Passata is a sieved tomato sauce that's generally too thin and bland to be used as a pizza sauce without first reducing it a little. If you have nothing else and no time to reduce it then passata could be used but it would be a good idea to add some herbs and seasoning to give it more flavour.
In an ideal world your pizza sauce will consist of crushed San Marzano tomatoes, olive oil, oregano, basil and some salt and pepper but if you've run out of sauce in the middle of making your pizzas then what can you do...
As mentioned, in general passata sauce is too thin, so you'll either need to use a lot to get the flavour but then the dough will be too soggy or use a thin coating to stop it being too wet and sacrifice that intense tomato flavour that a good sauce adds.
Passata is also too bland to be a good pizza sauce, it's simply sieved tomatoes so there's no herbs or seasoning in there.
If you have no other options then I'd recommend getting the passata into a saucepan over a low heat and simmering it for a few minutes to reduce down and intensify the flavour. You could also add some tomato paste as well to help.
If there's no time for this then another option is to simply add lots of tomato paste to the passata to thicken it and improve the flavour. Add it a little at a time and stir it through until you get to the desired consistency.
You should also add some oregano and basil if you have any as well as some olive oil and don't forget to season with salt and pepper. Once all this is done you should have a much better sauce to work with, if you've reduced it then make sure to let it cool before adding to the pizzas and you should be good to go.
If you want to make sure you're covered in the event of running out of sauce half way through a pizza party or just having some spare available in an emergency then here's a couple of tips.
I like to keep a few individual pizza portions of my home made sauce in the freezer, I use these little freezer pots from Amazon as they're a good size for one portion and seal nicely meaning no leaks. This way you can save leftover sauce for another day and you can quickly defrost such a small portion in an emergency.
I like to keep a few tins of Mutti pizza sauce in the cupboard for emergency use, it's a good clean sauce without too much processing and has a nice texture. You can find it on Amazon here or the local supermarkets in the UK. I don't think it's available in the US or Canada but find one that's available in your area that you're happy with and be sure to keep a few at all times.
