While getting two doses of the vaccine creates a strong immune response that reduces the risk of serious illness by more than 90%, protection from mild and asymptomatic infections gradually declines.
That’s why Pfizer has requested and obtained FDA clearance to add boosters to many people whose vaccinations have finished six months.
“I think we would expect immunity to wane slowly, over time, but it’s not a cause for people to panic,” said Dr. Ann Fulsey, a viral respiratory disease specialist at the University of Rochester School of Medicine.
“It’s not like suddenly one day you’re just as vulnerable as you were before you were vaccinated,” added False, who helps lead clinical trials of Covid-19 vaccines.
“All vaccines stand up well — Pfizer, Moderna, Johnson & Johnson — for severe disease,” Fulsi told CNN. “Now, that doesn’t mean we may not eventually get to a point where we really need people to get boosters to prevent more severe disease. But, in fact, the majority of penetrating infections are the common cold, perhaps the flu-like illness — not the dreaded ones we had before.”
“So my main message is, don’t panic. you will be fine.”
That didn’t stop the Americans from flocking to get reinforcements. Last week, more people got booster doses than people got the first round of the coronavirus vaccine. By Friday, more than 7 million Americans had received either a booster shot or a third round of vaccines authorized for people with promising immune conditions who likely did not get adequate responses to the first two shots.
This week, two more studies add to the mounting evidence that immunity from the Pfizer vaccine drops.
One Israeli study that covered 4,800 health care workers and showed that antibody levels decline rapidly after two doses of the vaccine, “particularly among men, among people aged 65 or older, and among immunosuppressed people.”
A second study from Qatar showed that protection from the Pfizer vaccine peaked in the first month after vaccination and then began to fade.
“These findings suggest that a large proportion of the vaccinated population may lose protection against infection in the coming months, possibly increasing the potential for new pandemic waves,” the team wrote in a report published in the New England Journal of Medicine.
How can protection against mild or asymptomatic infection be diminished while still being strong against severe disease?
That’s because the human immune system is complex.
Antibodies are the first line of defense, as they prevent the virus from reaching some cells of the body. This is the protection that begins to fade after the passage of time.
But there is a second line of defense – cell-based immunity. Cells called B cells and T cells can take longer to form than antibodies, but they provide a longer-lived, broader defense against infection and are responsible for the decrease in severe infections.
So, while people may be at risk of developing a mild illness after they are vaccinated, they are less likely to get really sick, or end up in the hospital or die.
“But there are a lot of reasons why people don’t want to get sick,” Falsey said. They do not want to pass it on to their loved ones. People don’t want to pass it on to young children who can’t get vaccinated yet,” False said.
The US Centers for Disease Control and Prevention has been saying for months, that’s why even fully vaccinated people need to continue to take precautions against infection — wear masks when there are a lot of other people who may or may not be vaccinated, especially indoors, and make sure So. The rooms are well ventilated.