The Different Types of Covid-19 Vaccines, Explained

How different companies are approaching the development of a new Covid-19 vaccine

5 min readDec 7, 2020


In the 1760s — as smallpox was killing nearly 400,000 Europeans each year — a strange rumor started to spread: Dairy workers never seemed to contract smallpox.

This rumor reached a surgeon’s apprentice named Edward Jenner, who recognized that dairy workers had already been exposed to a similar virus called cowpox. Jenner started to inoculate children with cowpox, and the world’s first vaccination was born.

The principle behind Jenner’s approach — using a weaker version of a virus to create immunity to the more deadly version — is still used in some vaccines. But today there are many other methods for vaccine production, and these are being used to create new Covid-19 vaccines in record time.

Vaccine type #1: Live attenuated

The word “attenuated” means “reduced in force” or “weakened.” So, live attenuated vaccines contain an active but weakened version of the virus (this is similar to the idea used in the first smallpox vaccines).

Pros: Very effective; can provide a lifetime of protection with a single shot.
Cons: Doctors may not advise them for people with especially weak immune systems.

Live attenuated vaccines already in use: measles, mumps, and rubella (MMR), chickenpox, rotavirus, smallpox, yellow fever.

Companies developing live attenuated Covid-19 vaccines: Codagenix, Indian Immunologicals Ltd.

Vaccine type #2: Inactivated

Inactivated vaccines contain a virus that has been killed (usually by heat or chemicals during the production process).

Pros: Very safe, even for people with unhealthy immune systems.
Cons: Often require booster shots because…



Medium Coronavirus Blog

Biology postdoc by day, graphic designer by night. Creator of “Data Worth Seeing.”