Vakcina

A vakcina is a medical preparation designed to provoke an immune response against a specific infectious disease, with the aim of providing active immunity. Vaccines typically present an antigen from a pathogen, a harmless form of the pathogen, or genetic material that encodes an antigen. This exposure trains the immune system to recognize and respond more effectively to future encounters with the real pathogen, reducing the risk of illness or its severity.

There are several vaccine types. Live attenuated vaccines use weakened forms of the pathogen; inactivated vaccines use killed organisms; subunit, toxoid, and conjugate vaccines include specific proteins or polysaccharides from the pathogen; and newer platforms include messenger RNA (mRNA) vaccines and viral-vector vaccines. Some vaccines rely on DNA or other technologies to deliver instructions for making antigens inside the body.

Vaccines undergo development and regulation through preclinical studies and phased clinical trials to assess safety and efficacy. After regulatory approval, they are monitored through post-marketing surveillance to detect rare adverse events. Common side effects are typically mild, such as soreness at the injection site or fever; serious reactions are rare and continuously monitored.

Public health use of vaccines has led to substantial reductions in many infectious diseases and, in some cases, near-elimination. Effective vaccination programs depend on high coverage, proper storage and handling (the cold chain), and ongoing safety monitoring. The term vakcina derives from historical usage related to cowpox and the origin of the concept of vaccination.