First, in an article on new vaccine boosters in USA today there is this revealing statement:

Any revised Moderna vaccine would include a lower dose than the original, Moore said. The company went with a high dose in its initial vaccine to guarantee effectiveness, but she said the company is confident the dose can come down, reducing side effects without compromising protection.

Arrgh! Why wait for a new vaccine??? Fractional dosing now!

A microneedle patch for vaccines.

The same article also notes:

One of Moderna's co-founders, MIT professor Robert Langer, is known for his research on microneedles, tiny Band-Aid-like patches that can deliver medications without the pain of a shot. Moderna has said nothing about delivery plans, but it's conceivable the company might try to combine the two technologies to provide a booster that doesn't require an injection.

The skin is highly immunologically active so you can give lower doses with a microneedle patch. The microneedles are sometimes made from sugar and don't hurt. Microneedle delivery, however, can cause scars but I say apply the patch where the sun don't shine and let's go!

Second, Canada's NACI has now endorsed mix and match for the AZ and Pfizer and Moderna vaccines. First Doses First has put Canada in very good shape (now ahead of the US in percent of the population with at least one dose) and this was always part of the FDF plan--delay second doses to get out more first doses and then, when supplies increase, give second doses, possibly with a better vaccine.