If natural herd immunity doesn’t work then how do you explain the resolution of the 1918 influenza pandemic without a vaccine? I understand that viruses mutate all the time but once you have had the virus there is often protection to some future variants. All of this is likely moot however as it appears that this current virus will become endemic and we will need yearly vaccines like for flu. Yearly vaccines are like playing catch-up. Current flu vaccines are in general no more than 30 to 70 percent effective in preventing disease. Why is the CDC and the US the only nation that does not recognize natural immunity as protective against future infections? Is it imperfect? Yes. But as we are now learning so are vaccines. People with triple vaccines are still getting the virus.