Most vaccines around the world are unlikely to prevent infection with Omicron


A growing body of preliminary research suggests that the Covid vaccines used in most countries around the world offer almost no defense against infection with the highly contagious variant of Omicron.

All vaccines still seem to offer a significant degree of protection against serious illnesses caused by Omicron, which is the most crucial goal. But only Pfizer and Moderna vaccines, when boosted by a booster, seem to have early success in stopping infections, and these vaccines are not available in most countries.

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

A global wave of infections in a world where billions of people still go unvaccinated not only threaten the health of vulnerable people, but also increase the possibilities of even more variants emerging. The disparity in the ability of countries to overcome the pandemic will almost certainly worsen. And news about the vaccine’s limited efficacy against Omicron infection could reduce demand for vaccination in developing countries, where many people are already hesitant or concerned about other health concerns.

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

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

China’s Sinopharm and Sinovac vaccines – which account for almost half of all vaccines given worldwide – offer almost no protection against infection with Omicron. The vast majority of Chinese have received these injections, which are also widely used in low- and middle-income countries like Mexico and Brazil.

A preliminary efficacy study in Britain found that the Oxford-AstraZeneca vaccine showed no ability to stop Omicron infection six months after vaccination. Ninety percent of people vaccinated in India received this vaccine, under the brand name Covishield; it has also been used extensively 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 used in Africa and Latin America, will show equally dismal rates of protection against Omicron.

Demand for the Johnson & Johnson vaccine had increased in Africa, as its single injection schedule facilitates administration in low-resource settings. But it also showed negligible ability to block Omicron infection.

Antibodies are the first line of defense induced by vaccines. But the injections also stimulate the growth of T cells, and preliminary studies suggest that these T cells still recognize the Omicron variant, which is important for preventing serious disease.

“What you lose first is protection against mild, asymptomatic infections, what you keep much better is protection against serious illness and death,” said John Moore, virologist at Weill Cornell Medicine. At New York. He called it “a silver lining” as Omicron so far seems less lethal than the Delta variant.

But that protection won’t be enough to stop Omicron from causing global disruption, said J. Stephen Morrison, director of the Global Health Policy Center at the Center for International and Strategic Studies.

“The scale of the infection will overwhelm health systems, just because the denominator is potentially so large,” he said. “If you have an explosion of infection all over the world, shock, what is the world like on the other side?” Is it “The war is over” or “The war has just entered another phase”? We haven’t started to think about all of this.

People with breakthrough cases may only have asymptomatic infection or mild illness, but they can pass the virus to unvaccinated people, who could become more seriously ill and become a source of new variants.

Dr Seth Berkley, chief executive of Gavi, the global vaccine alliance, said more data was needed before drawing conclusions about the efficacy of vaccines against Omicron – and that accelerated vaccination should continue to be in focus. center of the pandemic response.

Preliminary data from South Africa suggests that with Omicron there is a much higher chance that people who have previously had Covid will be re-infected than with the original virus and previous variants. But some public health experts say they believe countries that have already gone through brutal waves of Covid, such as Brazil and India, may have a tamponade against Omicron, and vaccination after infection produces levels of infection. ‘high antibodies.

“The combination of vaccination and exposure to the virus appears to be stronger than the vaccine alone,” said Ramanan Laxminarayan, epidemiologist. India, he noted, has an adult vaccination rate of only around 40 percent, but 90 percent exposure to the virus in some areas.

“Without a doubt, Omicron is going to flood India,” he said. “But I hope India is protected to some extent due to vaccination and exposure.”

China doesn’t have this layer of protection to back up its weak vaccines. Due to China’s aggressive efforts to stop the spread of the virus within its borders, relatively few people have been exposed yet. It is estimated that only 7% of people in Wuhan, where the pandemic began, have been infected.

Much of Latin America has relied on Chinese and Russian vaccines, and on AstraZeneca. Mario Rosemblatt, professor of immunology at the University of Chile, said more than 90 percent of Chileans had received two doses of a vaccine, but the vast majority of them were Coronavac, the Sinovac vaccine. High vaccine coverage combined with early reports that Omicron is not causing serious illness is leading to a false sense of security in the country, he said.

“We have to make people understand that it does not work like that: if you get high transmissibility, you are going to have the health care system saturated because the number of sick people will be higher,” he said.

Brazil recommended that all vaccinated people receive a third dose, and it has started using Pfizer’s vaccine for all boosters, but only 40 percent of those vaccinated showed up for the additional vaccine. Dr Amilcar Tanuri, a virologist at the Federal University of Rio de Janeiro, said with cautious optimism that the high levels of previous exposure to Covid could mitigate the impact of Omicron, but noted that Brazilians most vulnerable , vaccinated first, received Coronavac and tens of millions more received AstraZeneca.

Mr Morrison called Omicron’s ability to evade immunization protection a “massive setback” for low- and middle-income countries, where, far from any discussion of recalls, the focus is still on the first vaccines.

“The world is divided into two parts, isn’t it? ” he said. “These are the ones who have a quick path to boosters compared to the ones who have had very limited progress and all of a sudden they’re subject to this new whip.”

Only 13% of people in Africa have received at least one dose of a Covid vaccine.

Dr Laxminarayan said the Indian government, to which he is an occasional advisor, is considering booster shots, but the Delta variant still poses a significant threat in India and two doses of the vaccine offer protection against Delta. This presents the government with a difficult choice between focusing on giving two doses to unvaccinated, or only partially vaccinated, people, or trying to provide boosters to older people and those with high-risk health conditions as protection against Omicron.

News that mRNA-free vaccines offer little protection against Omicron infection could further erode demand for vaccines in countries that are already struggling to grow demand, Morrison said.

“It calls into question the full value of vaccines,” he said. “If you’re that far behind and you have it, it will fuel anti-vaccine sentiment and weaken confidence.”

Tolbert Nyenswah, a senior researcher at the Johns Hopkins Bloomberg School of Public Health, said the emerging threat to countries in the South that have relied on mRNA-free vaccines was an indictment against the failure of rich countries to share this technology or to help increase production. points in low- and middle-income countries.

As a result, dangerous variants will continue to emerge in areas with low vaccination coverage and prolong the pandemic, predicted Dr Nyenswah, who served as Liberia’s deputy health minister during that country’s worst Ebola outbreak.

Dr Berkley de Gavi said it would be a big mistake for countries to relax their vaccination campaign or assume that only mRNA vaccines are worth distributing.

“We can see a situation where countries say, ‘If developed countries don’t want these vaccines, then we don’t want these vaccines,” he said. “It would of course be a misinterpretation if these vaccines were found to prevent serious illness and death.”

Lynsey chutel, Carl Zimmer and Emilie Schmall contributed reports.

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