Even opponents agree it works. The debate is over the cost of getting there.
538 Article Debunks it’s own title
Immune Response after re-exposure
Concepts of Biology – 1st Canadian Edition
23.2. Adaptive Immune Response
Outbreak Overshoot
The effect of public health measures on the 1918 influenza pandemic in U.S. cities
Hong Kong Flu Partial Immunity from Asian Flu
Increased deaths in non-coronavirus sufferers