Negative vaccine efficacy – a collation of evidences.

https://www.thedesertreview.com/opinion/columnists/negative-vaccine-efficacy---dr-paul-alexander-sounds-the-alarm/article_2226ec36-aeb6-11ec-8772-03a7ae44197e.html

Negative Efficacy is doctor-speak for a disease-promoting effect in a drug. In the case of a vaccine, Negative Efficacy means the vaccinated person is more likely to get infected than the unvaccinated.

In the real world, whenever we see the phrase Negative Efficacy associated with an experimental drug, it usually means the chance of death, infection, or serious disease is higher with the drug than without, and the term Negative Efficacy is used.