Full vaccination is at about 65%, boosters are at about 25%, lower than much of Europe.

                                  Percent of US Population
    
                                  At least  Fully  
                                  one dose  Vaxed  Boosted
    Total                         75.4%     63.3%  39.5%
    Population ≥ 5 Years of Age   80.1%     67.3%  
    Population ≥ 12 Years of Age  85.3%     72.1%  
    Population ≥ 18 Years of Age  87.3%     73.8%  42.6%  
    Population ≥ 65 Years of Age  95%       88.2%  62.7%

It's reasonable to be measuring against eligibility when evaluating progress in administering boosters, but not being eligible for a booster doesn't really make someone less susceptible to infection, so it isn't the right thing to compare across countries.