The effectiveness of Pfizer's Covid-19 vaccine has steadily declined over time, dropping to around 84% around four to six months after the second dose for vaccinated people, according to CEO Albert Bourla.
The comments made on CNBC's "The Exchange" on Wednesday are based on the results of a new, company-funded study that has yet to be peer-reviewed. It comes when the drug maker clashes with U.S. health officials over the need for a third dose of Covid vaccine to bolster immunity protection.
The study found that the vaccine was most effective at 96.2% between one week and two months after the second dose. It decreased an average of 6% every two months, according to the study, which enrolled more than 44,000 people in the US and other countries. The effectiveness after "four to six months was about 84%," said Bourla.
Pfizer sells $ 7.8 billion in Covid vaccines in the second quarter and is increasing its vaccine sales forecast for 2021
“We have also seen data from Israel that immunity is waning and this is starting to affect what used to be 100% against hospitalization. Now, after the six month period, it's going to be below 90s and mid to high 80s, ”said Bourla.
"The good news is that we are very, very confident that a third dose, a booster, will bring the immune response to levels sufficient to protect against the Delta variant," added the executive, referring to to the highly contagious virus strain that is prevalent in the US and other countries around the globe. It is not uncommon for vaccines to degrade over time, stressed Bourla, adding that there is a precedent for three-dose vaccines against other diseases.
Pfizer plans to formally provide data to U.S. regulators by mid-August on the benefits of a third dose of Covid vaccine, Bourla said.
Earlier this month, when Pfizer first announced its plans, the Food and Drug Administration and Centers for Disease Control and Prevention issued a joint statement that pushed the company back, saying, “Americans who have been fully vaccinated don't need a booster at this time. "
The CDC and the World Health Organization do not currently recommend a Covid booster.
Dr. Kate O'Brien, WHO director for Immunization, Vaccines and Biologics, said Wednesday the organization is still researching whether a booster vaccination is needed to increase protection.
"We are very aware that there is not enough information at this point to make a recommendation," O’Brien said in a Q&A interview posted on the organization's social media accounts. "Again, this is a very hot topic and there is a lot of research going on to make an evidence-based recommendation."
The results of the Pfizer-sponsored study surfaced a day after the CDC reversed course in accordance with its previous guidelines, recommending fully vaccinated Americans living in areas with high rates of Covid infection return to wearing face masks indoors.
Coronavirus cases have risen across the country in the past few weeks, an increase health officials attribute to the Delta variant. While officials say the majority of Covid hospital admissions and deaths are from unvaccinated people, the Delta variant is so contagious that vaccinated people can transmit the virus just as easily as unvaccinated people, even in asymptomatic cases, CDC director Rochelle Walensky said on Tuesday.