Vaccines work by introducing a weakened or inactivated form of a pathogen into the body, stimulating the immune system to produce antibodies and memory cells that protect against future infection.

Live attenuated vaccines contain a weakened form of the pathogen that is still capable of replicating, but not causing disease. Examples include vaccines for measles, mumps, and rubella (MMR).

Inactivated vaccines contain pathogens that have been killed using heat, chemicals, or radiation. Examples include vaccines for polio, hepatitis A, and rabies.

Subunit vaccines contain purified components of the pathogen, such as proteins or polysaccharides. Examples include vaccines for hepatitis B, whooping cough, and human papillomavirus (HPV).

Toxoid vaccines contain inactivated bacterial toxins, which stimulate the immune system to produce antibodies that neutralize the toxins. Examples include vaccines for diphtheria and tetanus.

Active immunization stimulates the immune system to produce its own antibodies, while passive immunization provides temporary protection by introducing antibodies from another source.

Vaccines can stimulate both humoral immunity (production of antibodies) and cell-mediated immunity (activation of T cells) to provide protection against pathogens.

Herd immunity occurs when a large proportion of a population is vaccinated, reducing the likelihood of an outbreak and protecting both vaccinated and unvaccinated individuals.

The MMR vaccine is a combination vaccine that protects against measles, mumps, and rubella. It is typically given in two doses, the first at 12-15 months of age and the second at 4-6 years of age.

The Centers for Disease Control and Prevention (CDC) publishes a recommended vaccination schedule for children in the United States, which includes vaccines for diseases such as measles, mumps, rubella, polio, and hepatitis B.

Maintaining up-to-date vaccination records is important for ensuring timely administration of booster doses, tracking vaccine coverage in a population, and facilitating international travel, where proof of vaccination may be required.

The HPV vaccine protects against human papillomavirus (HPV), which is the leading cause of cervical cancer. It is typically given in two or three doses, depending on the age of the recipient.

The Centers for Disease Control and Prevention (CDC) publishes a recommended vaccination schedule for adults in the United States, which includes vaccines for diseases such as tetanus, diphtheria, pertussis, measles, mumps, rubella, and influenza.

Vaccine safety monitoring is important for detecting and investigating adverse events following immunization, ensuring the quality and effectiveness of vaccines, and tracking vaccine coverage in a population.

Public health agencies play a crucial role in vaccine distribution and administration by procuring and distributing vaccines, providing vaccination services to the public, and educating the public about vaccines and immunization.