The World Health Organization warned on Wednesday that the ongoing circulation of the Delta variant and the emergence and rapid spread of Omicron could create a “tsunami” of infections that could overwhelm health systems, even as top US health officials stressed that early data showed Omicron infections gives milder disease.
The global average of new cases hit a new high of more than 930,000 on Tuesday, according to a New York Times database. The previous high was more than 827,000, reaching the end of April.
“Delta and Omicron are now twin threats, driving cases up to record numbers, leading to increases in hospitalization and deaths,” said Dr. Tedros Adhanom Ghebreyesus, Director-General of the WHO, at a press conference in Geneva. “I am very concerned that Omicron, which is highly transferable and spreading at the same time as Delta, is leading to a tsunami of cases.”
But along with the warnings, U.S. officials and the leading scientists at the UN agency said the early data from places where Omicron was spreading gave some cautiously positive signs.
Dr. Rochelle P. Walensky, director of the Centers for Disease Control and Prevention, told a White House news conference that although cases had increased by about 60 percent over the past week, to about 240,000 registered cases each day, hospitalizations and deaths suggested a milder wave of the virus.
“Although our cases have increased significantly from last week, hospital admissions and deaths remain relatively low right now,” she said, pointing to a seven-day average of 9,000 admissions a day, an increase of about 14 percent from last week. The seven-day average of daily deaths was about 1,100 a day, she added, a drop of about 7 percent.
“This may be due to the fact that hospitalizations tend to lag behind in cases of about two weeks,” she said, “but may also be due to early indications that we have seen from other countries such as South Africa and the UK – have milder disease from Omicron, especially among those vaccinated and boosted. “
Referring to a number of international studies showing milder Omicron results, Dr. Anthony S. Fauci, President Biden’s chief medical adviser, said at the same press conference that “the pattern and difference between cases and admissions strongly suggest that there will be a lower admissions to case situation as the situation becomes clearer.”
Dr. Soumya Swaminathan, the scientific director of the WHO, said that early real-world data indicated that the link between infection rates and hospitalizations had been “disconnected”.
She warned that the evidence on Omicron is just emerging. “We still can not predict what this virus will do,” she said.
As it became more and more clear that vaccinated people were being infected with Omicron, meaning that there was a reduction in the vaccines’ capacity to neutralize the virus, the early evidence of the protection that vaccination could provide was positive.
Vaccines, she said, “still seemed to be protective” against serious illness and death. But it was a complicated equation that had to take into account a host of factors – including the clinical vulnerability of those who became infected – and there was simply not enough data.
Dr. Mike Ryan, head of the WHO’s emergency program, said Omicron had not yet worked its way into all sections of society – including the most vulnerable populations and the unvaccinated.
Omicron outbreaks around the world, he said, started primarily in younger age groups, and the variant is only now moving into older population groups.
“I think we will still see decoupling from cases and serious illness,” he said. But the large number of daily cases – the “power of infection” – can lead to increases in patients and increased pressure on health systems.
He also noted that even in countries with abundant vaccines, there were large pockets of unvaccinated people, and it was simply too early to know whether Omicron itself is less virulent than the variants that have come before.
Dr. Tedros said that “the narrative going on right now that it is milder or less serious” could be dangerous, as the high transmission rates alone could lead to an increase in hospitalizations and deaths.
“We should not undermine the bad news with the good news,” he said. “There are both elements here.”