I'm sure when your child was immunocompromised they would have been in strict conditions whereby everyone in contact had to sterilise their hands before coming near or in contact.
But there are lots of immunosuppressed people walking around, post transplant for example, who can’t live their lives in a sterile bubble. Not handwashing puts them at risk, not just of prolonged illness, but also of death.
NHS website advice
Why is it so important to wash hands properly?
Washing your hands properly removes dirt, viruses and bacteria to stop them spreading to other people and objects, which can spread illnesses such as food poisoning, flu or diarrhoea.
"Hands are easily contaminated with faecal bacteria [poo] when going to the toilet and this can be easily spread on to other things you touch, including food," says Professor Jeremy Hawker, a consultant epidemiologist at Public Health England.
"Unfortunately, not all people consistently wash their hands after going to the toilet or before handling food.
"Washing your hands with soap and water is sufficient to remove dirt, viruses or bacteria and it can reduce the risk of diarrhoea by nearly 50%."