How vaccines work?
- Traditionally, vaccines usually contain a weakened or dead form of the virus or bacteria.
- By injecting this vaccine into our body, it allows our immune system to recognise and create immune cells to fight against them.
- During a real infection, our immune system would recognise the viruses immediately and mount an attack to kill them thereby preventing a full blown infection.
Introducing the Messenger RNA vaccines
- The two new messenger RNA vaccine created by Pfizer-BioNtech and Moderna are novel and different from the traditional vaccines.
- The vaccines do not contain any COVID-19 virus - instead, it contains a genetical code called messenger RNA.
- The COVID-19 virus looks like a sphere with protein spikes on its surface. The messenger RNA codes for those protein spikes.
- The Messenger RNA contained within the vaccine will travel and enter our body cells after its injected into our muscle.
- Once inside our cells - the messenger RNA provides the instruction manual that allows our protein production factory within the cell to produce multiple copies of these spike proteins.
- When these spikes have been created and released - our immune system will now recognise these spikes and create antibodies against the spikes.
- The messenger RNA in the vaccine will then be destroyed within hours to days after its done its work.
How effective are these vaccines?
- The vaccine has been studied in people 16 years old and above with 95% effectiveness in preventing symptomatic COVID-19 infection from 7 days after 2nd dose of vaccine.
- 2 doses of the vaccine injected 21 days apart are required.
- The vaccine from Moderna has been studied in people 18 years old and above with 94% efficacy in preventing symptomatic COVID-19 infection from 14 days after 2nd dose of vaccine.
- 2 doses are required 28 days apart.
Its not known if either vaccine prevents asymptomatic infection with COVID-19, it is also not known also if people vaccinated can transmit the viruses to others.
Common Side Effects
- Injection site pain, fatigue, headache, muscle and joint pain.
- Some people in the trials reported fever - about 14% ( 1 in 7 ) of people developed fever after receiving the vaccine.
- Allergy to the vaccine - patients may get rash or eye swelling or even airway swelling due to the vaccine.
- Side effects are more common after the second dose
Who might not be suitable?
- The vaccines have not been studied in children less than 16 and pregnant ladies as of the time of production of this article. So the vaccines are not for people who fall into this two group.
- If you are breastfeeding, you should stop breast feeding for 1 week .
- If you are trying to have a baby, you should defer the conception during the vaccination period and for at least 1 month after the 2nd dose.
Are these Vaccines the solution to the pandemic?
- The vaccines gives 95% protection, there is still have a 5% chance of catching the COVID-19 infection.
- There is still a possibility that you could be an asymptomatic carrier of the virus and transmit the virus to others despite receiving the vaccine.
- If everyone else around you receives the vaccine together with you, then the risk of you actually catching the virus from them is very much reduced.
- It would take time as the vaccine is being produced and distributed worldwide.
- So in the meantime , there is still a need for mask wearing and social distancing for now to reduce your chance of catching the virus.
By : Dr Chen Yiming
Family Physician, MBBS (Singapore), GDFM (NUS), GDFP Dermatology (NUS)