how do scientists create vaccines for different diseases and what is the name for the diseases name which was very hard

Question: how do scientists create vaccines for different diseases and what is the name for the diseases name which was very hard to find vaccine for ?
- Keywords:
  disease,
  health,
  vaccine
Asked by vaish to Martin M, Erin P, Christie, Bruno Silvester L on 8 Mar 2024.
- Erin Pallott answered on 8 Mar 2024:
  
  Vaccines are developed and created through the work of many scientists. First we need to know about the disease. Basic biology research will work on understanding what the disease is, how it progresses, how it infects the body and more.
  
  This knowledge is used to think about targets for a vaccine. What can we use to induce and immune response in the body, without making us sick? It is usually a part of, or an inactivated form of the pathogen.
  
  Then we can start creating the vaccine itself, which will contain the immune-activating component, and some other ingredients to ensure it is safe and can last long enough to be delivered to patients, and stimulates better immune responses.
  
  After all this research, its ready to be taken to clinical trials, where we test the safety in humans, starting with small numbers of healthy individuals. After passing the trials, it can be approved for wider use.
  
  There are still MANY diseases we haven’t got fully effective vaccines for. HIV is maybe the most deadly viral disease we don’t have a vaccine for (but we have other therapies to prevent transmission). The fact it hides within immune cells has made it very hard to target.
  
  Parasitic diseases have also been really hard to develop vaccines for. Malaria is a single-celled parasite with a complex life cycle and a very unusual genome. Worm parasites are also very complex, they’re multi-cellular animals with many more genes than a bacteria or virus. Soil-transmitted worms still infect over 1 billion people worldwide.
- Martin McCoustra answered on 8 Mar 2024:
  
  Perhaps the best was to explain this is to take an example… Smallpox is a terrible disease but has now been eliminated. In the 1760s a doctor called Edward Jenner recognised that people who had had a similar sounding disease but much less fatal disease, cow pox, didn’t get small pox. He assumed tested this out and found that giving someone cow pox prevented them getting small pox. This was the first example of a vaccine. The process is much the same today… we find a weak version of the disease carrier and use that to vaccinate people.
- Bruno Silvester Lopes answered on 10 Mar 2024:
  
  Martin has given a very excellent answer. I work in the area of infectious diseases. There are many bacteria and viruses that we find very difficult to find a suitable vaccination in order to treat them. Eg include Campylobacter bacteria that causes food poisoning and influenza virus that causes flu. It is because these bugs can manipulate themselves and escape our immune system. Hope this helps!
- Christie Waddington answered on 15 Mar 2024:
  
  It’s a long process! All vaccines have an active component (the antigen) which generates an immune response inside of our body. This antigen is normally a small part of the disease-containing organism e.g. a protein, or an inactive/weakened form of the whole organism.
  
  Each vaccine being developed has to go through screens and evaluation to determine which antigen is best to use for the vaccine. This is the pre-clinical phase and is not performed in humans. Normally it’s tested in the lab first, and then if it looks good it is first tested on animals.
  
  Then you have the clinical phases – there are 3. Phase I – small number of human volunteers. Does it work in humans? And is the dosage correct? Phase 2 – Few hundred human volunteers to further assess safety, whether it works, any side effects. There are normally multiple trials in this phase, and it is compared to a placebo (no vaccine given to volunteers). Phase 3 – vaccine is given to thousands of volunteers, and is usually a blind study (no one in the study knows who is given the vaccine and who is given the placebo). All the data is assessed (there’s a ton of regulations that that have to follow to make sure everything is ok, and they’re very strict!). Even when it’s released, the vaccine is still monitored to ensure it is still ok to use.
  
  Part of my job is to make the amount of vaccine/medical drug that the doctors need for each of the Phase 1/2/3 clinical trials. We take the gene sequence of the vaccine, express it in a cell line, grow it up (up to 20,000 L!) and purify it to it’s ok to go into the human volunteers (also have a ton of regulations and tests we have to abide by).
  
  There are a few diseases we can’t vaccine against, viruses are hard to vaccinate against as they can change so quickly (like the rhinovirus that causes the cold) although new technologies mean we might have a vaccine one day!