Omicron wave seems to have peaked in South Africa, London next?

In a matter of weeks, the omicron Covid-19 variant — first detected in South Africa and Botswana in November — has surged around the world, leading to millions of new cases and the re-imposition of coronavirus restrictions in many countries.

The U.S. and Europe have been rolling out booster shots as fast as they can following research findings by Covid vaccine makers Pfizer-BioNTech and Moderna that the omicron variant undermines the effectiveness of the standard two doses of their Covid shots, but that booster shots significantly increase the level of protection against the variant.

Nonetheless, cases in both regions have soared, with the U.S. reporting over 1 million new daily Covid cases on Monday, and the U.K. and France also among those reporting staggering numbers of daily infections, upward of 200,000 a day in recent tallies. Hospitalizations are also steadily rising in affected countries, although admissions and deaths remain far below previous peaks.

As well as an increasing body of evidence suggesting that omicron causes less serious disease than its predecessors, experts are cautiously optimistic that while the omicron wave is proving to be sharper than those associated with previous variants, it could also be shorter.

South Africa believes its omicron wave has peaked, for example, and London — where omicron cases surged in December before the variant really took hold in the rest of Europe — may be seeing cases starting to plateau, according to experts, fueling hope that the omicron wave could soon peak elsewhere too.

South Africa’s government issued a statement on Dec. 30 in which it said that the country’s Department of Health had reported a 29.7% decrease in the number of new cases detected in the week ending Dec. 25 (89,781 cases), compared with the number of new cases detected in the previous week (127,753). 

“All indicators suggest the country may have passed the peak of the fourth wave at a national level,” the statement said, with cases declining in all provinces except the Western Cape and Eastern Cape, which recorded increases of 14% and 18%, respectively.

Nonetheless, there has been a decline in hospital admissions in all provinces except the Western Cape, the statement added, noting that admissions had been generally lower with the omicron variant.

“While the omicron variant is highly transmissible, there has been lower rates of hospitalisation than in previous waves. This means that the country has a spare capacity for admission of patients even for routine health services. There is a marginal increase in the number of deaths in all the provinces.” 

Global experts have been watching South Africa’s Covid data closely, as it was among the first countries to detect the omicron variant and to alert the World Health Organization, which designated the heavily mutated strain a “variant of concern” on Nov. 26.

Real-world studies from South Africa and the U.K. suggest that people infected with omicron develop milder illness compared with the previously globally dominant delta variant. Omicron is far more transmissible, however, meaning that a larger number of cases could translate into more pressure on health services.

When omicron was first detected by doctors in South Africa, they observed that their patients appeared to be experiencing milder illnesses more akin to a cold than the flu, symptoms of which were associated with earlier strains of Covid. South African doctors also found that most people hospitalized with omicron had been admitted to hospital for other reasons and did not require oxygen.

Another study published in the International Journal of Infectious Diseases on Dec. 28 suggested that the omicron wave of hospital admissions in Tshwane (a city in South Africa’s Gauteng province where omicron cases surged in December) had peaked “within 4 weeks of its commencement. Hospital admissions increased rapidly and began to decline within a period of 33 days.”

Fareed Abdullah, director of AIDS and tuberculosis research for the South African Medical Research Council, likened the omicron wave of infections to a “flash flood” and described the speed of the omicron wave’s rise, peak and decline as “staggering.”

Like South Africa, the U.K. has been watched closely as it was the first European country to be hit hard by a surge in omicron infections in December, before the variant spread in the U.S. and in mainland Europe.

The U.K.’s capital London saw omicron infections soar in December but there are signs that cases are starting to plateau, again suggesting that this omicron wave will peak faster than previous ones.

Epidemiologist Neil Ferguson, a professor from the School of Public Health at Imperial College London, commented Tuesday that he is “cautiously optimistic that infection rates in London in that key 18-50 age group, which has been driving the omicron epidemic, may possibly have plateaued,” although he told the BBC’s “Today” radio show that “it’s too early to say whether they’re going down yet.”

“We may see a different pattern in hospitalizations,” he noted, echoing other public officials who have warned that U.K. hospitals are likely to come under further stress in the coming weeks, with Ferguson noting that “we may see high levels for some weeks.”

Hospitalizations and deaths tend to lag new infections by several weeks, but the U.K.’s widespread Covid vaccination program has helped to keep admissions to hospital and deaths far lower than in the initial stages of the pandemic. Whether South Africa’s omicron experience can be compared with the U.K. remains to be seen, given the difference in demographics, vaccine coverage and immunity levels among the populations.

Lawrence Young, professor of molecular oncology at Warwick University, told CNBC on Tuesday that “it does look as though cases are plateauing in London in the 18-50 age group” but that the next few weeks will prove crucial in seeing how the omicron crisis plays out.

“The issue now is spread to older age groups which is likely to have been fuelled by mixing over the holiday season and will lead to more severe outcomes and hospitalisations,” he noted, as well as “more infection in younger school-age children [that] will further increase case numbers.”

“But given the widespread and rapid spread of omicron along with the level of immunity in the population, there won’t be many susceptible people left to infect so case numbers are expected to fall over the next couple of weeks. This may not resemble the same sharp fall as has been reported in South Africa due to different rates of infection in different parts of the U.K. influenced by variable restriction measures,” he noted.

Danny Altmann, professor of immunology at Imperial College London, told CNBC on Tuesday that South Africa’s omicron data and experience are a cause for optimism, as is the fact that Europe’s “massive caseload” of omicron infections “isn’t proportionally translating into enhanced intensive care unit admissions and deaths, notwithstanding the caveat that it takes time to die.”

Hospital admissions were the key metric to watch, according to Professor David Heymann, an epidemiologist at the London School of Hygiene and Tropical Medicine.

“This coronavirus, like other coronaviruses, will be an endemic virus in humans and eventually will likely cause a common cold. That’s because as the immunity within the population increases, and already the antibody levels in the U.K. are over 90%, once that occurs the virus is modified — it isn’t prevented from reinfecting or from infecting people who have been vaccinated — but it is being prevented from causing serious illness and that’s why watching hospital admissions is extremely important,” he told CNBC’s “Squawk Box Europe” Wednesday.