Someone asked me if SARS-COV2 mRNA vaccine could create the wrong spike protein and have a negative effect on our immune system. Since I know too little about biology I couldn't answer that and started doing some deeper research than I did before on mRNA. But I can't seem to find anything to answer my question (it most probably is because I lack the knowledge in this field).

So here are the two main questions of this problem:

  • When created, can the mRNA vaccine have flaws and when injected generate a different spike protein than the SARS-COV2 one ?
  • If so can the spike protein be harmful to our system in any way ?

I am sorry for any term not correct in this context.


1 Answer 1


The mRNA won't be entirely perfect, but the imperfections will not matter.

The spike protein is big, encoded by thousands of base pairs in the virus. In the virus itself, it's not entirely homogeneous: there are always going to be small mutations that cause different variants to be produced, but nearly all of those are nearly identical.

The mRNA in a vaccine may also have some degree of copying errors introduced during amplification, which will produce some distribution of variants. Though the specifics are different, random copying errors in a synthetic process and random copying errors in natural viral replications will produce qualitatively similar types of distributions (more serious errors producing truncations and recombinations can occur in both as well, but similar arguments apply and they're even less likely to be functional).

Moreover, since only the spike protein is there, it can't actually produce a damaging infection, only teach your immune system what an infection looks like. Finally, since it's easy to validate a batch of mRNA via sequencing, ordinary quality control procedures should be fine to make sure what goes into the vial is what was planned (modulo the variances described above, when they are at a low enough frequency to fall below the threshold of discrimination).

In short: don't worry about the mRNA varying. If you're going to worry about something, worry about the virus varying enough that our nice, tightly controlled mRNA doesn't match it any more.

  • 1
    $\begingroup$ This answer providea no evidence in support of the statements made, so that although the poster may have accepted it, he has no basis on which to assess whether or not it is correct. Furthermore, by repeating the unusual term "flaws", without any explanation of what is meant or how you imagine they arise, your answer lacks conviction. $\endgroup$
    – David
    Commented Jan 22, 2021 at 18:20
  • 3
    $\begingroup$ @David What additional details are you looking for? I typically try to answer questions at a level appropriate to the apparent expertise of the asker, thus focusing on what I perceived to be the core of the question, rather than going into full details. $\endgroup$
    – jakebeal
    Commented Jan 22, 2021 at 19:01
  • $\begingroup$ @David you are right I have no basis to really know whether or not this is a good answer. But Jake you can also go into full details, I will read and research terms I don't know of yet. $\endgroup$ Commented Jan 23, 2021 at 22:15
  • $\begingroup$ I would prefer a detail answer even if I can't get everything than an incomplete one. $\endgroup$ Commented Jan 23, 2021 at 22:18
  • $\begingroup$ I've added additional detail to explain the reasoning more thoroughly and precisely. $\endgroup$
    – jakebeal
    Commented Jan 23, 2021 at 22:28

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .