Being “fully vaccinated” but not boosted doesn’t prevent Omicron, the study found


Being "fully vaccinated" but not boosted doesn't prevent Omicron, the study found

Two vaccinations with the COVID-19 vaccine without an additional booster dose provide essentially no long-lasting protection against infection with Omicron, and coronavirus infection is as effective as a recent booster dose in preventing a new disease caused by Omicron, researchers reported Wednesday.

At the same time, any immunity to the highly contagious variant, whether through infection or vaccination, appears to offer significant and lasting protection against serious illness, hospitalization and death, the researchers found. And if you didn’t have the virus or the vaccine, doctors urged, it’s better to get the vaccine.

The findings, published in the New England Journal of Medicine, offer some of the best insights yet into the longevity of different types of coronavirus immunity and offer a glimpse into the future of the pandemic.

“COVID-19 will essentially be with us forever. It’s not really going away. But the question will be: will we somehow be able to live with it?” said Laith Jamal Abu-Raddad, infectious disease epidemiologist at Weill Cornell Medicine-Qatar and co-author of the study. “And the initial results we’re getting are actually very encouraging.”

The study is the latest of several examined nationwide data from Qatar, the small Middle Eastern nation of just under 3 million people.

Qatar’s population is significantly younger than most developed countries – only 9% of residents are over 50, compared to around 35% in the US. It’s also more diverse, with 89% of its residents being expatriates from 150 other nations. The country also has a robust coronavirus testing program, high COVID-19 vaccine uptake, and a centralized public health database that provides researchers with clean, clear data to analyze the impact of the vaccines over time.

For this latest study, the researchers examined data as the Omicron subvariants known as BA.1 and BA.2 raced through the country’s population from late December to late February.

They found that people who received both vaccinations of either Pfizer and BioNTech’s Comirnaty vaccine or Moderna’s Spikevax vaccine when they first became available, but then failed to boost their immune systems with booster shots im had essentially no protection against a mild to moderate case of COVID-19. Six months after their last vaccination, they were just as susceptible to a positive test and symptoms of illness as anyone else – but still showed strong resistance to major diseases.

Prior infection was approximately 46% effective in preventing symptomatic infection. A full vaccination and booster was approximately 52% effective. And natural immunity against a previous infection, as well as immunity against a vaccine and a booster shot, was the most effective of all, reducing the risk of COVID-19 by 77%.

These numbers represent a sharp decline from the early days of vaccines, when clinical trials showed them to be 94% to 95% effective at preventing even mild illness. But as the coronavirus accumulates mutations, vaccines become less effective at detecting the virus and blocking infection.

“The immune evasion is so much higher” with Omicron, Abu-Raddad said. It is “essentially a new virus”.

The time since the last surge in immunity from an infection or shot also erodes the body’s resistance to the type of infection that produces prominent symptoms and a second pink line on a home test.

“However,” Raddad said, “and I think that’s really the important part: immunity to severe COVID-19 was preserved really, really well.”

It might sound like a past infection would be just as useful as a vaccine to counteract Omicron, but doctors have a definite preference: get the shot, not the virus.

It is definitely much, much safer to get vaccinated than to get infected.”
– dr Jeffrey Klausner, an infectious disease specialist at USC’s Keck School of Medicine

“It’s definitely much, much safer to get vaccinated than to get infected,” said Dr. Jeffrey Klausner, an infectious disease specialist at USC’s Keck School of Medicine.

“The vaccine only presents a small part of the virus,” said Klausner. “If you get infected, the whole virus will spread throughout the body, it will cause different symptoms in different parts of the body, and increase your risk of long COVID or a longer duration of the disease.”

Previous studies have documented omicron’s infuriating ability to evade existing vaccine antibodies.

The Qatar group’s data complements this work by shedding light on immunity longevity, said Dr. Robert “Chip” Schooley, an infectious disease specialist at UC San Diego. “They have a much better understanding of the degradation of the immune response over time than we do in the US,” he said.

“Getting COVID right now — if you’re vaccinated and reasonably healthy — is more of a nuisance than a life-threatening event for most people,” Schooley said. “It’s a very different disease than two years ago when we had a largely unimmunized human population and a virus that first kicked at you.

“Now we have a virus that many of us have seen either through vaccination or through infection or a combination of both,” he added. “The playing field is much more balanced.”


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