Most Vaccines Unlikely to Prevent Infection from Omicron, Studies Show

A growing body of preliminary research suggests that the Covid-19 vaccines used in most of the world offer almost no defense against becoming infected by the highly contagious Omicron variant.

All vaccines approved in the United States and European Union still seem to provide a significant degree of protection against serious illness from Omicron, which is the most crucial goal. But only the Pfizer and Moderna shots, when reinforced by a booster, appear to have success at stopping infections, and these vaccines are unavailable in most of the world.

The other shots — including those from AstraZeneca, Johnson & Johnson and vaccines manufactured in China and Russia — do little to nothing to stop the spread of Omicron, early research shows. And because most countries have built their inoculation programs around these vaccines, the gap could have a profound impact on the course of the pandemic.

A global surge of infections in a world where billions of people remain unvaccinated not only threatens the health of vulnerable individuals but also increases the opportunity for the emergence of yet more variants. The disparity in the ability of countries to weather the pandemic will almost certainly deepen. And the news about limited vaccine efficacy against Omicron infection could depress demand for vaccination throughout the developing world, where many people are already hesitant or preoccupied with other health problems.

Most evidence so far is based on laboratory experiments, which do not capture the full range of the body’s immune response, and not from tracking the effect on real-world populations. The results are striking, however.

The Pfizer and Moderna shots use the new mRNA technology, which has consistently offered the best protection against infection with every variant. All of the other vaccines are based on older methods of triggering an immune response.

The Chinese vaccines Sinopharm and Sinovac — which make up almost half of all shots delivered globally — offer almost zero protection from Omicron infection. The great majority of people in China have received these shots, which are also widely used in low-and middle-income countries such as Mexico and Brazil.

A preliminary effectiveness study in Britain found that the Oxford-AstraZeneca vaccine showed no ability to stop Omicron infection six months after vaccination. Ninety percent of vaccinated people in India received this shot, under the brand name Covishield; it has also been widely used across much of sub-Saharan Africa, where Covax, the global Covid vaccine program, has distributed 67 million doses of it to 44 countries.

Researchers predict that Russia’s Sputnik vaccine, which is also being used in Africa and Latin America, will show similarly dismal rates of protection against Omicron.

Demand for the Johnson & Johnson vaccine had been surging in Africa, because its single-shot delivery regimen makes it easy to deliver in low-resource settings. But it too has shown a negligible ability to block Omicron infection.

Bars and restaurants in Ireland will be required to close early in the week leading up to Christmas, usually their busiest time of the year, as governments around Europe battle a new wave of Covid infections driven by the Omicron variant.

Restaurants, bars and public venues must reduce their hours and close at 8 p.m., beginning on Monday. Prime Minister Micheál Martin said that cases of the Omicron variant in Ireland were doubling every few days and that, for Ireland, the worst of the pandemic could be ahead.

“I’m apprehensive in terms of what this might mean in terms of the sheer scale of infection,” Mr. Martin told RTE, Ireland’s state broadcaster. “Which is why we can’t take risks — the great unknown being, how severe is this in terms of requiring hospitalizations and I.C.U.s, and just damaging people in terms of health?”

On Saturday, health authorities announced 7,333 new cases — double the number of the day before. Health authorities said that 35 percent of positive swab tests taken last Wednesday indicated the Omicron variant, suggesting that it would become the dominant variant in Ireland within days.

The new restrictions have been sharply criticized by trade bodies for bar owners and restaurateurs, and also by some lawmakers representing parties in Mr. Martin’s coalition government.

The Licensed Vintners Association, representing bar operators in the Dublin area, said that many of its members, already weakened by previous lockdowns, saw the new measures as “closure by camouflage.”

The Restaurants Association of Ireland called for the reintroduction of emergency payments to businesses that were forced to close completely in previous lockdowns. The government said it is considering such measures this week.

For Mr. Martin and his deputy prime minister, Leo Varadkar, the difficult choice between business needs and public health echoes their painful experience this time last year, when they gave in to calls to ease tight restrictions on socializing and entertainment so that Ireland could enjoy a “meaningful Christmas.”

Emergency restrictions were reintroduced on Christmas Eve last year, followed by a January lockdown, which further damaged the retail economy.

Jane Suiter, a politics and communications professor at Dublin City University, said that government policy is to contain overall levels of infection while keeping schools open. Ireland’s entertainment businesses, famously convivial at this time of year, seem to be an “easy target.”

“It’s hardest on people aged 18 to 30, who’ve already given so much,” she said. “My life isn’t really impacted at all, but my students’ lives are very deeply impacted.”

In neighboring Britain, the government is leaving open the possibility of imposing another round of restrictions, the country’s health secretary said on Sunday.

Scientific advisers have warned lawmakers that more action is needed, because the country’s surge is threatening to overwhelm its health system, even after the government announced a long-resisted coronavirus contingency plan earlier this month, urging people to work from home if possible and extending a face-mask mandate.

Over the weekend, Sadiq Khan, London’s mayor, declared a “major incident” — an emergency status that frees up resources — in the capital, and speculation has been swirling over the possibility of a short-term nationwide lockdown.

Britain’s deputy prime minister, Dominic Raab, said on Times Radio on Monday that 12 people in the country had died from Omicron. He did not rule out a further tightening of restrictions.

— Ed O’Loughlin

A booster shot of the Moderna coronavirus vaccine significantly raises the level of antibodies that can thwart the Omicron variant, the company announced on Monday.

The news arrives as Omicron rapidly advances across the world, and most coronavirus vaccines seem unable to stave off infection from the highly contagious variant.

Moderna’s results show that the currently authorized booster dose of 50 micrograms — half the dose given for primary immunization — increased the level of antibodies by roughly 37-fold, the company said. A full dose of 100 micrograms was even more powerful, raising antibody levels about 83-fold compared with pre-boost levels, Moderna said.

Both doses produced side effects comparable to those seen after the two-dose primary series. But the dose of 100 micrograms showed slightly more frequent adverse reactions relative to the authorized 50-microgram dose.

The results are based on laboratory tests that do not capture the full range of the body’s immune response against the virus. Although vaccines may not prevent infection from the variant, they are expected to prevent severe illness in the vast majority of people.

The data have also not been published or reviewed by independent experts. Moderna said it was preparing a manuscript with the data that would be posted online.

The pharmaceutical companies Pfizer and BioNTech announced earlier this month that a booster shot of their vaccine also increased the level of antibodies against Omicron.

Moderna tested a third shot of several versions of its vaccine, each in 20 people. Before boosting, all the individuals had low levels of antibodies that can prevent Omicron infection. At Day 29, after receiving a third shot, the 50-microgram and 100-microgram doses of the current vaccine both sharply increased antibody levels.

The company also tested “multivalent” booster shots that incorporate mutations seen in the Beta and Delta variants, many of which are also present in Omicron. Those continuing trials each have 300 to 600 people enrolled in them. The 50-microgram and 100-microgram doses of the multivalent boosters increased antibody levels to similarly high levels, Moderna said.

Given how quickly Omicron is marching through the world, Moderna said, the company will focus its near-term efforts on extra shots of the original vaccine. It also plans to test a booster shot that is specific to the Omicron variant early next year and to include Omicron in a multivalent booster.

“To respond to this highly transmissible variant, Moderna will continue to rapidly advance an Omicron-specific booster candidate into clinical testing in case it becomes necessary in the future,” said Stéphane Bancel, Moderna’s chief executive officer.

Two prominent Democratic senators, Elizabeth Warren of Massachusetts and Cory Booker of New Jersey, announced separately on Sunday that they had tested positive with a breakthrough case of the coronavirus.

Both senators disclosed their cases on Sunday, and said they were experiencing mild symptoms after being vaccinated and receiving a booster shot. Ms. Warren said she received the positive result Sunday, while Mr. Booker said his test result came back after he began experiencing symptoms Saturday.

News of the cases came barely a day after the Senate left Washington for the year and ahead of a planned address by President Biden to the nation on Tuesday to respond to the rapid spread of the Omicron variant.

Both senators called on the public to get vaccinated.

“I urge everyone who has not already done so to get the vaccine and the booster as soon as possible — together, we can save lives,” Ms. Warren wrote on Twitter, adding that she had received both a vaccine and a booster shot.

“I’m certain that without them I would be doing much worse,” Mr. Booker said in a statement. “I encourage everyone who is eligible to get vaccinated and boosted.”

President Biden will address Americans on Tuesday as his administration faces questions about how it will respond to the challenges of a pandemic that has persisted well beyond the administration’s expectations.

Mr. Biden “will announce new steps the Administration is taking to help communities in need of assistance,” Jen Psaki, the White House press secretary, wrote on Twitter on Saturday, “while also issuing a stark warning of what the winter will look like for Americans that choose to remain unvaccinated.”

Mr. Biden has both sounded an alarm over Omicron this month while also expressing optimism that the fast-spreading variant would not set back the progress the country has made.

For the unvaccinated, the president said on Thursday, “we are looking at a winter of severe illness and death — if you’re unvaccinated — for themselves, their families, and the hospitals they’ll soon overwhelm. But there’s good news: If you’re vaccinated and you had your booster shot, you’re protected from severe illness and death — period.”

The symptoms of the common cold are typically a stuffy head, the sniffles and body aches.

Now, this season, there’s a new one: panic.

As the latest coronavirus variant races through recently reopened offices, holiday parties and family gatherings, signs of an ailment that was once an annoying winter perennial eased with bed rest and chicken soup now set minds racing. In New York City, the slightest sniffle has people canceling holiday plans and packing coronavirus testing centers, where in recent days lines have stretched for blocks.

Is it a cold? Or is it Covid?