Define "herd immunity" in terms of R0.

To put more meat on the bone, vaccines are merely an intervention. But there are many interventions. The vaccine is not even the most effective intervention for COVID. For instance, countries that intervened with extreme lockdowns will likely outperform those with the vaccine. I would put money that the per capita infection and death rates of NZ will be lower than Israel a year from now.

Further, "herd" is meaningless since there are many herds. For instance, my "herd" has achieved "immunity" from AIDS without a vaccine. The intervention to achieve this is the avoidance of gay sex and IV drug use. There may be other "herds" that have not achieved immunity but mine has.

My "herd" has also achieved "immunity" from rabies without a vaccine. The intervention used to achieve this is the avoidance of rabid animals. There are other "herds" that may not have achieved "herd immunity" but mine has.

The list of diseases that fits this description is actually quite long.

I think the question that you actually want to ask is "how many pandemics have been stopped without a vaccine?" I think the answer to that question would be "most." For instance every flu pandemic, bubonic plague, cholera, etc. has ended without a vaccine intervention.

Question for you: Can you name a vaccine against a mutating respiratory virus in which the effectiveness has not degraded significantly over time?