Why is the eye drop vaccine usually more effective than the drinking vaccine?

1. Direct route to the Harderian gland

When the vaccine is instilled into the chicken's eye as a drop, it reaches the Harderian gland very quickly.

This gland is full of immune cells (lymphocytes and plasma cells), so direct and strong stimulation is performed.

2. Creation of local + general immunity

The eye drop creates both local immunity (IgA in the eye and respiratory tract) and systemic immunity (antibodies in the blood).

The drinking vaccine acts more through the intestine and has less focus on the respiratory tract.

3. Accurate and uniform dosage

In the eye drop, each chicken receives a full dose of vaccine.

In the drinking water, some chickens may eat less or more, or not eat at all → as a result, the uniformity of vaccination is reduced.

4. Faster effect

Because immune stimulation through the hardin gland begins immediately, the eye vaccine usually provides immunity faster.

5. Less sensitivity to environmental conditions

The vaccine in drinking water may be degraded by water quality (pH, chlorine, water hardness) or drug residues.

But in eye drops, the vaccine enters the chicken's body directly and is less degraded.