Yes, there is no credible evidence of your claim. The big disease waves stuck most natives before they ever saw a European, after contacted peoples caught disea

Yes, there is no credible evidence of your claim. The big disease waves stuck most natives before they ever saw a European, after contacted peoples caught disease in the normal fashion. The very few later documented attempts we have are almost completely ineffective, and often from people in a very desperate situation (e.g., besieged and dying of smallpox) - just a last ditch gambit that never accomplished its goal.