Pfizer reported on Wednesday that the potency of the two-dose Covid vaccine wanes slightly over time, but still provides lasting and robust protection against serious diseases. The company has suggested that a third shot could improve immunity, but it’s still far from clear whether boosters will be widely needed, a topic of heated debate among scientists.
So far, federal health officials have said boosters are unnecessary for the general population. And experts have questioned whether people who have been vaccinated should take more doses while many people have not yet been vaccinated.
“There is currently not enough evidence to support that this is the best use of resources,” said Natalie Dean, a biostatistician at Emory University in Atlanta.
Still, the findings raise questions about how well the Pfizer vaccine will prevent infection in the coming months. And with coronavirus cases rising again in many states, the data Biden administration’s talks on providing boosters for old people.
If the third shot clears for the general population, boosters will likely represent a multi-billion dollar business for Pfizer.
In to work Pfizer and BioNTech scientists reported that the vaccine had a very high 96 percent efficacy rate against symptomatic Covid-19 during the first two months following the second dose. However, that figure dropped by about 6 percent every two months thereafter, to 83.7 percent after about four to six months.
Against severe disease, however, the effectiveness of the vaccine remained stable at about 97 percent.
“This decrease is very slight — I wouldn’t say it has decreased,” said Akiko Iwasaki, an immunologist at Yale University. The new study didn’t see any evidence that boosters should be used for the general population. “These data do not currently support the need for this,” he said.
The findings match what scientists have learned about how the immune system fends off viruses. Antibodies are the only defense to prevent an infection, but their levels typically drop in the months after vaccination or recovery from illness. If the coronavirus takes hold, immune cells can get in to destroy infected cells and make new antibodies.
This persistent defense produced by the vaccine may explain why the virus sometimes breeds in the nose and causes a cold or sore throat, but does not reach the lungs where it can cause serious illness.
Dr. “Everything included in the vaccine can fight this spread, which ultimately leads to serious illness,” said Iwasaki. “It probably won’t decrease at all.”
The period of study ended before the rise of the Delta variant, the highly contagious version of the vaccine-producing virus that now dominates the United States. slightly less effective against infection.
The findings come from 42,000 volunteers in six countries who participated in a clinical trial that Pfizer and BioNTech started last July. Half of the volunteers received the vaccine, while the other half received a placebo. Both groups received two shots three weeks apart.
The researchers compared the number of people in each group who developed symptoms of Covid-19, which was then confirmed by a PCR virus test. When the companies announced their first batch results, the vaccine showed efficacy against symptomatic Covid-19. 95 percent.
In other words, the risk of getting sick was 95 percent reduced in the vaccinated group compared to the placebo group. This result – the first for any Covid-19 vaccine – brought a refreshing dose of hope to the world in December, the biggest wave of the pandemic.
Since then, the Pfizer-BioNTech vaccine has made up the majority of the vaccines Americans receive, with more than 191 million doses given so far. by the way to the Centers for Disease Control.
In the new study, the researchers followed the volunteers for six months after the vaccine, through March 13. The researchers estimated the efficacy of the vaccine against symptomatic Covid-19 over the entire period to be 91.5 percent. (The study did not measure the rate of asymptomatic virus infections.)
However, during this time, activity gradually declined. One week to two months after the second dose, the figure was 96.2 percent. In the two to four months following vaccination, efficacy fell to 90.1 percent. Until the March cutoff, four months after vaccination, that figure was 83.7 percent.
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However, these numbers still describe a highly effective vaccine and may not convince critics that booster shots are widely needed.
Study by Pfizer-BioNTech of Israel there may be a decrease in protection. But there are experts pushed back against the rush to approve a supporter there. They say the data is too much of a source of uncertainty to make an accurate estimate of how much activity has decreased. E.gThe delta-borne outbreak first hit areas of the country with high vaccination rates and then other areas.
“Such an analysis is still quite uncertain,” said Doron Gazit, a Hebrew University physicist who has analyzed Kovid-19 trends for the Israeli government.
Earlier Wednesday, Pfizer reported that the third dose of its vaccine significantly increased blood levels of antibodies against various versions of the virus, including the Delta variant.
Results were similar for antibodies produced against the original virus and the Beta variant first identified in South Africa. Pfizer and BioNTech hope to publish more definitive research in the coming weeks.
The announcement was a preliminary snapshot of the data contained in an earnings statement. Although antibody levels are an important measure of immunity, they are not the only measure. The body has other defenses that repel infection.
Pfizer also said in a statement that vaccines for children ages 5 to 11 could be ready by the end of September. The vaccine is already approved in the United States for anyone aged 12 years and older.
The company said Pfizer’s vaccine has generated $7.8 billion in revenue over the past three months and is on track to generate more than $33.5 billion this year.
The vaccine is poised to sell in a single year, more than any previous medicinal product, and by a wide margin. Pfizer did not disclose its exact profit on the vaccine, but reiterated its previous estimate that profit margins on the vaccine will be in the high 20 percent range. Even if the drugmaker’s profit falls at the lower end of this range, it’s about $3 billion in profits so far this year.
Rebecca Robbins contributing reporting.