They confirm the decrease in immunity of the Pfizer vaccine 0:41
(CNN) -
While receiving two doses of the covid-19 vaccine creates a strong immune response that reduces the risk of severe disease by more than 90%, protection against milder, asymptomatic infections gradually diminishes.
That is why Pfizer applied for and received authorization from the US Food and Drug Administration (FDA) to offer a booster vaccine for many people who received their last dose six months ago.
But should others also look for the booster dose?
How much should people care?
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"I think we expect immunity to decline slowly, over time, but it's not a reason for people to panic," said Dr. Ann Falsey, a specialist in viral respiratory diseases at the University of Rochester School of Medicine. .
"It's not that suddenly one day you are completely susceptible, as you were before you were vaccinated," added Falsey, who helps lead clinical trials of COVID-19 vaccines.
"All vaccines hold up pretty well, Pfizer, Moderna and Johnson & Johnson, for serious diseases," Falsey told CNN.
"Now, that's not to say that eventually we won't get to a point where we really need reinforcements to prevent more serious illnesses. But in reality, most emerging infections are colds, perhaps similar illnesses to flu, not the scary illnesses we faced before. So my main message is: don't panic. You're going to be fine. "
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That hasn't stopped Americans from flocking to get their booster shot.
Last week, more people received the booster vaccine than those who received their first round of a coronavirus vaccine.
By Friday, more than seven million Americans had received the booster shot from the third round of vaccines licensed for people with immunocompromised conditions that probably did not get an adequate response to the first two injections.
This week, two more studies added to mounting evidence that Pfizer's vaccine immunity is lowered.
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A study from Israel covered 4,800 healthcare workers and showed that antibody levels drop rapidly after two doses of the vaccine, "especially among men, among people 65 and older, and among people with immunosuppression."
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A second study from Qatar showed that the protection of the Pfizer vaccine peaked in the first month after vaccination and then begins to decline.
"These findings suggest that a large proportion of the vaccinated population could lose their protection against infection in the coming months, perhaps increasing the potential for new epidemic waves," the team wrote in a report published in the New England Journal of Medicine.
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How can you decrease protection against mild or asymptomatic infection while staying strong against serious illness?
It is because the human immune system is complex.
Antibodies form the first line of defense, preventing a virus from entering some cells in the body.
This is the protection that starts to wear off after a while.
Questions from the audience about the coronavirus: If a vaccinated person gets COVID-19, does it increase their immunity or is it longer lasting?
But there is a second line of defense: cell-based immunity.
Cells called B cells and T cells may take longer to generate than antibodies, but they provide a more comprehensive and lasting defense against infection and are responsible for reducing serious infections.
So while people can be susceptible to mild illnesses after being vaccinated, they are much less likely to actually get sick, end up in the hospital, or die.
"But there are many reasons why people don't want to get sick. They don't want to infect their loved ones. People don't want to infect young children who cannot yet get vaccinated," Falsey said.
.
The Centers for Disease
Control and Disease Prevention (CDC, for its acronym
in
English) have said for months that is why even those fully vaccinated should continue to
take precautions against infection: wear masks when many other people who may or may not be vaccinated, especially indoors, and make sure rooms are well ventilated.
The FDA is considering requests from Moderna and Johnson & Johnson to authorize booster doses of their vaccines.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has said that he believes a third dose of the vaccine will become part of the standard regimen against COVID-19.
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"They just don't need to run to drugstores and panic."
People getting the booster dose now should have been among the first to get vaccinated, in January, February, and March.
This includes people 65 and older, adults with conditions who are at risk for serious illness, and people in occupations or living conditions are at higher than average risk of infection.
Everyone else should wait for now.
"They just don't need to run to drugstores and panic," Falsey said.
These southern states have fully vaccinated less than a third of eligible teens.
That difference could increase with younger children, according to an expert
People should not go and get booster doses if it has not been six months since the last dose of the Pfizer vaccine, because they will not get a better immune response, Fauci said at a briefing at the White House last month.
"There will be temptations, for example, for people who were recently vaccinated not to wait for the six-month period," Fauci said.
But waiting several months after the initial immunization to boost helps produce a stronger response.
The cells of the immune system that help restore weakened immunity respond more strongly if they are allowed to enter a resting state after the first round of vaccination.
That said, most people should eventually plan to get the booster shot, Falsey said.
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"It will probably happen for any of the vaccines, not just Pfizer; we will benefit by increasing immunity. That is not the same as saying it is critically necessary," he said.
While people who have recovered from an infection have some protection, they are even more protected if they also get vaccinated.
"I think relying on your own natural immunity because you feel like you are a strong person is like playing Russian roulette," Falsey said.
Even apparently healthy young people have become seriously ill from COVID-19 and have died from it.
"I would never depend on my natural immunity alone to weather this virus. It is a very, very bad factor," Falsey said.
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