A search for rapid review in PubMed has shown 1421 results:
As you can see the majority have been since 2020 (819 or 57%). Of these roughly half are related to Covid-19 (433 of the 819). But, in the same era there were around 82,000 systematic reviews (all topics) of which around 5,000 related to Covid-19.
So, if we say there were 83,421 evidence syntheses (1,421+82,000) then 1.7% were rapid reviews. In relation to Covid-19 it’s 8%. For historical context, between 2014-19 there were approximately 120,000 SRs published in PubMed and 460 RRs – so 0.4%.
So, RRs are increasing and Covid-19 has accelerated this; the need for rapid summaries is increasingly evident. It does make me wonder, prior to Covid-19, when RRs were often (heavily) criticised might – actually – RRs have been sufficient? It would have saved money, decisions could have been made quicker etc.