Different types of COVID-19 vaccines: How they work

The COVID-19 vaccines have received doubt and skepticism. One of the main reasons was how quickly it took to develop them, thus, lacking the time to properly test for side-effects, compared to their other vaccine counterparts. This fallacy is further strengthened with news reports of various deaths and complications that occurred after receiving the vaccine.

While it is true that cases of myocarditis and pericarditis youth have been reported more frequently after getting the second dose of one of the two mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna), these reports are rare and “the potential benefits or COVID-19 vaccination outweigh the known and potential risks, including the possible risk of myocarditis or pericarditis” reported by the Center of Disease Control and Prevention (CDC). Hence, in order to disprove some of the claims and provide more information on the vaccines, here is an objective report of vaccines that are approved by the CDC.

Just a disclaimer, all vaccines are safe, effective and reduce your risk of severe illness if you contract COVID-19 virus. The CDC also does not recommend one vaccine over another.


Pfizer-BioNTech is applicable for those who are 12 years and older.

You will receive 2 shots 21 days apart, and you will be fully vaccinated 2 weeks after your second shot.

According to the CDC, the Pfizer-BioNTech (COMIRNATY) vaccine was 95% effective at preventing laboratory-confirmed infection with the virus that causes COVID-19 in people who received two doses and had no evidence of being previously infected


Next, Moderna is applicable for those who are 18 years and older.

You will be given 2 shots 28 days apart and you will be fully vaccinated 2 weeks after your second shot

Johnson & Johnson’s Janssen

Johnson & Johnson’s Janssen is eligible for those who are 18 years and older.

In comparison to Pfizer-BioNTech and Moderna, you will only need one shot, although it will still take you 2 weeks to be fully vaccinated after your shot.

Third dose and booster shots

Third dose and booster shots are given to those who have weakened immune systems, thus undermining the effectiveness of the first two shots, and for those whose effects of the first two doses have worn off respectively.  

However, Pfizer CEO Albert Bourla said everyone will “likely” need a booster dose of a Covid-19 vaccine within 12 months of getting fully vaccinated. (Lovelace, 2021)

Important things to note

Do note that the aforementioned vaccines, i.e. Pfizer-BioNTech, Moderna and Johnson & Johnson/ Janssen are not the only vaccines that are available. These are just approved and authorized vaccines in the United States. It is important to be aware of the other brands of vaccines your respective countries have approved of and are using.

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