What method is used for administering smaller vaccine doses in infants?

Administering smaller vaccine doses in infants is typically done intramuscularly. This method allows for the appropriate absorption of the vaccine into the muscle tissue, which can handle the smaller volume of the vaccine and is effective for the immune response. Intramuscular administration is preferred for many vaccines due to its ability to elicit a stronger immune response and provide adequate coverage against diseases.

In infants, sites such as the thigh are commonly used for intramuscular injections, as they are well-developed and can accommodate the necessary dose without posing risks associated with injection into smaller or less developed muscles. This route is crucial for ensuring the vaccine's efficacy and stimulating an appropriate immune response, which is vital in protecting infants who are more vulnerable to infections.

Other methods like intravenous administration are generally not used for vaccines due to the risk of complications and the need for careful monitoring, subcutaneous injections are typically reserved for specific vaccinations and are not the first choice for infant vaccines, and topical application is unsuitable for vaccines as it does not achieve the desired systemic immune response.