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As the heavily mutated Omicron variant rips across South Africa at an astonishing rate — likely because it’s better at causing reinfections and breakthrough cases than any previous version of the coronavirus — anxious observers in the U.S. and elsewhere have been reassured this week by some better-than-expected news.
First, as the New York Times noted Tuesday, “there are early indications that Omicron may cause less serious illness than other forms of the virus,” including a report from researchers at a major hospital complex in Pretoria, South Africa, about how COVID-19 patients there “are much less sick than those they have treated before,” as well as supporting testimony from “other hospitals [that] are seeing the same trends.”
Omicron “almost certainly is not more severe than Delta,” Dr. Anthony Fauci, America’s top infectious disease expert, predicted Tuesday — and “there is some suggestion that it might even be less severe.” Centers for Disease Control and Prevention Director Rochelle Walensky confirmed Wednesday that “the disease is mild” in almost all U.S. cases seen so far.
Then on Tuesday and Wednesday, multiple teams of scientists released preliminary findings from the first studies designed to assess how well Omicron dodges immunity acquired through infection or vaccination.
As anticipated, they discovered a significant degree of evasion in blood samples taken from people relying solely on two vaccine shots or “natural immunity” to shield them from infection. Fortunately, the antibody response in those who had either received a booster shot or been vaccinated and infected was much stronger.
“Three doses against Omicron are almost equivalent to the two doses’ effectiveness we had against the original variant,” Albert Bourla, Pfizer’s chairman and chief executive, said in a televised interview.
The studies also seemed to confirm that the immune system’s T-cells and B-cells — which learn how to stave off severe illness in the future after an initial encounter with the virus or the vaccine — will help immunized and/or recovered individuals retain a high level of protection against hospitalization and death.
But while all of this is cause for hope, it shouldn’t be cause for complacency.
“When you hear, ‘Omicron, no big deal, because this is a mild disease,’ understand that for some, that is true — but not for all,” explained Ashish K. Jha, the dean of the Brown University School of Public Health. “That's why [it’s] critical to get first and second shots for as many unvaccinated as quickly as possible and third shots for everyone else.”
As Jha went on to note, people with boosters or hybrid immunity seem like they could be sufficiently protected from Omicron — and most people with two shots or prior infection may avoid its worst consequences.
But a variant that infects even vaccinated and recovered people as rapidly and readily as Omicron doesn't need to boast “a great degree of severity” or completely evade vaccines to inflict a great degree of damage.
It just needs to keep spreading until it reaches the vast number of people worldwide who are still susceptible to hospitalization and death.
“A small share [severe illness] of a rapidly increasing number [all infections] can still become a big number — and [infection] numbers are going up very, very fast,” John Burn-Murdoch, a data journalist at Financial Times, has pointed out. “This is why Omicron remains worth taking very, very seriously in South Africa, in Europe, in the U.S. and elsewhere.”
Experts like Fauci aren’t wrong when they describe the hospitalization data out of South Africa as “encouraging.” The latest numbers from South Africa’s National Institute for Communicable Diseases show that in the Gauteng province — the epicenter of the Omicron outbreak — the share of COVID-positive patients in the ICU or on ventilators is two to three times lower than it was at the same stage of the country’s Delta wave, suggesting “a reduction in severity of outcomes,” according to Burn-Murdoch.
Omicron patients also appear to be spending less time in the hospital — another sign of “milder illness.”
This data substantiates preliminary reports from COVID doctors in Pretoria and elsewhere that “the majority of patients in the COVID wards have not been oxygen dependent” and that this wave has been marked by a “much shorter average length of stay.”
So far, so good — particularly in a country where 13 percent of residents live with HIV (which nearly doubles the risk dying of COVID) and where only about a third are fully vaccinated. In comparison, 60 percent of Americans are fully vaccinated and just 0.4 percent are living with HIV.
But the big question about milder illness in South Africa is why. So far, both cases and hospitalizations have been “skew[ing] *much* younger” during the country’s new Omicron wave than they were at the start of its recent Delta surge, and younger people always tend to get less sick from COVID-19. In South Africa, most have already been exposed to earlier versions of the virus as well, acquiring at least some immunity against severe illness.
So if the reason for the relative mildness of South Africa’s current caseload is that virus itself has evolved to become inherently less virulent — that is, less likely to trigger severe disease in anyone who gets infected — then the same pattern will play out worldwide, and Omicron will end up being less dangerous than Delta.
Yet if the reason Omicron seems to be producing milder illness right now in South Africa has less to do with the virus itself than with whom it’s infecting — that is, disproportionately younger South Africans whose immune systems have been primed by past exposure to COVID-19 — then there’s no certainty that older, more vulnerable individuals will fare as well when they inevitably encounter the new variant.
“Does Omicron lead to less severe illness than prior variants? We don't [know] yet,” Dr. Eric Topol, director of the Scripps Research Translational Institute, cautioned Tuesday. “That's an uncertainty that will remain until we see much larger numbers of people age 60+ without immunity” getting infected.
And the problem is that many of them will get infected with Omicron.
By Wednesday, South Africa detected 19,842 new COVID-19 cases — a 131 percent increase from one week ago and the largest daily total since July. Nearly 27 percent of tests are coming back positive. Scientists there have said the new variant appears to spread more than twice as quickly as Delta — and that at least part of the reason is because the risk of reinfection with Omicron is roughly 2.4 times higher than with the original version of the virus, according to their estimates.
Initially, higher vaccine uptake among South Africans over 60 appeared to be part of the reason why Omicron infections were skewing so young. But now cases seem to be spreading to older groups as well, and ICU admissions and ventilator use in the epicenter of the outbreak may be rising as a result.
Meanwhile, Denmark reported Tuesday that Omicron has spread “society-wide.” And on Wednesday Britain’s Health Security Agency released new data suggesting “that Omicron is displaying a significant growth advantage over Delta” and will likely to outcompete the earlier variant to become dominant in the UK.
“It is increasingly evident that Omicron is highly infectious and there is emerging laboratory and early clinical evidence to suggest that both vaccine-acquired and naturally acquired immunity against infection is reduced for this variant,” Susan Hopkins, the chief medical adviser to the agency, said in a statement. “It is therefore absolutely critical that we all do everything that we can to help break the chains of transmission and slow the spread of this new variant.”
In the U.S., 60 percent of the population is fully vaccinated, but only 14.5 percent of Americans have been boosted. Right now, Delta — a much less evasive variant — is causing more than 120,000 cases and nearly 1,300 deaths per day as mitigation measures lapse and the country moves closer and closer to normalcy. What will happen if and when Omicron takes over?
“I still think Omicron is highly problematic,” Florian Kammer, a leading virologist at Mount Sinai’s Icahn School of Medicine, tweeted Tuesday. “If it spreads widely — and the signs are that it will do that — we will likely see another wave. The wave may be less severe in terms of [the] number of deaths because many people will have partial immunity. But as we see now with the Delta wave, even in relatively highly vaccinated populations the virus finds those who are vulnerable (because of medical conditions or because they chose to stay unvaccinated) and does a lot of damage. And currently the vaccination rate in the US is pretty low. My speculation is that this variant will significantly prolong the pandemic.”
Despite progress on vaccination and widespread exposure to earlier variants, millions of people in the U.S. — and far more elsewhere — remain at risk for severe COVID-19. Omicron is so new that it hasn’t had time to infect many of them. In the weeks ahead, it will do everything in its power to change that.