Citing the Delta Variant, Pfizer Will Pursue Booster Shots and a New Vaccine July 9, 2021 Auto Bot AstraZeneca PLC, BioNTech SE, Clinical Trials, Coronavirus (2019-nCoV), Disease Rates, Immune System, Pfizer Inc, Stockpiling, Vaccination and Immunization, your-feed-science 0 Scientists were critical of the announcement, pointing to evidence that the current two-dose regimen is powerfully effective against the coronavirus.