If the techniques used in both vaccines are similar and if both use the spike protein approach, then how is the mRNA vaccine more effective than the other ones and more importantly how come it is also effective towards the new variations of the virus such as the Delta variant whereas the others are not? The same protein should be built with the same mRNA, right? I am a little confused here.

  • $\begingroup$ The techniques used in mRNA vaccines and inactivated virus vaccines are not similar. Here's some info on inactivated virus vaccines at ScienceDirect: sciencedirect.com/topics/medicine-and-dentistry/… and here is info on the Covid mRNA vaccines at the CDC: cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/… $\endgroup$
    – Armand
    Jun 24, 2021 at 22:44
  • $\begingroup$ Re: "more importantly how come ..." is a different question and your premise is not quite correct. Here's a paper from a decade ago about SARS that discusses why the spike protein makes a good vaccine target in these viruses: Du, L., He, Y., Zhou, Y. et al. The spike protein of SARS-CoV — a target for vaccine and therapeutic development. Nat Rev Microbiol 7, 226–236 (2009). doi.org/10.1038/nrmicro2090 $\endgroup$
    – Armand
    Jun 24, 2021 at 22:49
  • $\begingroup$ I will definitely look more into those. Thank you! $\endgroup$
    – username
    Jun 25, 2021 at 10:19

1 Answer 1


In molecular biology, a ribonucleic acid vaccine or messenger RNA vaccine is a type of vaccine that uses a copy of a natural molecule called messenger RNA to produce an immune response. The vaccine transfects molecules of synthetic RNA into immunity cells.

An inactivated vaccine is a vaccine consisting of virus particles, bacteria, or other pathogens that have been grown in culture and then lose disease-producing capacity. In contrast, live vaccines use pathogens that are still alive. Pathogens for inactivated vaccines are grown under controlled conditions and are killed as a means to reduce infectivity and thus prevent infection from the vaccine. The virus is killed using a method such as heat or formaldehyde.

mRNA vaccines are a new type of vaccine to protect against infectious diseases. COVID-19 mRNA vaccines are given in the upper arm muscle. the cell displays the protein piece on its surface. Our immune systems recognize that the protein doesn’t belong there and begin building an immune response and making antibodies, like what happens in natural infection against COVID-19.

They do not affect or interact with our DNA in any way.

mRNA never enters the nucleus of the cell, which is where our DNA (genetic material) is kept.

For more info - mRNA and Inactivated (Killed Vaccine)

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    $\begingroup$ The mRNA vaccine doesn't transfect (much) into the immune cells directly, most is apparently into the muscle and vascular and lymphatic cells at the site of injection, then some transported around the body, ending up in the liver largely. Your later description is closer. You also have the links for mRNA and inactivated swapped. $\endgroup$
    – bob1
    Jun 25, 2021 at 10:10
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    $\begingroup$ Your description of inactivated vaccines is partially confused with a description of live attenuated vaccines. Both of the vaccine type descriptions are missing key elements such as how they generate an immune response, and advantages and disadvantages of each. $\endgroup$
    – Armand
    Jun 25, 2021 at 10:26

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