Pfizer (PFE) Status Update summary

Strategic Focus and Program Overview

• Vaccines are a core growth pillar, with a focus on addressing unmet needs in infectious diseases, especially bacterial pathogens, including C. difficile.

• The C. difficile vaccine program is a key part of the bacterial vaccine portfolio, aiming to address a major public health threat with high morbidity, mortality, and healthcare costs, particularly in adults over 50.

• The updated C. diff vaccine formulation is designed for a two-dose regimen to improve completion rates and patient protection.

C. difficile Infection Overview and Public Health Impact

• C. difficile infection (CDI) is a significant healthcare-associated threat, causing nearly 500,000 annual infections in the U.S., with highest risk in those 65+ and individuals exposed to healthcare settings or antibiotics.

• Individuals on antibiotics or recently hospitalized are 7-10 times more likely to contract CDI.

• One in eleven people over 65 diagnosed with healthcare-associated CDI die within one month.

• Estimated annual U.S. healthcare costs for CDI are $5-6 billion.

• The CDC classifies C. diff as an urgent public health threat, with no vaccine currently available to prevent primary or recurrent CDI.

Clinical Development and Trial Results

• The first-generation C. diff vaccine underwent a Phase 3 CLOVER study with over 17,500 adults at increased risk; it showed robust antibody responses and was well tolerated but missed the primary endpoint.

• Secondary analyses from CLOVER indicated 100% efficacy against medically attended CDI and CDI requiring antibiotic intervention, and a 75% reduction in median CDI duration.

• The updated vaccine formulation, incorporating adjuvants, is in Phase 2 trials, with data expected in 2025 and a potential Phase 3 start in late 2025.

• Three updated formulations were evaluated; the preferred two-dose regimen is now in Phase 2.