Pfizer/BioNTech are using preliminary Phase 1 data to start the process of asking the FDA to evaluate a third booster dose. That Phase 1 data found that people given a 3rd shot 8-9 months after their primary doses had a boosted immune response, and higher neutralizing antibody levels against the Delta variant compared to people who received the original 2 doses. The FDA and CDC are still not recommending booster doses for all. It's not clear when or if the agencies might recommend booster doses. The companies are suggesting that giving a booster dose from six to 12 months after the initial vaccination will help maintain a high level of protection.