So the question is not how many people have been vaccinated now but how many people were vaccinated as of say 3-4 weeks ago. And very few were in the US. In Israel, which got off to a much faster start, you arguably (there are some confounders) are seeing an impact already.
p.s. Is the US data starting to show any impact from vaccines? I doubt that. Per Israeli data, vaccines take ~2+ weeks to become substantially effective and then there are the usual lags beyond that (e.g. between development of symptoms and test results showing up in the data).
New cases and hospitalizations are starting to fall pretty quickly in the US. Seems to be a lot of fatalism that new strains will cause a 4th (?) wave. Not necessarily true if we can vaccinate people fast enough and keep other sensible measures in place.https://covidtracking.com/data