What can the world learn from countries where Omicron is surging?

In South Africa, meanwhile, researchers say early data suggests Omicron causes milder symptoms — but it’s still unclear how much of a role immunity from vaccination or previous infection plays.

Denmark is mulling new restrictions in an attempt to control a spike of new cases.

It’s too late to keep Omicron out

Despite many nations imposing a slew of travel restrictions, the variant has spread quickly around the globe.

Records fall and borders close as world races to get control of Omicron

World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus told a news briefing Tuesday that 77 countries have now reported cases of Omicron, and “the reality is that Omicron is probably in most countries, even if it hasn’t been detected yet.”

“Omicron is spreading at a rate we have not seen with any previous variant,” Tedros said. “We’re concerned that people are dismissing Omicron as mild. Surely, we have learned by now that we underestimate this virus at our peril.”

He added that even if Omicron does cause milder disease, “the sheer number of cases could once again overwhelm unprepared health systems.”

The UK government removed 11 countries, all in southern Africa, from its “red list” on Tuesday in light of the spread of the Omicron variant within its own borders, meaning hotel quarantine is no longer required for visitors from those destinations.

The variant has already been detected in at least 40 US states, in addition to Washington DC and Puerto Rico, according to public statements from hospital systems and state officials in their respective states.

“I imagine Omicron will be everywhere soon,” Michael Head, a senior research fellow in global health at England’s University of Southampton, told CNN. “And there’ll be a lot of Omicron around that most countries haven’t detected yet, in part because testing systems and genomic capacities may be limited.”

It may not take long for Omicron to become the dominant strain

The first two cases of the Omicron variant were detected in the UK on November 27. By Tuesday, it had overtaken Delta as the dominant Covid-19 strain in London, according to the UK Health Security Agency.

Omicron is coming but boosters should fight it, US federal health officials say

“Now, more than ever, getting your first, second dose or booster as soon as possible is vital. Please don’t leave it to chance,” London’s regional director for public health Kevin Fenton tweeted.

UK Health Secretary Sajid Javid said Tuesday that Omicron cases were doubling around every two days in the country, adding that “the growth in Omicron cases here in the UK is now mirroring the rapid increase that we are seeing in South Africa.”

On Friday, the UK had reported 93,045 new coronavirus cases, according to government data — the highest daily number since the pandemic began. South Africa also recorded its highest ever number of daily cases Wednesday.

Denmark’s Statens Serum Institute (SSI) said Omicron was expected to become the dominant coronavirus variant this week. Almost 10,000 cases of infection were confirmed in the country in the last 24 hours, the SSI said Thursday.

Danish Prime Minister Mette Fredricksen said that cases were “very, very high” and that she had “no doubt that new measures will be needed to break the chains of infection.”

People line up for booster shots outside a vaccination center at London's St. Thomas Hospital on December 15, 2021.

Meanwhile, the head of the EU Commission, Ursula von der Leyen, told lawmakers in Brussels that the Omicron coronavirus variant was set to become the dominant variant in the 27-nation bloc by mid-January.

In its latest risk assessment, published Wednesday, the European Centre for Disease Prevention and Control (ECDC) warned that there was a “very high” risk that the variant would spread further in the region, adding that it “is considered very likely to cause additional hospitalizations and fatalities,” beyond those already forecast from the Delta variant.

In the United States, National Institute of Allergy and Infectious Diseases Director Dr. Anthony Fauci told CNN Tuesday that Omicron would become the dominant coronavirus variant in the country “for sure” given its doubling time.

But, Fauci said, it’s not yet clear what that will mean for levels of severe disease.

On its website, the US Centers for Disease Control and Prevention now estimates that Omicron makes up 2.9{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of circulating virus, versus Delta’s 96.8{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809}, as of the week ending December 11.

Too early to know if Omicron infection is milder

Data from South Africa is being scrutinized for clues as to how Omicron’s spread could play out elsewhere.

Studies add to evidence Omicron sneaks past vaccines but may cause milder disease

South Africa’s National Institute for Communicable Diseases (NICD) has struck a cautiously optimistic tone. “Although the data are still being gathered, the evidence suggests that the current wave may be milder,” the agency said.

A study released Tuesday by Discovery Health — a large health insurance company in South Africa covering 3.7 million people — found that vaccines provide less protection against the new strain, but gave indications that Omicron causes milder symptoms than previous variants.

Two doses of the Pfizer vaccine were 33{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} protective against infection overall but 70{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} effective in preventing severe complications, including hospitalization, the researchers said.

Meanwhile, the risk of ending up in the hospital from Covid-19 was 29{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} lower for Omicron infections in adults, compared with the original strain, the study estimated.

A resident registers her details at a Covid-19 mobile testing site in the Milnerton district of Cape Town, South Africa, on December 2.

But others are less confident. England’s Chief Medical Officer Chris Whitty warned that UK daily Covid-19 case records “will be broken a lot over the next few weeks as the rates continue to go up,” and that this will translate into “big numbers” needing hospital treatment in the coming weeks.

“I want to be clear: I’m afraid this is going to be a problem,” Whitty said Wednesday. “(The) exact proportions of it, of course, South African scientists and UK scientists and scientists globally are trying to determine at the moment.”

More real-time data is urgently needed before scientists can start to evaluate the severity of Omicron infection in other populations, Head said.

In the UK, scientists will be looking at the impact of the variant on a population where 89{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of the population aged 12 and over has received at least one dose of a Covid-19 vaccine, and 44{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of those aged 12 and over have had two doses and a booster, according to government figures. But the picture is very different elsewhere.

“In a lot of countries around the world there will be people who are unvaccinated or with one dose; across sub-Saharan Africa most people have not yet had two doses,” Head said. “So we need to look a little bit about whether there’s any protection, some protection … in those populations too.”

In South Africa, it’s possible that people already have some immunity to the virus — either through vaccination, previous infection or both — and that’s protecting them, according to Richard Friedland, CEO of the private hospital network Netcare. Multiple studies have shown that people who are naturally infected and then vaccinated have very strong immunity. South Africa’s population is also generally younger.

Vaccinations alone won’t slow Omicron

Health experts recommend that as Omicron spreads, countries continue to deploy the non-pharmaceutical interventions (NPIs) that are already known to reduce transmission of airborne viruses, such as social distancing and improved ventilation indoors.

Why Europe's fight against the pandemic is about to get much more dangerous

“Countries can and must prevent the spread of Omicron with measures that work today,” said Tedros, the WHO chief. “It’s not vaccines instead of masks. It’s not vaccines instead of distancing. It’s not vaccines instead of ventilation or hand hygiene. Do it all. Do it consistently. Do it well.”

Faced with what Prime Minister Boris Johnson described as an incoming “tidal wave” of Omicron infections, the UK government decided to “turbocharge” its campaign to administer booster jabs.

Johnson’s office cited data suggesting that “vaccine efficacy against symptomatic infection is substantially reduced against Omicron with just two doses, but a third dose boosts protection back up to over 70{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809}.”

However, the UK Parliament also approved the introduction of Covid passes, that show proof of vaccination or a recent negative Covid test, for entry to nightclubs and large venues, despite a major rebellion within Johnson’s own party. Lawmakers also passed measures including mandatory mask-wearing in most indoor spaces.

South Africa’s Minister of Health Joe Phaahla called Thursday for “responsible behavior and stronger compliance” with Covid-19 restrictions to prevent a possible surge of cases linked to the holiday season, a ministry news release said.

Head said it was important to continue mitigation measures while ensuring that populations around the world, including poorer nations, get access to three doses of Covid-19 vaccines as fast as possible — which could still take another 12 to 24 months, he cautioned.

Demand for vaccines and testing may rise

The rise of the Omicron variant may encourage more people to get a booster — and cause a spike in demand for Covid-19 tests.

As the UK threw open its booster program this week to all eligible adults, the NHS (National Health Service) website crashed due to demand for booster appointments, lateral flow test kits were no longer available online and long lines formed at vaccination walk-in centers. The UK Health Security Agency said Wednesday it was doubling the number of home testing kits it was sending out.

Denmark’s SSI also reported Tuesday that the country’s Covid-19 testing system was under pressure as infection rates rise.

Demand for vaccines in South Africa has not jumped since Omicron emerged. But South African President Cyril Ramaphosa, who tested positive for Covid-19 on Sunday, has urged his fellow citizens to get the shot. “Do everything you can and need to, to stay safe, beginning with vaccination,” he tweeted. Ramaphosa has been forced to delay his booster shot, his office said.

Despite surging cases, we may not see more lockdowns

There has been little talk of new lockdowns so far, despite concern over the rapid spread of Omicron.

Speaking during a visit to a vaccination center in Ramsgate, southern England, the UK Prime Minister said that rather than “locking stuff down,” the government is asking people to “be cautious” and “think about their activities in the run-up to Christmas.”

Johnson, who has faced a scandal over alleged Downing Street office parties in breach of restrictions last winter, added: “This is very different from last year because what we have is the additional protection of the vaccines and the ability to test.”

How South African scientists discovered Omicron and set off a global chain reaction

“I think scientifically at the minute there is a very strong argument for more interventions in place, but politically that’s less acceptable,” said Head.

However, countries “should be realistic that they may need lockdowns at some point,” he said — whether with this variant or a future one — as a lockdown “is a useful tool of last resort.”

Countries are still drawing on a range of other measures to try to curb the spread of the Omicron and Delta variants. For example, France announced Friday that big outdoor events and gatherings will be banned on New Year’s Eve as the country faces its fifth wave of Covid-19 infections. In Ireland, restaurants and bars will be placed under a 8 p.m. curfew from Sunday. Meanwhile, Norway has placed a ban on serving alcohol in restaurants and bars, in addition to imposing more restrictions in schools and speeding up its vaccination campaign.

But there also appears to be some degree of acceptance that people will have to learn to “live with” the new variant, especially where Covid-19 vaccination rates are high.

In Australia’s New South Wales state — where 93.3{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of people aged 16 and over have been fully vaccinated — restrictions are being eased this week despite Omicron cases being detected.

“The virus is here, Omicron is in Australia and we are going to live with the virus and not let it drag us back,” Australian Prime Minister Scott Morrison told 4BC radio.

CNN’s Naomi Thomas, Virginia Langmaid, Maggie Fox, Niamh Kennedy, Vasco Cotovio, James Frater, Allegra Goodwin and Caitlin McGee contributed to this report.