Pfizer seeking FDA approval of booster shot to protect against Delta variant

Pfizer-BioNTech says it will ask the Food and Drug Administration (FDA) to approve a booster dose, or a third shot, of its COVID-19 vaccine within the next month.

The drugmaker said on Thursday this step is based on evidence of greater risk of reinfection six months after two-dose treatment and due to the spread of the highly contagious Delta variant, now prevalent in several counties including Canada.

“While protection against severe disease remained high across the full 6 months, the observed decline in efficacy against symptomatic disease over time and the continued emergence of variants are key factors driving our belief that a booster dose will likely be necessary to maintain highest levels of protection,” Pfizer said in a statement.

Israel’s health ministry, a country that saw an increase in infections as a direct result of the Delta variant, said vaccine effectiveness in preventing both infection and symptomatic disease fell to 64 per cent in June.

Hours after Pfizer issued its statement, the FDA and Centers for Disease and Control issued a joint statement saying Americans do not need booster shots yet.

“Americans who have been fully vaccinated do not need a booster shot at this time,” the CDC and FDA said in the statement.

“We continue to review any new data as it becomes available and will keep the public informed. We are prepared for booster doses if and when the science demonstrates that they are needed.”

Speaking on Thursday, Pfizer Chief Scientific Officer Mikael Dolsten said while the Pfizer vaccine is highly effective against the Delta variant, after six months “there likely is the risk of reinfection as antibodies, as predicted, wane.”

Dolsten however did say that data from Israel and the U.K. suggests that even with decreasing or lower antibody levels, the vaccine remains around 95 per cent effective in protecting against severe disease.

“While we believe a third dose of BNT162b2 has the potential to preserve the highest levels protective efficacy against all currently known variants including Delta, we are remaining vigilant and are developing an updated version of the Pfizer-COVID-19 vaccine that uses a new construct based on the B.1.617.2 lineage, first identified in India and also known as the Delta variant,” Pfizer and BioNTech added.

The vaccine, developed with German partner BioNTech, showed 95 per cent efficacy in preventing symptomatic COVID-19 in clinical trials conducted within the last year.

Moderna CEO Stephane Bancel said in early May that a booster for his company’s vaccine would also likely be needed in the fight against transmissible variants.

Pfizer and Moderna vaccines have been widely distributed across Canada and its many provinces as the country’s vaccine rollout have greatly improved in recent months.

Canada’s top public health official says the country is “within reach” of fully vaccinating four out of every five eligible Canadians against COVID-19.

Dr. Theresa Tam says more than 40-million doses have been given so far, with 78 per cent of those 12 and older receiving at least one dose.