Tips for Successful Vaccination • If a vaccine is mishandled or improperly used, it may result in vaccination failure. All vaccines are labeled with instructions for use and expiration dates. If the entire flock is not vaccinated properly, the disease may spread. • Newly hatched chicks have some passive immunity passed from the mother through the egg. Vaccination of chicks at less than 10 days of age often does not produce uniform or lasting immunity. An exception is the vaccination for Marek's disease, which is ordinarily given on the day of hatch. • Rotate vaccine stock, as vaccines can deteriorate over time. Vaccines come with a date of expiration. Any outdated product should be discarded. • Each vaccine is designed for a specific route of administration. Use only the recommended route. • Do not vaccinate sick birds (except in outbreaks of laryngotracheitis or fowl pox). • Protect vaccines from heat and direct sunlight. • Most vaccines are living, disease-producing agents. Handle them with care. • When using the drinking-water method of vaccination, be sure the water is free of sanitizers and chlorine. Live-virus vaccines are readily destroyed by these chemicals. • After vaccinating, burn or disinfect all opened containers to prevent accidental spread to other poultry.