Live-attenuated vaccines stimulate a strong and effective immune response that is long-lasting. Given pathogens are<unk> , it is extremely rare for pathogens to revert to their pathogenic form and subsequently cause disease. Additionally, within the five WHO-recommended live<unk> s (tuberculosis, oral polio, measles, rotavirus, and yellow fever) severe adverse reactions are extremely rare. However, similar to any medication or procedure, no vaccine can be 100% safe or effective. Individuals with compromised immune systems (e.g., HIV-infection, chemotherapy, combined immunodeficiencies) typically should not receive live-attenuated vaccines as they may not be able to produce an adequate and safe immune response. Household contacts of immunodeficient individuals are still able to receive most<unk> s since there is no increased risk of infection transmission, with the exception being the oral polio vaccine. As precaution, live-attenuated vaccines are not typically administered during pregnancy. This is due to the risk of transmission of virus between mother and fetus. In particular, the varicella and yellow fever vaccines have been shown to have adverse effects on fetuses and nursing babies. Some live<unk> s have additional common, mild adverse effects due to their administration route. For example, the live<unk>  influenza vaccine is given nasally and is associated with nasal congestion. Compared to inactivated vaccines, live-attenuated vaccines are more prone to immunization errors as they must be kept under strict conditions during the cold chain and carefully prepared (e.g., during reconstitution).
Attenuated vaccine
Conjugate vaccine
Heterologous vaccine
Inactivated vaccine
Synthetic vaccine
Subunit vaccine
Plant expressed vaccine
Genetically modified vaccine