How are COVID-19 vaccines developed?

This article was published on
June 8, 2021

This explainer is more than 90 days old. Some of the information might be out of date or no longer relevant. Browse our homepage for up to date content or request information about a specific topic from our team of scientists.

There are various potential approaches to developing a Covid-19 vaccine, as Professor Walter Jaoko explains.

There are various potential approaches to developing a Covid-19 vaccine, as Professor Walter Jaoko explains.


What our experts say

Prof. Walter Jaoko

Professor of medical microbiology and tropical medicine, Director KAVI Institute of Clinical Research, University of Nairobi

There are different ways of developing vaccines. You can weaken a virus, so it is still alive but is weakened, that is what we call attenuation. Therefore, it cannot cause [severe] disease in an [otherwise healthy] human being. When somebody is given the vaccine, the body stimulates responses thinking that it has become infected and those antibodies and cells are, therefore, ready in the event that you face the real virus.

Secondly, you can take just the portion of the virus, what we call the spike protein, and develop a vaccine out of it. So, when the body sees that spike protein, it thinks it has seen the virus and therefore produces responses to fight it either [by producing] antibodies or [activating] white blood cells.

The third way of making a vaccine, and this is what is being used largely in Africa, is called a vectored vaccine, where you take  [a part of the spike protein's gene] and you put it into a vector, which is [another] virus that [has been modified so it] does not cause infection in human beings. [This genetic code gets used by the host to produce the piece of spike protein, which is then transported to the surface of the cell]. That makes the body recognize that [spike protein] much faster and in a robust way.

The final one, which we still don’t have in Africa but few countries are using it, is a new technology called the messenger RNA technology. This is what is used in some vaccines like Moderna and Pfizer vaccines, where you take the message that the virus uses to prepare spike protein and that is what [goes into the patient]. The human cells [take it up and] read that message, prepare the spike protein on their surface and then the same human being’s immune response recognizes that protein and therefore produces antibodies and white blood cells to fight the COVID virus. So, the body is therefore protected that way.


Context and background


Media briefing

Media Release

This explainer was created from a media briefing presentation. You can access the full media briefing here.

Expert Comments: 

No items found.


No items found.