How fast could mRNA COVID manufacturers switch from the Wuhan strain to e.g. B.1.1.7 and why?

Question

I understand that the time it took Modena to go from the SARS-CoV-2 sequence to shipping doses for clinical trial was 44 days:

https://www.modernatx.com/modernas-work-potential-vaccine-against-covid-19

I don't know exactly what happened in that 44 days, but I am guessing it was things like synthesizing a DNA template, making sure that the protein would fold, maybe figuring out how to purify it, printing the shipping labels, etc.

If Modena (or Pfizer) wanted to switch their vaccine from the Wuhan strain to the B.1.1.7 strain, how fast could they get a B.1.1.7 variant dose into someone's arm? I presume it would be less than 44 days, but what's a guess as to the fastest it could happen (assuming they didn't have to go through trials again)? Is it just like two days to synthesize the template DNA? If not, what are the other steps they would need to go through?

Answer 1

I found a different upper bound. From https://marginalrevolution.com/marginalrevolution/2021/01/the-new-strain-and-the-need-for-speed.html (emphasis mine):

One of the big virtues of mRNA vaccines is that much like switching a bottling plant from Sprite to 7-Up we could tweak the formula and produce a new vaccine using exactly the same manufacturing plants. Moreover, Marks and Hahn at the FDA have said that the FDA would not require new clinical trials for safety and efficacy just smaller, shorter trials for immune response (similarly we don’t do new large-scale clinical trials for every iteration of the flu vaccine.) Thus, if we needed it, we could modify mRNA vaccines (not other types) for a new variant in say 8-12 weeks. As Zeynep notes, however, the vaccines are very likely to work well for the new variant. It’s nice to know, however, that we do have some flexibility.

And this reference says that the BioNTech CEO said it would be 2-6 weeks plus testing.