Attenuated simply means "weakened". An attenuated flu vaccine refers to vaccines made with live viruses (so you get a good immune response), but they have been weakened chemically so that they are unable to give you the flu.
There are two types of flu vaccines available in the US. What is called inactivated, inactive or "dead" vaccine and what is called "live", weakened/attenuated vaccine. The injectable vaccines (intradermal and intramuscular) are made with "dead" viruses and the nasal spray is made with "live" attenuated viruses.
They are called live attenuated vaccines. Attenuated means weakened. The nasal mist flu vaccine is an example of a live attenuated vaccine. The vaccines for flu that are injected are made from pieces of viruses or "dead" viruses. See the related question below for more information on these two types of vaccines.
Live attenuated influenza vaccine (LAIV) is a type of influenza vaccine in the form of a nasal spray that used to be recommended to prevent influenza.
Typically the flu vaccine is trivalent, with three strains.
They are called attenuated vaccines. Attenuated means weakened, they do this usually with chemicals and then the attenuated viruses are not able to make you sick, but they are strong enough to trigger the immune response to provide immunity.An attenuated virus. Attenuated simply means weakened. For example, you will see references to this in regard to the flu vaccines. This is also abbreviated when talking about the flu vaccines as LAIV, Live Attenuated Influenza Vaccine.That is a good description of what a vaccine is, although some other substances also could be described similarly. The weakened or killed virus in a vaccine is non-threatening to most people. It can be a problem for infants under six months old, some children and adults with under-developed immune systems or who have immune system disorders.
B.C.G Vaccine
No, in the US the injection forms of the vaccines are made from inactivated "dead" virus. The nasal spray vaccine contains weakened virus that can not make you get the flu but is called a Live Attenuated Influenza Vaccine (LAIV). There is a new form of injected vaccine for the flu in the 2011-2012 flu season in the US that is intradermal instead of the intramuscular route, it also contains inactivated virus particles. See the related question below.
Attenuated whole-agent vaccine
In the US, that would be the vaccine used in the H1N1/09 nasal spray vaccinations. These weakened viruses used to make that nasal vaccine are called attenuated, which means weakened. The weakening is usually done with chemicals. People aged 2 to 49 can use this nasal spray vaccine. Those younger or older should use the flu shots which are made with inactivated ("dead") viruses.
They are vaccines that contain viruses that have been treated to make them too weak to make you sick. The word "attenuated" just means "weakened". This type of live attenuated vaccine is what is approved for intra-nasal administration (nasal spray) of the flu vaccines in the US. The approved intra-muscular injection vaccine is made with totally inactivated ("dead") virus particles. See related questions below.
interval- flu vaccine and the shingles vaccine
Attenuated simply means "weakened". Vaccines made with attenuated pathogens, such as the flu virus in flu nasal mist vaccines in the US, work like any vaccine to trigger an immune response so that your body builds up antibodies to be immune to the virus (or whatever pathogen is intended to be prevented). Flu vaccines made for injection, for example, are made with inactive viruses that are either "dead" or are pieces of the virus that are incomplete so they can not cause disease but can trigger the proper immune response and antibody development. Other vaccines, like the flu nasal mist, use whole, "live" viruses in the vaccine preparation to get a better response and, in those vaccinations, the live viruses are weakened so that they can not make you ill but can cause the proper immunity to be developed.See the related questions below for more detailed information.
The vaccine is given through mouth because it is a live attenuated virus vaccine.