Why would we place the infirmary right next to the place that's most likely to be breached? The first floor under the entrance is obviously going to be a false first floor, with an emergency first aid backup infirmary, small basic kitchen and a tiny bedroom.
And from the second floor downwards, the bunker will obviously be built in a diagonal, parallel pattern in case someone might use a bunker buster. The floors will be modular in case of an earthquake and the walls will have external, retractable spikes and flamethrowers in case mutated wildlife tries to dig its way in through them.
Just some basic precautions really...