system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Influenza pandemic is mainly caused by-
assistant
The correct answer is  All known pandemics caused by influenza A strains. Ref:PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 23rd edition , Page: 153