Like being a virgin population in which the new pathogens could spread like wildfire, being totally unknown to their immune systems? We have just seen the same

Like being a virgin population in which the new pathogens could spread like wildfire, being totally unknown to their immune systems? We have just seen the same with covid, where the entire humanity was a virgin population. And covid mortality was basically nothing compared to smallpox and a host of other Old World diseases. Notably, the only disease to spread the other way round, syphilis, was very severe too. It took several generations for syphilis to mutate to a more chronic form. And, notably, even though famine and violence weren't exactly rare during the later colonial conquest of Africa, it usually wasn't the natives who died of diseases, but the whites, who just couldn't tolerate local diseases such as malaria, to which the indigenous population was somewhat resistant. There is a reason why the only significant white population in Africa is located in territories with more European-like climate, where the disease situation wasn't as dire as, say, in Congo.