Thanks for the reply, but I think you misunderstood the particular point I was making about the difficulty of achieving herd immunity with existing (leaky) Covid vaccines.

One paper shows that leaky vaccines are good for the individual, but not necessarily good for herd immunity. The other shows that the current generation of covid vaccines are leaky.

Here is a 2022 published paper with more details

For clarity, most vaccines that are administered are not leaky and herd immunity can be achieved. This is particularly important for viruses like measles, smallpox and polio.