Monitoring Vaccine Safety: COVID-19 Cohort Event Monitoring Study

Project Type: Prospective Cohort Study
Focus Area: Adverse Event Monitoring for COVID-19 Vaccines

Ciheb-Kenya, in partnership with stakeholders, conducted a Cohort Event Monitoring (CEM) study to assess the safety profile of COVID-19 vaccines in real-world use. The goal was to identify the incidence, severity, and patterns of adverse events following immunization among vaccine recipients in Kenya.

Study Overview

  • Target sample size: 17,000 participants

  • Enrolled: 9,288 participants

  • Study focused on individuals who received approved COVID-19 vaccines under the national rollout.

Vaccine Distribution among Participants

  • Janssen (J&J): 55.6%

  • Pfizer (Grey Cap): 44.2%

  • Pfizer (Purple Cap): 0.2%

Adverse Event Reporting

  • A total of 6,265 adverse events were reported from 2,987 participants (approximately 32% of those enrolled).

  • These events were assessed using MedDRA—a standardized global medical terminology used to classify and analyze adverse events by:

    • System Organ Class (SOC)

    • High-Level Group Term (HLGT)

    • High-Level Term (HLT)

    • Preferred Term (PT)

    • Lowest Level Term (LLT)

Current Status

  • Data analysis and reporting have been completed.

  • A manuscript is currently under peer review, with findings set to inform future vaccine safety policy and practice.