Coping with COVID: Second vaccine by Pfizer and BioNTech shows fewer side effects

Plans for a large-scale trial to be conducted with Pfizer and BioNTech’s first vaccine (referred to as B1) were soon altered, the companies instead conducting the trial using a second vaccine, called B2.

On July 1, the companies presented data on B1, anticipating using it in the trial. Less than a month later on July 27, the plan had changed, switching out their first vaccine B1 for the latest B2.

According to Pfizer and BioNTech, B2 seemed to generate a similar immune response yet fewer side effects when used in a smaller trial of 332 people.

Results for the smaller-scale trial showed that overall, individuals experienced fewer adverse events tied to the vaccine.

“Obviously, the better tolerated the vaccine, the more I think it will encourage public acceptance of a broad immunization,” William Gruber, senior vice president of vaccine clinical research and development at Pfizer said. “Both would have been great candidates. We were fortunate that B2 actually satisfied having both a favorable immune profile and fewer reactions.”

Pfizer said that data from the ongoing B2 vaccine trial of 30,000 could arrive by October and if successful, both Pfizer and Biotech could seek approval as early as that month.