There is (at least in France) an ongoing discussion about the Astra-Zeneca vaccine which is perceived as "outdated" because of the prevalence of new variants (the vaccine was designed based on the initial virus)(*).

How difficult is it to create a new vaccine that targets a new variant of the virus? (specifically adenovirus vector vaccines like the AstraZeneca one, but any general information is welcome as well)

My understanding is that the clinical trials are not needed anymore (in the same way as a flu vaccine is recreated each year without clinical trials because the difference is in the virus variants only) so is there a strictly biological, incompressible delay? (ability to target the new variant)?

My main question, related to biology, is above, the following alternative questions are OT for the site, but I am asking them in case they would be relevant:

  • Or is there a financial aspect? (too expensive to create a new vaccine)
  • Or is this because Astra-Zeneca believes that the current vaccine is OK, despite the backslash?


Please note I am not saying this is the case - I am just curious how hard it is to create a new vaccine for a variant.

  • $\begingroup$ Can you share some info regarding the fact that AstraZeneca vaccine is "outdated"? $\endgroup$ Commented Feb 25, 2021 at 10:39
  • $\begingroup$ @FabioMarroni: there is an ongoing discussion in the French news about the AZ vaccine (vs the others). This is the default vaccine for <65 yo patients and there is a reluctance of the population to use it because of reports about the fact they are not effective for the new strains. It may or may not be true (and is another interesting question), this triggered my main question (and the extra ones in the exact context of AZ). $\endgroup$
    – WoJ
    Commented Feb 25, 2021 at 10:53
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    $\begingroup$ @FabioMarroni: I updated the question with the last part of my comment to indeed give some context (in French, unfortunately) $\endgroup$
    – WoJ
    Commented Feb 25, 2021 at 10:57
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    $\begingroup$ Are you asking about vaccines in general or specifically about adenovirus vector vaccines like the AstraZeneca vaccine? I can imagine that the steps to adapt to new mutations differ between different types of vaccines. $\endgroup$
    – Arsak
    Commented Feb 25, 2021 at 11:05
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    $\begingroup$ @David: France was for context. If you feel that my question about a "strictly biological, incompressible delay" is indeed off-topic please vote to close. I was not completely sure myself that this would be in-topic but I do not think there is a better place (and I tried to keep it limited to biology) $\endgroup$
    – WoJ
    Commented Feb 25, 2021 at 18:41


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