines, booster shots, and precautions such as wearing masks act as seat belts and safety checks, reducing a person’s risk of being injured in an accident.

“Omicron made the road a little bit colder,” he said.

Corrections and amplifications
An earlier version of this article said the UK coronavirus case rate was nearly 500 per 100,000 people, without specifying that this was a weekly rather than a daily figure. With an update based on data from Friday, the weekly case rate now exceeds 500 per 100,000 people. (Corrected December 10, 2021)

Write to Jason Douglas at [email protected]

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