A third dose of the Pfizer/BioNTech Covid-19 vaccine can "strongly" boost protection against the Delta variant -- beyond the protection afforded by the standard two doses, new data released by Pfizer on Wednesday suggests.
The data posted online suggest that levels of antibodies that can target the Delta variant grow fivefold in people 18 to 55 who get a third dose of the vaccine.
Among people ages 65 to 85, the Pfizer data suggest that antibody levels that should protect against Delta grow 11-fold more than following a second dose.
However, the data, which involved tests of 23 people, have not yet been peer-reviewed or published. It's not clear if boosted antibody levels actually correlate to better protection, or if that extra protection is even needed. The US Centers for Disease Control and Prevention says the current vaccines protect people well against all the common variants.
he data also show that antibody levels are much higher against the original coronavirus variant and the Beta variant, first identified in South Africa, after a third dose.
Separately, Pfizer and its partner BioNTech released new safety and efficacy data for their coronavirus vaccine Wednesday, and said it shows protection holds up for at least six months, although it may start to wane slightly towards the end of that time. It found the overall efficacy was about 91% during the six months. Vaccine efficacy against severe Covid-19 was about 97%, the data show. The paper has not yet been peer-reviewed nor published in a journal. The data show that the vaccine's efficacy peaked at more than 96% from a week to around two months after receiving the second dose of vaccine, and then appeared to gradually decline to 83.7% four to six months later, with an average decline of about 6% over the last two months.
Pfizer said it anticipates submitting data on the third dose of its coronavirus vaccine to the FDA as soon as next month, said Dr. Mikael Dolsten, who leads worldwide research, development, and medical for Pfizer, during Wednesday's earnings call.
"We are in ongoing discussions with regulatory agencies regarding a potential third-dose booster of the current vaccine and, assuming positive results, anticipate an emergency use authorization submission as early as August," Dolsten said.