What sort of vaccine might mean the end of COVID-19?

AS EVERYONE knows, there is work going on around the world to find a vaccine to prevent COVID-19. As I mentioned last week, research to develop new drugs is also going on, along with work to re-purpose known drugs already used in other conditions. Yet a vaccine is perhaps the best hope for ending the pandemic.

Scientists are not starting from scratch, since previous research on acute respiratory syndrome severe, SARS and Middle East respiratory syndrome, MERS vaccines, has already opened up avenues of research.

In previous articles I said that the virus resembles a

World War Two floating mine. The spikes on the virus, which let it break its way into a cell, are called S protein. A vaccine targeting this protein could stop it getting into the cell and reproducing myriad copies of itself.

There are different types of vaccines. Live vaccines use a weakened form of the infecting organism that causes a disease. We call this an attenuated vaccine, because its ability to actually produce disease is weakened. It works by stimulating an immune response without causing disease. Measles, rubella and mumps are examples of live vaccines.

Inactivated vaccines use a killed version of the infecting organism so it is inactive.

This also causes an immune response but not infection. Inactivated vaccines are used to prevent influenza, hepatitis A and rabies.

These may not give as much protection as a live vaccine. So inactivated vaccines often need multiple doses, followed by booster doses later on, to provide long lasting immunity.

A newer approach could be to produce a genetically engineered vaccine, using genetically engineered RNA or DNA that has instructions for making copies of the S protein.

These copies would prompt an immune response to the virus.

This would theoretically be a safer way of developing a vaccine, since the active virus would not need to be handled.

However, no genetically engineered vaccines have yet been licensed for human use, although they are being researched. If a vaccine is developed, it will take time to produce and distribute.

Also, since people have no immunity to COVID-19, it’s likely that two vaccinations will be needed, three to four weeks apart.

People would likely start to achieve immunity to COVID-19 one to two weeks after the second vaccination