The most suitable stabiliser for a vaccine fridge is the following Sollatek product:
Model : Sollatek SVS04-22 4A 1KVA 230V EURO 6min E7/VR.
This SVS is designed specifically to protect vaccine fridges and complies with WHO specification E7/VR.
The unit is rated at 4amps on full load and full boost and has a start up delay of 6 minutes.