Based on evidence of a higher risk of infection six months after inoculation and the development of the highly contagious Delta form, Pfizer (PFE.N) and partner BioNTech (22UAy.DE) plan to seek US and European regulators in the next weeks to approve a booster shot of their COVID-19 vaccine.
In a joint statement, the US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) stated that Americans who have been completely vaccinated do not require a COVID-19 booster dose at this time.
The European Medicines Agency (EMA) said it was too early to say if more than the two shots presently required will be required, but it was convinced that the current regimen would be enough for the time being.
The need for booster shots have also been questioned by a number of scientists.
Mikael Dolsten, Pfizer’s chief scientific officer, said the vaccine’s recently reported drop in effectiveness in Israel was primarily attributable to infections in persons who were immunized in January or February. In June, the country’s health ministry reported that vaccine effectiveness in preventing infection and symptomatic disease had dropped to 64%.
“The Pfizer vaccine is highly active against the Delta variant,” Dolsten stated in an interview. But after six months, he added, “there likely is the risk of reinfection as antibodies, as predicted, wane.” Data would be submitted to the FDA within the next month, he added.
Pfizer did not disclose the entire set of Israeli data on Thursday, but promised to do so shortly.
“It’s a small data set, but I think the trend is accurate: Six months out, given that Delta is the most contagious variant we have seen, it can cause infections and mild disease,” Dolsten said.
The FDA and CDC said in a joint statement: “We are prepared for booster doses if and when the science demonstrates that they are needed.”
Pfizer’s own data from the United States showed the vaccine’s efficiency eroding to the mid-80s after six months against the strains circulating in the spring, according to Dolsten.
He emphasized that research from Israel and the UK suggests that the vaccination is still 95 percent effective against serious disease, despite falling antibody levels.
In a clinical trial conducted by the firms last year, the vaccine, which was developed by BioNTech in Germany, demonstrated 95 percent efficiency in avoiding symptomatic COVID-19.
Dolsten explained that preliminary data from the company’s own studies show that a third booster dose generates antibody levels that are five-to-10-fold higher than after the second dose, implying that a third dose will offer promising protection.
Pfizer has already been approached by a number of nations in Europe and internationally to consider booster doses, and some may begin providing them ahead of a potential US approval, he said.
Booster shots, Dolsten believes, are especially important in older age groups.
Dr. Eric Topol, a professor of molecular medicine and director of the Scripps Research Translational Institute in La Jolla, California, said that basing the decision on waning antibody protection ignores the importance of other components of the immune response, such as memory B cells, which can produce antibodies on demand when threatened by the virus.
“You need better studies to be able to assert that. It isn’t just neutralizing antibodies,” Topol asserted.
BioNTech has previously argued that, while antibodies are the body’s primary defense against an initial infection, the cellular immune response primarily protects against the disease spreading and worsening.
Pfizer is exploring on ways to raise manufacturing because boosters would drive up demand for vaccines while much of the globe remains unvaccinated, Dolsten noted.
Pfizer and BioNTech said a new version of the vaccine targeting the Delta variation is being developed, with a clinical trial set to begin in August, but that the present vaccination version had “the potential” to protect against the variant.
Pfizer anticipates the COVID-19 vaccine to be a big revenue generator for years, with sales expected to reach $26 billion in 2021. BioNTech announced in May that it has received 12.4 billion euros in income from vaccine supply deals so far this year, with more contracts on the way.