> there's this difference between old US-style washing machines that just stir and don't heat and EU washing machines that have a drum that turns and always heat the water
This is one reason this study seems rather dubious. In fact all the machines (they provide a table with model numbers, one of which is not correct, i.e., “00” should be “DD”) are European front loaders, but what is more concerning is that a far as I could see, there seems to be no mention of whether or how the clothes were dried.
The problem I could see with European style/model front loaders is that they usually and often proudly use little water, water which could rinse pathogens that were released from fabric by soaps, rather than allowing them to effectively reattach to fabric, but that is just my theory, yet a valid consideration altogether.
Then there is the fact that three of the washer models are masher/dryer combos, which are not only notoriously bad at both functions but their performance and designs may have an impact on results too.
Another huge hole in this research is that there is no clear mention of the brand of detergent used, only the type, biological vs non-biological (presumably only one of each). From other common testing, we very well know that different detergents perform very differently, especially across the types of stains, let alone between machines, not to mention types of machines. So we must conclude, assuming all other things being fine, this research would only even be relevant in the UK.
But then there’s also the matter of whether the detergent, the amount of detergent, and even the washing machines are representative of those used not only in the UK, but by hospital staff at all. Nothing indicates that there was some questioning, let alone observation of staff on their usage, equipment, or practices.
Frankly, this research, even if it were only relevant to the UK is still full of huge holes, even some not mentioned that I won’t bother going into detail about.
It is the kind of research that grates me because it is such sophistry, has the appearance of science and the confidence in its conclusions, but in the details it just kind of falls apart as rather purely executed, assuming the best.
I wouldn’t even be surprised if someone did some digging and found conflicts of interest, even just indirect ones that the researchers are not even aware of. Backroom research, research for the purpose of driving a commercial agenda is far more common than people think. I know this for a fact because I’ve witnessed it in person many times, from the smallest levels mostly for personal “publishing” interests, to the highest multi-billion dollar expenditures that are basically little more than very elaborate, very orchestrated, very high level get rich con jobs.