Auckland Regional Public Health Service (ARPHS) is investigating a tenfold increase in norovirus outbreaks in the region's early learning services in the last month.
During November, ARPHS responded to 29 norovirus outbreaks, with 21 of these being in early learning service (ELS) facilities. About 64 staff and 280 attendees at these services became unwell.
In the same period last year, ARPHS responded to nine outbreaks, with just two being at ELS facilities.
Medical Officer of Health Dr Jay Harrower said ARPHS has identified that some centres with outbreaks have been cleaning with ammonia-based products because these were marketed as inactivating the novel coronavirus.
"There is a common factor in the sharp rise in norovirus outbreaks in Auckland early learning centres over the last two months. Most of the centres with norovirus have moved away from chlorine bleach for cleaning."
Dr Harrower urged centres to use hypochlorite (chlorine bleach) products for all cleaning, and to use them regularly and thoroughly.
"It is hypochlorite or bleach that will kill norovirus on surfaces, and can also prevent the spread of coronavirus as well. Ammonia and alcohol based solutions do not completely inactivate norovirus."
Norovirus symptoms can include feeling or being sick, diarrhoea, stomach cramps, headache, low-grade fever, chills and muscle aches. Symptoms usually last for two days.
Norovirus can survive outside the body, so hard surfaces, toys, plates, cutlery and other objects can become contaminated and lead to others becoming ill.
Good hand hygiene - washing and drying hands thoroughly and often - is the most important action in preventing spread of the virus.
ARPHS has written to managers of all early learning services about the recent spike in outbreaks, asking them to send children home if they have diarrhoea or vomiting. They should not return until symptoms have stopped for at least 48 hours.
Very young children should be supervised while washing their hands before and after eating and going to the toilet if necessary. Staff should also wash hands well after changing nappies or handling soiled clothing.
Norovirus is highly contagious, and just one child with the illness can spread it to many other children, staff and their families at home, Dr Harrower said.
"While most people make a quick and full recovery, very young children can become unwell enough to need hospital care.
"It can be difficult for whānau to take time off work when they have sick children, but it is important to remind parents and caregivers that tummy bugs are very contagious. It is highly likely your child will infect others, and outbreaks can lead to centre closures."
Meanwhile, the number of norovirus outbreaks in aged residential care is dropping and is below the same time last year.