You should be able to see that Covid-19 is in fact a disease listed in the table on the wikipedia page you reference. You should also be able to see that the percentage required for herd immunity effect to begin (the 'herd immunity threshold') is a function of the R0 level for each disease.

In addition, to question of "can anyone really say for covid-19", I suppose the answer is 'No, but I would trust that the consensus of the scientific community of infectious disease experts is the best estimation we can get.'