A statistical quirk in a non peer reviewed paper that panders to the fears of the anti vaccination brigade.
The two groups are not comparable .... in general the group of people who get vaccinated will have a higher proportion of people with reasons to do so .... poor health, overweight, high risk group etc .... the same people who have a higher mortality rate. Also, vaccination is targeted by health professionals on higher risk groups.
There's so many papers published every day that it's possible to find one that reinforces a particular belief. Flat earth, check .... MMR causes autism, check, All Thai girls are hookers, check.