Two injections of COVID-19 vaccine without an additional booster provide essentially no lasting protection against omicron infection, and a coronavirus infection is as effective as a recent booster injection in preventing a new disease fueled by omicron. 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 long-lasting protection against serious illness, hospitalization and death, the researchers found. And if you haven’t had the virus or the vaccine, doctors have urged, you better get vaccinated.
The findings, published in the New England Journal of Medicine, provide some of the best knowledge yet on the longevity of different types of coronavirus immunity and offer insight into the future of the pandemic.
“COVID-19 is going to stay with us basically forever. It’s not really going away. But the question will be: Will we be able to live with this somehow? said Laith Jamal Abu-Raddad, infectious disease epidemiologist at Weill Cornell Medicine-Qatar and co-author of the study. “And the first results we’re getting are actually very encouraging.”
The study is the latest of several examining national data from Qatar, the tiny Middle Eastern nation with just under 3 million people.
Qatar’s population is considerably younger than that of most developed countries – only 9% of residents are over 50, compared to about 35% in the United States. It is also more diverse, given that 89% of its residents are expats from 150 other countries. 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 effects of vaccines. over time.
For this most recent study, researchers looked at data as the omicron subvariants known as BA.1 and BA.2 tore through the country’s population from late December to late February.
They found that people who received both injections of Pfizer and BioNTech’s Comirnaty vaccine or Moderna’s Spikevax injection when they first became available, but then neglected to boost their immune systems with booster shots had essentially no protection against mild to moderate infection. cases of COVID-19. Six months after their last vaccine, they were just as susceptible to a positive test and to symptoms of the disease as anyone else, but still showed strong resistance to severe disease.
Prior infection was approximately 46% effective in preventing symptomatic infection. Being fully vaccinated and boosted was about 52% effective. And having natural immunity to a previous infection as well as immunity to a vaccine and a booster was the most effective of all, reducing the risk of COVID-19 by 77%.
These figures represent a sharp drop from the early days of vaccines, when clinical trials showed them to be 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 so much higher” with omicron, Abu-Raddad said. It is “essentially a new virus”.
The time that has elapsed since the last immunity boost against an infection or vaccine also erodes the body’s resistance to the type of infection that causes noticeable symptoms and a pink second line when tested at home.
“However,” Raddad said, “and I think that’s really the important part: immunity against severe COVID-19 has been preserved really very well.”
It may seem that a past infection is just as useful as a vaccine against 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,” said Dr. Jeffrey Klausner, an infectious disease specialist at USC’s Keck School of Medicine.
“The vaccine only presents a small piece of the virus,” Klausner said. “The whole virus, if you get infected, is going to spread throughout the body, it’s going to cause different symptoms in different parts of the body and increase your risk of long COVID or prolonged illness.”
Previous studies have documented omicron’s irritant ability to evade existing vaccine antibodies.
The Qatar group’s data adds to that work by shedding light on the longevity of immunity, said Dr. Robert “Chip” Schooley, an infectious disease specialist at UC San Diego. “They’ve done a much better job of understanding immune response degradation over time than we” in the United States, 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 attacking you for the first time.
“Now we have a virus that many of us have seen either through vaccination or infection or a combination of both,” he added. “The playing field is much more even.”