Flu shot makes COVID-19 worse, confirmed by Cleveland Clinic

Mechanistic evidence (prediction)

Proteins that contaminate influenza vaccines have high homology to SARS-CoV-2 proteins thus increasing risk of severe COVID-19 disease and mortality

Epidemiological evidence (confirmation)

Flu shot increases risk of COVID-19 Hospitalization 240%, ICU admission 204%, Hospital mortality 232%.

Safety of Influenza Vaccine during COVID-19

Among individuals with a positive SARS-CoV-2 test, patients previously vaccinated for influenza in 2019 were more likely to be hospitalized. Once hospitalized, they were more likely to be admitted to the ICU and die during hospitalization.

From Table 1: