The following is a very good article on how Pfizer’s and Moderna’s vaccines were developed.
Politics, Science and the Remarkable Race for a Coronavirus Vaccine
https://www.nytimes.com/2020/11/21/...tion=click&module=Top Stories&pgtype=Homepage
There has been some discussion that these vaccines couldn’t be safe and effective because it takes years to develop a vaccine. However, the following passage makes clear that this isn’t the case anymore:
”Unlike the older, slower ways of developing vaccines, which involve stimulating the bodies immune system by injecting inactivated or weakened viruses, Moderna and other companies created platforms that work like the operating system on a computer, allowing researchers to quickly insert new genetic code from a virus — like creating an app — and create a new vaccine.
The method employs a synthetic form of a genetic molecule called messenger RNA, or mRNA, to cause human cells to make a harmless viral proteins called a spike, which then stimulates the immune system to make antibodies and immune cells that can recognize the spike quickly and counterattack when needed.
Earlier efforts test new types of vaccines on outbreaks like SARS, MERS and Zika had fizzled when the threat from those viruses receded, before large clinical trials could be carried out. But the outbreak spreading in China had the hallmark of a prolong pandemic, a tragedy but also a proper testing ground for the new bio technology.”
The comments to the article are also worth taking a look at.