U.S. officials, meanwhile, pointed to growing evidence that the illness caused by the fast-spreading Omicron variant is less severe than that of previous strains of the virus as hospitalizations continued to lag behind a record surge of new infections.
In a briefing at the White House on Wednesday, Centers for Disease Control and Prevention Director Rochelle Walensky said that while caseloads have rocketed, hospitalizations and deaths have remained comparatively low. Anthony Fauci, the Biden administration’s chief medical adviser, said all indications point to Omicron being less severe than the Delta variant and that vaccine booster shots will be critical to the U.S.’s approach to tackling the rise in infections.
“We must remember that hospitalizations and deaths are lagging indicators,” he said. “However, the pattern and disparity between cases and hospitalization strongly suggest that there will be a lower hospitalization-to-case ratio when the situation becomes clear.”
Mr. Fauci also said that a second booster shot might be needed to top up immunity levels, but there isn’t enough data yet to determine the durability of the protection provided by the current round of boosters.
Covid-19 cases in the U.S. have continued to climb, setting a fresh pandemic record on Wednesday of 300,887 cases a day on a seven-day average, according to a Wall Street Journal analysis of Johns Hopkins University data.
The post-Christmas surge in cases has pushed the seven-day average past its previous peak of 251,989 set on Jan. 11, 2021, although there was less testing during the earlier stages of the pandemic.
As of Wednesday, the seven-day average of hospitalizations for confirmed and suspected Covid-19 was 77,840, according to data from the U.S. Department of Health and Human Services. That is an increase of about 14% over the past two weeks.
The seven-day average of hospitalizations, though increasing, is below both the pandemic peak of 137,510 on Jan. 10, 2021, and the smaller peak of 102,967 on Sept. 4, 2021, during the Delta surge.
Other countries, including France and the U.K., have also seen hospitalizations lag behind record-high numbers of new infections in recent days, prompting some to reassess self-isolation periods for people infected or exposed to the virus to minimize the disruption to healthcare and other critical sectors. Employee absences due to infection from the Omicron variant led to thousands of flight cancellations over the Christmas weekend, while officials in the U.S. and elsewhere have expressed concern over how quarantines are affecting hospital staffing levels.
The WHO, though, on Wednesday said there is a risk that some people will go on to develop and spread the disease after shorter quarantine periods expire. “So it is a trade-off between the science and being absolutely perfect in what you try to do, but then having the minimal disruption that you can possibly have to your economy and society,” said Michael Ryan, the WHO’s emergencies director. “And governments are struggling to find that balance.”
Spain on Wednesday said it would reduce the quarantine period for people who have tested positive for Covid-19 to seven days from 10 as infections surged to record highs. Italy said it would abandon self-isolation requirements for those coming into contact with people testing positive, provided they have been vaccinated or have recently recovered from infection.
The CDC this week advised that infected people who are asymptomatic can leave isolation after five days and should wear masks when around other people for another five days; those who are vaccinated and exposed to someone with Covid-19 should wear a mask for 10 days and try to get tested five days after exposure.
In South Africa, where the Omicron variant was first detected, data from the National Institute for Communicable Diseases said average daily hospital admissions in Gauteng province, which includes Johannesburg, fell by more than 20% in the two weeks to Dec. 25 compared with the two weeks before. On a weekly basis, average daily admissions were down nearly 40% with declines also recorded in other provinces.
Two doses of Johnson & Johnson’s Covid-19 vaccine reduced hospitalizations from the Omicron variant by up to 85%, another South African study found. The paper, which hasn’t been peer reviewed, indicated that there was a significant increase in protection in the weeks and months after receiving a booster—an important finding as many African nations are depending on the J&J vaccine for their immunization campaigns.
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