Some key demographics [1]:

                             Haiti     USA
    Life expectancy (M)        62       75
    Life Expectancy (F)        67       80

Obesity rate [2] is 36.7% (USA) vs 22.7% (Haiti).

So the most vulnerable population (ie older people) are way less prevalent and obesity is significantly lower. I don't know if that fully explains things or not.

I really hate these stories though because they always bring out confirmation biased Antivax Andys.

[1]: https://www.worlddata.info/country-comparison.php?country1=H...

[2]: https://www.mylifeelsewhere.com/compare/united-states/haiti