Pfizer/ BioNTech is set to seek approval for booster shots amid concerns surrounding an incoming wave of the Delta variant.
The company has announced that it will seek regulatory approval for a third dose of their Covid-19 vaccine.
They have also confirmed that trials are currently underway to develop a Delta specific vaccine as a precaution.
The move comes following reports that efficacy has dropped off slightly in Israel after six months.
"While protection against severe disease remained high across the full six months, a decline in efficacy against symptomatic disease over time and the continued emergence of variants are expected," a statement from the two companies said.
"The companies expect to publish more definitive data soon as well as in a peer-reviewed journal and plan to submit the data to the FDA (Food and Drug Administration), the EMA (European Medicines Agency) and other regulatory authorities in the coming weeks,"
The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) said, however, in a joint statement that Americans who have been fully vaccinated do not need a booster COVID-19 shot at this time.
Pfizer's chief scientific officer, Mikael Dolsten, said the recently reported dip in the vaccine's effectiveness in Israel was mostly due to infections in people who had been vaccinated in January or February.
The country's health ministry said vaccine effectiveness in preventing both infection and symptomatic disease fell to 64% in June. "The Pfizer vaccine is highly active against the Delta variant," Dolsten said in an interview.
But after six months, he said, "there likely is the risk of reinfection as antibodies, as predicted, wane."
The first batch the Delta vaccine has been manufactured at BioNTech's facility in Mainz, Germany.
Pfizer/BioNTech anticipate the clinical studies will begin in August, subject to regulatory approvals.
