Pfizer’s PREVENAR 20 Vaccine Study: A Safety Investigation in Infants

Pfizer Inc ((PFE)) announced an update on their ongoing clinical study.

Study Overview: Pfizer Inc. is conducting a study titled PREVENAR 20 SUSPENSION LIQUID FOR INJECTION SPECIAL INVESTIGATION to assess the safety of the 20-valent Pneumococcal Conjugate Vaccine (PREVENAR 20) in infants aged between two to six months. The study aims to observe the vaccine’s safety under real-world clinical conditions in Japan, focusing on infants receiving the vaccine for the first time.

Intervention/Treatment: The intervention being tested is the 20-valent Pneumococcal Conjugate Vaccine, a biological treatment administered as a 0.5mL injection. It is intended to protect infants from pneumococcal infections.

Study Design: This observational study follows a cohort model with a prospective time perspective. It involves infants who are vaccinated with PREVENAR 20, tracking them from the first vaccination until 28 days after the fourth vaccination to monitor side effects.

Study Timeline: The study began on November 25, 2024, with the primary completion and estimated completion dates yet to be disclosed. The last update was submitted on August 12, 2025, indicating ongoing progress.

Market Implications: This study update could positively impact Pfizer’s stock performance by reinforcing investor confidence in the company’s vaccine portfolio. As the vaccine market remains competitive, successful safety outcomes could strengthen Pfizer’s position against competitors.

The study is ongoing, and further details are available on the ClinicalTrials portal.