Most parents go out of their way to prevent their children from contracting chickenpox.

But a group in Boulder, Colorado, is doing the exact opposite - arranging 'chickenpox parties' to deliberately infect their children.

It is a technique that was used by families decades ago, before the varicella zoster vaccine was released in 1995, in an attempt to 'naturally' build up their kids' immunity to viruses.

The vaccine offered a far less arduous and less risky alternative: a dead or weakened form of the virus is injected into a child, stimulating antibodies to recognize the virus without making them sick.

However, as the state's thriving anti-vaccination movement gains steam, more and more are shunning the shot - and the trend of pox parties is making a resurgence, according to a report by 9News.com.

What's more, the group claim to be following advice from 'a friend that works at the CDC' and 'the UK's NHS', despite the fact that both the CDC and the NHS advise against this approach.

The group in Boulder, part of a growing anti-vaxxer movement, believe infecting their kids is safer than getting a varicella zoster vaccine, and they wrongly claim it's advice from the NHS and CDC

'I have been swamped with requests to have my daughter share chicken pox, and I can accommodate as many requests as possible,' a mother wrote in the private Facebook group, seen by 9News.com.

'We seem to have a pretty contagious wild virus here that started when my husband came down with the shingles around the middle of September,' she added.

'It seems to be a [week] or so before you notice results.'

She then offers specific times and days of the week when she can host visitors.

One of the messages posted in a private Facebook group seen by 9News.com

There are options for strategies. Either the child can simply spend time with infected people, or they can be 'tented' - putting them in a very small space filled with exhaled air for 30 minutes.

On top of that, the mother adds: 'Bonus for sharing snacks out of the same bowl. Also, bring the host mom something by way of thx. A casserole or tp or something!'

In essence, a bout of chickenpox and a vaccine do the same thing.

Both stimulate the body's defense mechanism to recognize the virus and fight against it in the future, making secondary cases of chickenpox unlikely, and potentially lowering the risk of related viruses, like shingles.

The risk with chickenpox, though, is that the virus can develop into further complications, including pneumonia, encephalitis, and group A strep, all of which can prove fatal in young, vulnerable, developing children.

Vaccines, meanwhile, are tested to ensure the lowest risk of complications.

As Dr Robert M Jacobson, a pediatrician and medical director for the Population Health Science Program at Mayo Clinic, has told DailyMail.com: vaccines are more rigorously checked for side effects than any other type of medication.

'Vaccines are the most tested thing that we as physicians prescribe, because they are being administered to millions of people so there is no room for error,' Dr Jacobson explains.

'Vaccines are tested in tens of thousands of people, compared to, say antibiotics to prevent infection from a tattoo, which are tested in hundreds.'

Nonetheless, over time, the rate of people foregoing vaccines is climbing, and these messages show parents believe turning back the clock 30 years would be better for their children's health.