Being ‘fully vaccinated’ but not boosted doesn’t prevent omicron, study finds

Being 'fully vaccinated' but not boosted doesn't prevent omicron, study finds

Two injections of the COVID-19 vaccine without an additional booster essentially offer no long-lasting protection against infection with omicron, and a coronavirus infection is as effective as a recent booster injection in preventing a new illness fueled by omicron, researchers reported on Thursday. Wednesday.

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

the resultspublished in the New England Journal of Medicine, it provides some of the best insights to date into the longevity of different types of immunity to coronavirus and offers insight into the future of the pandemic.

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

The study is the latest of several examining data from the entire country of Qatar, the tiny Middle Eastern nation of just under 3 million people.

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

For this most recent study, the researchers looked at data as the omicron subvariants known as BA.1 and BA.2 traversed the country’s population from late December to late February.

They found that people who had received both injections of Pfizer and BioNTech’s Comirnaty vaccine or Moderna’s Spikevax injection when they first became available, but then did not boost their immune systems with booster injections, had essentially no protection against a mild to moderate disease. case of COVID-19. Six months after their last injection, they were as susceptible to a positive test and disease symptoms as anyone else, but still showed strong resistance to severe disease.

A prior infection was approximately 46% effective in preventing a symptomatic infection. Being fully vaccinated and reinforced it was about 52% effective. And having natural immunity from a previous infection, as well as immunity from a vaccine and a booster, was the most effective of all, reducing the risk of COVID-19 by 77%.

Those numbers represent a sharp decline from the early days of vaccines, when clinical trials showed they were 94% to 95% effective in preventing even mild illness. But as the coronavirus accumulates mutations, vaccines become less effective at recognizing the virus and blocking infections.

“Immune evasion is much higher” with omicron, Abu-Raddad said. It is “essentially a new virus.”

The passage of time since the last boost of immunity from an infection or injection also erodes the body’s resistance to the type of infection that causes noticeable symptoms and a second pink line on a home test.

“However,” Raddad said, “and I think this is really the important part: Immunity against severe COVID-19 was really very much preserved.”

It may seem like a past infection is just as useful as a vaccine in countering Omicron, but doctors have an unequivocal preference: get vaccinated, not the virus.

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

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

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

Previous studies have documented omicron irritant skill to evade existing vaccine antibodies.

The data from the Qatar group adds to that work by shedding light on the longevity of immunity, he said. Dr Robert “Chip” Schooley, an infectious disease specialist at UC San Diego. “They have done a much better job of understanding the deterioration of the immune response over time than we have” in the US, she 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 is a very different disease than it was two years ago, when we had a largely non-immune human population and a virus attacking you for the first time.

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


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