Rather, it begins with the long history of infectious disease in humans, and in particular, with early uses of smallpox material to provide immunity to that disease. Evidence exists that the Chinese employed smallpox inoculation or variolation, as such use of smallpox material was called as early as CE. It was practiced in Africa and Turkey as well, before it spread to Europe and the Americas.
His method underwent medical and technological changes over the next years, and eventually resulted in the eradication of smallpox.
And then, at the dawn of bacteriology, developments rapidly followed. Antitoxins and vaccines against diphtheria, tetanus, anthrax, cholera, plague, typhoid, tuberculosis, and more were developed through the s. The middle of the 20 th century was an active time for vaccine research and development. Inactivated vaccines use viruses whose genetic material has been destroyed so they cannot replicate, but can still trigger an immune response.
Both types use well-established technology and pathways for regulatory approval, but live attenuated ones may risk causing disease in people with weak immune systems and often require careful cold storage, making their use more challenging in low-resource countries.
Inactivated virus vaccines can be given to people with compromised immune systems but might also need cold storage. Subunit vaccines use pieces of the pathogen - often fragments of protein - to trigger an immune response.
Doing so minimises the risk of side effects, but it also means the immune response may be weaker. This is why they often require adjuvants, to help boost the immune response. An example of an existing subunit vaccine is the hepatitis B vaccine. Nucleic acid vaccines use genetic material — either RNA or DNA — to provide cells with the instructions to make the antigen.
Once this genetic material gets into human cells, it uses our cells' protein factories to make the antigen that will trigger an immune response. The advantages of such vaccines are that they are easy to make, and cheap. Since the antigen is produced inside our own cells and in large quantities, the immune reaction should be strong. A downside, however, is that so far, no DNA or RNA vaccines have been licensed for human use, which may cause more hurdles with regulatory approval.
To clarify the landscape for our readers, our vaccine tracker has been split in two. The first chart details vaccine candidates that are still in development to address the lack of vaccines and access in many countries around the world; the second chart lists vaccines that are authorized or approved by one or more country. Our charts are updated every other week.
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