vacunes

Vacunes are biological preparations that stimulate the immune system to develop protection against specific diseases. They provide active immunization and can prevent illness, reduce transmission, and contribute to herd immunity.

There are several types: inactivated or attenuated whole-pathogen vaccines; subunit, toxoid, and conjugate vaccines; nucleic acid vaccines such as mRNA; and viral-vector vaccines. Most vaccines require adjuvants to enhance the immune response and stabilizers to improve shelf life. Administration is usually intramuscular or subcutaneous, though oral and nasal vaccines exist.

Development and safety: vaccines undergo preclinical studies and phased clinical trials; regulatory bodies assess safety and effectiveness before approval. After introduction, pharmacovigilance monitors adverse events. Most vaccines have favorable safety profiles; common side effects are mild, such as soreness at the injection site or fever. Rare adverse events are investigated with ongoing risk-benefit assessment.

Impact and challenges: widespread vaccination has reduced incidence of many diseases and led to eradication of smallpox and near-elimination of polio in most regions. Challenges include maintaining cold chains, manufacturing capacity, cost, access disparities, and vaccine hesitancy. Public health programs and international initiatives work to improve coverage and equity.