But an unanticipated difficulty in bulk production of the live attenuated virus
vaccine has slowed its progress.
Deacon maintains that scientists will need to prevent the attenuated virus
from permanently infecting people before it can be considered safe.
The oral live attenuated virus
vaccine is not recommended during pregnancy, except in cases of the prospective mother's continued, close exposure or travel to typhoid-endemic areas.
Live, attenuated virus
vaccines being developed by potential competitors have a small but real risk of causing severe, encephalitic West Nile disease.
In addition to the issue of freezer storage, other potential barriers cited by less than 10% of respondents included "concerns about safely administering a live attenuated virus
to patients with chronic medical conditions," and the "fact that vaccine will not be licensed for immunosuppressed patients.
The major advantages of live attenuated virus
vaccines are that they induce a more balanced immune response and that the resulting immunity is longer lasting than with killed vaccines or immune globulins (13-15).
These researchers have crumbled the orthodoxy that the only way to make an AIDS vaccine is with a live or attenuated virus
," says Schultz.
DNA vaccines are also noninfectious and inherently stable, and therefore, ideal to target diseases such as HIV, where inoculation with a dead or attenuated virus
is too risky.
Strategies that have been explored include immunization with purified coronavirus S glycoprotein or S glycoprotein epitope conjugates, with inactivated coronavirus, with live attenuated virus
, and with vaccine vectors carrying either full coronavirus genes or antigenic epitopes, he said.
Because vaccination with live attenuated virus
had been suspected of causing past deaths of African wild dogs (14,15) the animals in this breeding program were vaccinated with a CDV-ISCOM vaccine, which does not contain live virus.
Louis wanted to know if, in the close confines of a day care environment, the live, attenuated virus
used in a chicken pox vaccine (not yet on the market) could jump from a vaccinated child to a nonvaccinated child.
In early clinical trials,(5) a total of 4240 children 1 to 12 years of age received 1000-1625 PFU of attenuated virus
per dose of VARIVAX and have been followed for up to nine years post single-dose vaccination.
Ease of administration and stimulation of local immunity are among the potential attributes of the vaccine, which contains three live attenuated virus
strains in a large-particle mist that is administered by a nasal sprayer and is delivered to the mucosal surfaces where the influenza virus replicates.