Citing New Data, Pfizer Outlines Case for Booster Shots
Pfizer reported on Wednesday that the potency of its two-dose Covid vaccine declines slightly over time, but still provides long-lasting and robust protection against serious illness. The company has suggested that a third injection could improve immunity, but whether boosters will be badly needed is far from clear, which is the subject of heated debate among scientists.
So far, federal health officials have said boosters for the general population are unnecessary. And experts have questioned whether those vaccinated should receive more doses when so many have yet to be vaccinated.
“There isn’t enough evidence at the moment to support that this is somehow the best use of resources,” said Natalie Dean, a biostatician at Emory University in Atlanta.
Still, the results raise questions about the ability of the Pfizer vaccine to prevent infection in the months to come. And with the resurgence of coronavirus cases in many states, the data may influence the Biden administration’s deliberations on providing boosters for the elderly.
If third shots are allowed for the general population, boosters would likely be a multibillion dollar business for Pfizer.
In a study published online but not yet peer-reviewed or published in a scientific journal, scientists at Pfizer and BioNTech reported that the vaccine had an extremely high efficacy rate of around 96% against Covid-19 symptomatic during the first two months following the second. dose. But the figure declined by about 6% every two months after that, dropping to 83.7% after about four to six months.
Against serious illnesses, however, the vaccine’s effectiveness has remained at around 97 percent.
“This drop is very slight – I wouldn’t say it’s decreasing,” said Akiko Iwasaki, an immunologist at Yale University. She saw no evidence in the new study that boosters should be used for the general population. “This data does not support a need for this at this time,” she said.
The results are consistent with what scientists have learned about how the immune system repels viruses. Antibodies are the only defense to prevent infection, but their levels usually drop within months of getting vaccinated or recovering from the disease. If the coronavirus takes hold, immune cells can infiltrate to destroy infected cells and make new antibodies.
This lasting defense produced by the vaccine may explain how the virus can sometimes reproduce in the nose – producing a cold or sore throat – but fail to reach the lungs where it can cause serious illness.
“Anything that is initiated by the vaccine is capable of combating this spread which ultimately leads to serious illness,” said Dr Iwasaki. “It’s probably not going down at all. “
The study period ended before the rise of the Delta variant, the highly contagious version of the virus that now dominates in the United States and makes vaccines somewhat less effective against infection.
The results come from 42,000 volunteers in six countries who participated in a clinical trial that Pfizer and BioNTech began last July. Half of the volunteers received the vaccine, while the other half received a placebo. The two groups received two injections three weeks apart.
The researchers compared the number of people in each group who developed symptoms of Covid-19, which were then confirmed by a PCR virus test. When the companies announced their first batch of results, the vaccine showed 95% efficacy against symptomatic Covid-19.
In other words, the risk of getting sick was reduced by 95% in the group that received the vaccine, compared to the group that received the placebo. This result – the first for any Covid-19 vaccine – brought an exhilarating dose of hope to the world in December as it weathered what had been the biggest wave of the pandemic.
Since then, the Pfizer-BioNTech vaccine has made up the majority of injections Americans have received, with more than 191 million doses administered to date, according to the Centers for Disease Control.
In the new study, researchers followed the volunteers for six months after vaccination, until March 13. Over the entire period, the researchers estimated that the vaccine’s effectiveness was 91.5% against symptomatic Covid-19. (The study did not measure the rate of asymptomatic viral infections.)
But during this period, the efficiency gradually declined. Between one week and two months after the second dose, the figure was 96.2 percent. In the period of two to four months after vaccination, the effectiveness fell to 90.1 percent. From four months after vaccination to the March deadline, the figure was 83.7%.
Understanding the State of Vaccination Mandates in the United States
These numbers still describe a remarkably effective vaccine, however, and may not convince critics that booster shots are badly needed.
The study follows data from Israel suggesting that Pfizer-BioNTech’s protection may decrease there. But experts fended off the rush to approve a recall there. The data has too many sources of uncertainty, they say, to make an accurate estimate of the decrease in efficiency. For example, the epidemic caused by the Delta first hit parts of the country with high vaccination rates and then affected other areas.
“Such an analysis is still very uncertain,” said Doron Gazit, a physicist at Hebrew University who analyzes trends in Covid-19 for the Israeli government.
Earlier Wednesday, Pfizer reported that a third dose of its vaccine dramatically increases blood levels of antibodies to several versions of the virus, including the Delta variant.
The results were similar for antibodies produced against the original virus and the beta variant, which was first identified in South Africa. Pfizer and BioNTech plan to publish more definitive research in the coming weeks.
The announcement was a preliminary overview of the data contained in an income statement. And while antibody levels are an important measure of immunity, they’re not the only measure. The body has other defenses that repel infection.
Pfizer also said in its statement that vaccines for children ages 5 to 11 could be available as early as the end of September. The vaccine is already licensed in the United States for anyone 12 years of age and older.
Pfizer’s vaccine has generated $ 7.8 billion in revenue over the past three months, the company said, and is on track to generate more than $ 33.5 billion this year.
The vaccine is poised to generate more sales in a single year than any previous medical product, and with a large margin. Pfizer did not disclose its exact profits on the vaccine, but reiterated its previous estimate that its profit margins on the vaccine would be in the range of 20%. Even if the drugmaker’s profits are in the lower end of that range, it would represent around $ 3 billion in profit so far this year.
Rebecca robbins contributed reports.
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