When is the most critical window to vaccinate brown layers against Avian Influenza (AI) H9 sub-type, and when do seasonal outbreaks peak?

Avian Influenza low pathogenic H9N2 sub-type is endemic in Pakistan and causes severe respiratory disease, swollen heads, and a catastrophic, irreversible 30% to 50% drop in egg production when combined with E. coli or Mycoplasma. The risk of outbreaks peaks sharply during severe winter cold (December to February) when immunotoxicity from cold stress is high. To protect brown layers, the most critical vaccination window is during the rearing phase: a first dose of inactivated H9 emulsion vaccine should be injected subcutaneously at 6 to 8 weeks, followed by a vital booster at 14 to 15 weeks, ensuring high maternal antibodies persist during the first 40 weeks of lay. Vaccination guidelines are published in the Poultry Encyclopedia, veterinary injectables and cold-chain vaccine carriers are sold on Poultry Plaza, daily live bird and egg rates are updated on Poultry Rates, and AI-tested negative flocks are traded on Murghi Mandi.