Delta was particularly infectious due to some mutations, but are those mutations antithetical in some way to antibody production? Why can’t b-cells just update their response and block that pathway with a new vaccine?
My understanding is this was always expected to be whack a mole with the virus anyway. All other endemic coronavirus reinfect people.
The problem Delta presents to antibody-based protection is that there is a several day lag in the body's response to detecting the virus until it produces mass antibodies.
If the (small) number of circulating antibodies are overcome by a large viral load, and if the virus becomes transmissible in a shorter time period, it can "get inside the curve" of antibody response and result in a transmissible infection before the host mounts a full response. Delta is apparently a couple of days 'faster' than the previous Alpha strain in getting to the transmissible stage.
That makes covid a long run big problem. We’ll have to be repeatedly challenged with the antigen to keep antibody levels high. Kind of a minor inconvenience for some, but a large % of the population will not comply.
Edit:
It would seem that it is basically speculation at this point. Memory b-cell response effectiveness will depend on the binding affinity of its antibodies. A high binding affinity antibody producing memory cell will much more rapidly mount an effective response than one that must undergo further affinity maturation.
That's not to say that it's impossible. Chicken pox has a similar R0, but universal vaccination has greatly decreased the spread of the disease. At this point, it mainly occurs in small pockets of non-vaccination, and cannot spread significantly into the wider population. But that requires education and popular support, and is where we'll need to focus our efforts next.
[0] https://www.cnn.com/2021/07/29/politics/cdc-masks-covid-19-i...
Also, some people are not antivax, they are afraid of new mRNA technology. When the technology has had more time to bake, they will feel more comfortable.
Finally, Novavax will be coming online soon. That should help with some of the mRNA skeptics.
then they can get the Janssen (aka Johnson & Johnson) vaccine which is not based on mRNA but an Adenovirus vector.
Viral vector has only been used before for Ebola. All US vaccines execute custom RNA code that was spliced from the real virus. Viral vector just gets that code in the cell by a different method.