I’m a microbiologist. I wash my hands often, I don’t eat canned green beans or any home-canned food (due to a horrible botulism example given in a bacteriology class), I don’t ask for antibiotics if I just have a cold, and I believe in vaccination programs.
Recently, due to the various controversies surrounding the H1N1 vaccine, and because I just gave permission for my children to be vaccinated at school, I have been thinking about vaccination rather a lot. Even though I believe absolutely in the benefits of vaccination, I also have the usual concerns when considering whether to accept a new vaccine for my children. So, when I read or hear sensational press coverage over emphasizing vaccination risks, I worry, and I want to hear a balanced viewpoint.
So I thought I would share what I have learned about the H1N1 vaccine.
- There are two H1N1 vaccine options, a live attenuated vaccine, delivered as a nasal spray, and a killed vaccine, delivered as an intramuscular injection.
- Live Attenuated Influenza Vaccine (LAIV) contains a living virus that is no longer capable of causing disease. Attenuation can occur as a result of passage in the laboratory, a process whereby virulence is lost after culture for many generations. Viruses can also be attenuated by genetic manipulation to disrupt virulence genes.
- The flu virus is cultured in chicken eggs. That’s why you get asked about albumen/egg allergies before you get the shot.
- The H1N1 vaccine strain in the nasal vaccine is also cold-adapted. It is cultured under successively decreasing temperatures, selecting for organisms that grow best below 25°C. This means that the virus in the vaccine will grow well in the colder temperature of the nasal passages and throat (good for eliciting an immune response at the site of viral entry), but will not grow in the (warmer) lower respiratory tract and cause disease.
- Because the nasal spray contains live virus, you can shed virus for 1-3 weeks after immunization. However, the virus is attenuated and cold-adapted, and so will not cause disease in healthy people. Because immunocompromized people may be at risk from attenuated viruses, contacts and caregivers of such individuals are recommended to get the flu shot, not the live attenuated vaccination.
- Studies on the safety and efficacy of live attenuated influenza vaccines have been conducted since the 1960’s. The H1N1 vaccine is prepared in the same way as the usual flu vaccines, the difference being that instead of a “cocktail” of viruses, like the normal seasonal flu vaccine, it contains only the H1N1 strain (is monovalent).
- The H1N1 flu shot contains killed H1N1 virus. This virus is not capable of multiplying within the body.
On the Urban Science Adventures blog there is good overview of the science behind vaccination. That blogger makes makes the following point:
I hope not to re-live the lessons of Flu epidemics of the past. Perhaps our society’s less-than-impressed attitude with vaccines is because unlike our grandparents and parents before them, we don’t know what it is like to lose scores of relatives and neighbors from communicable diseases like they did.
We all have to make choices for ourselves and our families, weighing the benefits and potential risks, and making decisions based on our own health situation and risk factors. We probably shouldn’t accept vaccines without asking good questions, but we also should be able to separate legitimate concerns from sensationalistic scare tactics. Let’s not forget the ultimate benefits of vaccination programs. If a vaccine had been available in 1918, the outcome would certainly have been different.
- Centers for Disease Control:2009 Influenza Vaccine Information
- Minnesote Department of Health: Information on the Live Attenuated Influenza Virus
- Medical News Today: Medimmune LAIV Clinical Trial Report
- More from Urban Science Adventures: H1N1 Vaccination Hysteria Part 2: Should I get the shot?.
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