Safety and stability
Since LAVs contain living organisms, there is a degree of unpredictability raising some safety and stability concerns.
- Attenuated pathogens have the very rare potential to revert to a pathogenic form and cause disease in vaccines or their contacts. Example for this are very rare, serious adverse events of:
- Vaccine-associated paralytic poliomyelitis (VAPP) and
- Disease-causing vaccine-derived poliovirus associated with oral polio vaccine (OPV)
- Functional immune systems eliminate attenuated pathogens in their immune response. Individuals with compromised immune systems, such as HIV-infected patients may not be able to respond adequately to the attenuated antigens.
- Sustained infection, for example tuberculosis (BCG) vaccination can result in local lymphadenitis or a disseminated infection
- If the vaccine is grown in a contaminated tissue culture it can be contaminated by other viruses (e.g. retrovirus with measles vaccine)