Covid 19 coronavirus: Does too much handwashing weaken my immune system?

New Zealand Covid-19 resurgence - A timeline of events. Video / NZ Herald

People have been obsessed with cleanliness during the Covid-19 pandemic.

Supermarkets were forced to put limitations on hand sanitiser sales and in some cases sold out completely, meanwhile, Trade Me even restricted pricing.

At the start of the year, officials told us washing our hands well and often was one of the best protections we had against it.

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But can we be too clean and is too much hand cleaning or sanitiser use bad for my immunity?

The hygiene hypothesis theory suggests a lack of exposure to microbes from environments too clean can lead to allergies and certain autoimmune disorders.

Experts in New Zealand say there is no evidence to suggest this is the case but also told the Herald a little bit of dirt wasn't a bad thing.

"There is no evidence whatsoever that regular hand washing will be of any harm," University of Otago epidemiologist Professor Michael Baker says.

"The bacteria that people have are very adaptive at being able to pass from person to person, so hand washing is key to interrupting that process."

Professor Michael Baker Department of Public Health, University of Otago. Photo / Supplied

University of Otago department of biochemistry Professor Kurt Krause and Massey University Professor David Hayman both agreed.

Krause recommended people use soap and water when they could, opting for hand sanitiser when the traditional method for hand cleaning wasn't available.

Constant hand sanitiser use can lead to chapped skin, with cracking more susceptible to bacteria so it's important to check your hands, he said.

"That's one reason why I prefer soap and water. Good ol' soap and water for 20 seconds will kill the virus and won't cause any harshness to your hands," Krause said.

However, there is a fine line between exposing people between good bacteria and bad bacteria which is hard to portray, Hayman says.

"It's one of those things, we want to limit us from getting some infections but on the other hand we want exposure to good bacteria," he said.

"It's like your probiotic yoghurt, you want to have a good natural gut flora because we're not sterile but you don't want campylobacter going through you so you're vomiting."

Krause says people shouldn't strive for no bacteria, but to strive for having clean surfaces and clean hands.

He thought getting dirty wasn't a bad thing, especially as a child, but people should make sure they clean up properly afterwards.

Both Krause and Hayman reiterated Baker's comments about a lack of evidence keeping clean weakens your immunity.

Hayman also had a strong message for Kiwis, to keep doing what they're doing when it comes to personal hygiene and handwashing.

It comes after all Covid-19 patients in the community have recovered, with Auckland to move to alert level 1 tonight. There are three new cases in managed isolation today.