As the world braces for the H1N1 flu pandemic, citizens are reading themselves to receive the H1N1 flu vaccine to protect against an infection of this new fast-spreading flu virus. Currently, there are two types of delivery methods of the influenza vaccines available; the live attenuated virus vaccine which is administered via a nasal spray and the inactivated vaccine which is delivered by a shot intramuscularly. Researchers are also working on a new deliver method where a DNA based vaccine is delivered through the skin.
Inactivated Virus Vaccine Given as a Shot
This delivery method uses a vaccine that contains the dead influenza viruses. The virus’s structure is intact but it has been killed and is therefore incapable of causing an infection. Introducing the vaccine via an intramuscular injection allows the virus to enter the body and elicit an immune response. The body produces antibodies against virus in preparation for an active exposure. Some individuals develop some mild flu like symptoms associated with the vaccination and other may develop a sore spot where the needle was inserted.
Live Attenuated Vaccine Given as Nasal Spray (FluMist)
The vaccine (LAIV) contains the live influenza virus in an attenuated or weakened form; the virulent portion removed or inactivated. The attenuated virus is also temperature sensitive and will not replicate at the temperatures found in the lungs but will replicates in the nasal mucosal membranes. This vaccine is administered as a nasal spray. In the nasal membranes the virus replicates but once in the lungs it is unable to replicate. It however can elicit an immune response in the body. Vaccinated individuals may develop mild flu like symptoms. There is also an off chance that the attenuated virus may be transmitted from person to person.
Epidermal DNA Based Vaccine
Epidermal DNA vaccines are considered the future of flu shots. DNA based vaccines use only portions of DNA in the form of a DNA plasmid. The plasmids once in the body direct and trigger the desired or preprogrammed immune response. In this case the vaccine is administered through the skin; it is propelled into the skin using microscopic gold particles at a high velocity. The vaccine has already been tested on humans with positive results (Drape RJ, Macklin MD, Barr LJ, Jones S, Haynes JR, Dean HJ “Epidermal DNA vaccine for influenza is immunogenic in humans” Vaccine. 2006 May 22;24(21):4475-81). This delivery method is non-invasive as the vaccine is in the form of a dry powder. The mixture is accelerated using helium gas and once up to speed the mixture penetrates the skin. The main advantages of this new vaccine is that it does not for one, require eggs to replicate the virus, which is the rate limiting step in flu virus production nor does it make the recipient sick.
The idea of painless, less invasive vaccines against influenza is promising. The DNA technology gives scientists the ability to develop DNA plasmids quickly as new virus strains appear or as old virus strains mutate. This method also translates to rapid manufacturing of vaccines since the production process is not limited by the availability of chicken eggs. The DNA based vaccines contain no viruses and therefore is no chance that they will cause an infection.
