COVID-19 vaccines have shown to be effective at preventing vaccines but the big win for public health is reduced effects if you get it anyway. If you don't have co-morbidities your relative risk is very low but if you do have them, every precaution is worth taking.

The vaccines come in many forms but two of note are the Janssen COVID-19 vaccine (Ad26.COV2.S) and Pfizer-BioNTech (BNT162b2), distinct because Janssen only requires one dose.  And the latter made "mRNA" part of the cultural lexicon. 

Which one led to fewer hospitalizations? They were both outstanding but there is a winner.

An analysis of people last year in France included 689,275 participants vaccinated with Ad26.COV2.S and 689,275 participants vaccinated with BNT162b2. The mean age was 66 and about half were women, both similar in terms of socioeconomics and health. In the one to three month period after, there were 129 COVID-19–related hospitalizations among those vaccinated with Ad26.COV2.S, and 23 among those vaccinated with BNT162b2. In absolute terms that is a big difference but realistically both worked quite well against the one thing no one wants; being in a hospital.

With numbers so small confounders matter. While the pool for each vaccine may be similar on a demographic population level, on an individual level one person in 6,000 being in one group or the other causes a large swing in statistics.

It's not a bad idea to get a second dose of even the single dose vaccine if you are at high risk. There's no need to engage in the kind of fear and doubt that San Francisco does and tell people to get four shots - because they were anti-vaccine until 2021 and still don't think scientists know what they are doing.

The good news is they both work. The important thing is to get them.