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All posts for the month December, 2020

So, I have been reading up on many earnest reports describing the difficulty in transporting ultracold vials of mRNA vaccines (Pfizer especially).

People routinely lyophilize (freeze dry) RNA for shipment to sequencing facilities, and for shipment from oligo suppliers. Lyophilized nucleic acids are stable even at room temperature, at least for some time. Even RNA.

Why didn’t anyone at Pfizer consider lyophilizing their concentrated vaccines (or lyophilizing the RNAs and then shipping the diluent separately, if this would be necessary) so they can be shipped just at refrigeration temperatures? All a person would have to do on the receiving end is add diluent to the RNAs, dilute with water if needed to make the final doses of vaccine, and at each step simply make sure that RNAs are fully dissolved (usually one just waits about 5-10 minutes), mixed (you can do this by inverting the tube a few times, or gently vortexed) and treated with care to prevent addition of RNAses. Or in the case of diluting a lyophilized vaccine, you simply add the diluent and wait for dissolution, and mix gently. Why is this considered too difficult for a lab technician in a hospital or clinic? The Pfizer vaccine already has to be diluted, so presumably someone is entrusted with the ability to dilute and mix and administer.

It might be the case that the liposomes the RNAs are in won’t survive lyophilization, but they might. And if they do not, how hard would it be to mix up a liposome mix from reconstituted RNA, lipids, and buffer? Extrusion machines are probably cheaper than -80C freezers.