I have no doubt that everybody admitted to hospital now for whatever reason will have their Covid status checked. If the test is positive, then they have got it, though it is not necessarily the cause of their illness. False positive tests are very uncommon. If the test is negative, they still might have it, as unfortunately false negatives are common, up to one third or so. If someone tests negative but there are other things that suggest Covid - loss of taste/smell, hypoxia, consolidation on their CXR/CT scan, then they would still be treated as if they have Covid, though a repeat Covid test or tests would be done.

Covid is a cause of pneumonia - that is the commonest way it causes severe illness and death.

Somebody with a tumour on their CXR could have Covid like consolidation as well.

Even somebody admitted to hospital with a broken leg would be regarded as having Covid until this had been excluded - and one test, as discussed above, does not exclude it.