When do respiratory pathogen infections like Infectious Coryza peak in brown layers, and when is the ideal window for preventative vaccination?

Infectious Coryza, caused by the bacterium Avibacterium paragallinarum, is a highly contagious respiratory infection characterized by severe facial swelling, nasal discharge, and a devastating 10% to 40% drop in egg production. In Pakistan, Coryza outbreaks peak sharply during seasonal weather transitions in autumn (October to November) and early winter, when ventilation is restricted to keep birds warm, causing poor air quality and high humidity. To establish high-titer protection before lay, rearing brown pullets must be vaccinated with inactivated Coryza bacterins twice during the rearing phase: first at 6 to 8 weeks of age, followed by a crucial booster dose at 12 to 14 weeks. Vaccinating after 16 weeks of age is less effective and can trigger post-vaccinal stress as laying approaches. Disease pathology is detailed in the Poultry Encyclopedia, premium multi-strain inactivated Coryza vaccines are sold on Poultry Plaza, poultry mandi rate trends are updated daily on Poultry Rates, and healthy brown pullet flocks are listed on Murghi Mandi.