[Sephiroth]

Originally Posted by jonbxx

Difficult question! Some parts of the spike will give a better immune response than others. But, some parts of the spike differ by more than other parts. As an example, this paper - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7166309/ compares the spike of SARS-COV-2 (COVID) and SARS-COV (SARS) Super techie paper but check out figure 1(a) which shows different parts of the spike and how similar they are to each other. It varies between being 100% identical and 51%.

We really want to raise antibodies against the receptor binding domain (RBD) as this will not only get the immune system to recognise and destroy the virus but also, as a bonus, stop the virus from binding and entering cells. The RBD is only 74% similar so there’s a chance the COVID vaccine might not protect against SARS.

One huge advantage of the new vaccine types such as the mRNA vaccines and the Oxford/AZ vaccine is that they are ‘platform’ vaccines where you can very easily drop in a new RNA or DNA sequence to create a new vaccine. We are talking a couple of days here plus efficacy testing.

Excellent document. I found, as a layman, the following texts to be informative from my particular aspect:

The overall percent protein sequence identity found by the alignment was 76% (Figure 1(a)). A breakdown of the functional domains of the S protein, based on the SARS-CoV S sequence, reveals that the S1
receptor-binding domain was less conserved (64% identity) than the S2 fusion domain (90% identity).

(page 3311 = 4/18)

At present, SARS-CoV-2 is behaving in a distinct manner compared to SARS-CoV. We believe our findings are of special importance considering that the available data indicates ACE2 as a suitable cellular receptor for SARS-CoV-2 entry

(Page 3321 = 14/18)

Maybe an oversimplification - but this tells me that genuinely it is not known the degree to which the vaccines can deal with other coronaviruses and imo, it tends to the negative depending on the precise binding opportunities for any specific virus and the cells to which they prefer to bind.