Snooki's pretty well-known in the US, but Jonas Salk's got staying power. Salk was a big American celebrity in his own right and is probably better known than Snooki among the middle-aged and certainly the old in the US & UK. As most people in the US & UK are at least 35-40 that might be enough to make Salk better known overall in those two countries.

Snooki does gets more hits & searches on Google but Salk's been a name for far longer and even holds his own against some rock stars in mentions in books.

Salk & Snooki are presumably less famous in non-Anglophone countries, and Salk must be worse off in that respect (reality TV antics better overcome language barriers), but he still has his half-century headstart, and the global effort to beat polio must've raised Salk's profile in quite a few countries.