-
Asked by Ciano2019 to Katie on 13 Nov 2019.
-
Katie Fala answered on 13 Nov 2019:
Interesting question! In short, it depends on the vaccine. In the old days if you ever read about Edward Jenner and his smallpox trials, that was the only way that people knew to build immunity to the microorganisms that cause diseases. Nowadays there is a lot of clever technology – for example, vaccines for whooping cough, Pneumococcal/Meningococcal disease, Hib, HPV don’t have a whole bacteria/virus in them at all. Scientists determined the form of protein or sugar on the surface of the microbes that triggers our body to make antibodies and that is what is included in the injection. This works well for some disease-causing microbes, but not all, so some vaccines contain dead or extremely weakened bacteria – again, your body recognises those proteins and sugars that form the outer coat of these bacteria/viruses and starts to make antibodies so that you can fight off the infection if you were ever exposed to the wild-form of that bacteria. Examples of these vaccines include those for measles, mumps and rubella as well as the chickenpox vaccine. Let me know if you have any more questions about this!
-
Comments
Ciano2019 commented on :
Thanks Katie. Just one more thing how do they test these vaccines. Do they test them on people?
Katie commented on :
Sorry I’m only getting around to replying now! Yes, before being released on the market a new vaccine is tested. Initial lab testing must be passed first to show that the vaccine is safe and effective (this involves testing the vaccine on individual cells (‘in vitro’) or animals (‘in vivo’). Then clinical trials can begin, first with small groups of volunteers (this is called Phase 1) to check for major side effects in humans, then Phase 2 is a bit bigger and checks that the vaccine is achieving its’ purpose (making our body generate antibodies against the bacteria/virus) and works out the best dose/combo. Phase 3 is bigger again, well into the thousands of participants, and lets us get enough data to figure out how effective the vaccine is and estimate how much of the disease can be prevented by introducing the vaccine into the population. Also, because it involves so many people it is possible to check and find any particularly rare side effect that might not have shown up in Phase 1 and 2. If the data shows that the new vaccine is overall safe, effective and can significantly reduce the amount of that disease circulating in a given population, it can be licensed and introduced into the market. Phase 4 is the final phase, after the vaccine has been released to market the manufacturers have to keep following up and gathering data on efficacy and possible side effects. Hope that answered your question!