An inactivated vaccine is different from a live attenuated vaccine. A live vaccine contains germs that have undergone some changes to remove most of their active components, but the virus is still alive. In contrast, the inactivated vaccine involves manipulation of the germ so it produces an immune response, but the germ or virus is killed chemically or with heat in the making of the vaccination. When vaccines are inactivated they cannot cause the illness against which they protect, whereas in live vaccines there is a remote chance, especially for those with immunosuppression, of contracting illnesses from the vaccine.
There are many inactivated vaccine forms available and millions of people receive them yearly. Vaccines like the flu shot, and one form of the poliovirus vaccine (Salk vaccine) stand as examples, as do shots such as the one vaccinating against the H1N1 virus. Vaccines that are inactivated don’t always contain viruses and instead may help provide protection against bacterial illnesses. Some examples include the vaccinations for pertussis (whooping cough), cholera, and typhoid.
It’s been shown that live attenuated immunizations may provide stronger protection because they produce a more significant immune response. For this reason, people who receive an inactivated vaccine often need additional shots to extend the immunity, but certain live virus vaccines require boosters as well. The length of time someone is protected from a disease when receiving an inactivated vaccine is variable and depends very much on the specific shot given. Flu vaccines are usually only thought effective for a year, but one of the reasons for this is that the vaccine is reformulated yearly to provide protection for the strains of flu immunologists believe will be most prevalent that particular year.
Some definite disadvantages exist when giving live vaccinations. Though most people will not suffer ill effects from them, a small number of people may not be able to receive them without encountering problems. If the immune system is weak from things like illness or use of drugs that cause compromise, there is a real, though unlikely, chance of getting ill from live virus exposure. This risk doesn’t occur with an inactivated vaccine, and providing vaccinations have been prepared properly, there is virtually no risk of getting an illness from a dead virus or bacteria.
Doctors often weigh when it is best to hazard risk of administering live virus vaccinations or when the environment is safe enough to switch to fully inactivated versions. In recent years, pediatricians have come to stronger agreement that in many parts of the world giving the live virus polio vaccine is no longer necessary. The chances of encountering this disease in most developed parts of the world are extremely remote.
Pediatrician guidelines now call for inactivated vaccine use for polio. They feel the shot and its boosters provide strong enough protection for children, whose chances of contracting polio are extremely minimal, in any case. In parts of the world where polio is still a problem, live polio vaccine is still preferred.