Parents have threatened to sue a school and go after them for GBH if their children are given the COVID-19 vaccine without their consent.
In total, 17 parents of pupils in years seven, eight and nine at Tretherras School, in Newquay, Cornwall, have signed a "cease and desist" legal notice.
This autumn, all children aged 12 to 15 years are being offered the first dose of the Pfizer vaccine, and government guidance says parents are "asked for consent".
But if it is refused and the child is deemed "competent" then "the parent cannot overrule the decision" and the child can "legally give consent".
Parents at Tretherras School have sent a legal letter to the head, year leaders, safeguarding team and governors.
They want the school to confirm it won't vaccinate kids without parental consent and the date of any proposed jabs.
It threatens to sue if the school "fails to satisfy my concerns", in the letter dated 26 September.
But Tretherras School has denied it is planning to jab students without their parent's permission.
A spokesperson said: “No child will be immunised in school without parental consent.
"If there is a disagreement between parent and child, a meeting is called between the family and the school immunisation team to discuss further.”
The parents believe their kids should not be given the vaccine because clinical trials are ongoing and there is a "lack of long term data".
A parent who signed the letter, and has a 13-year-old boy at the school, said: “We decided as a group that our children don't need the jab.”
Watch: Coronavirus vaccine: UK nears five million second dose jabs
Schoolchildren aged between 12 and 15 will be vaccinated this autumn after parents are contacted to give consent - but in cases where the parents refuse, the children may be able to consent for themselves after being judged for 'Gillick competence'.
This would allow a child under the age of 16 to consent for themselves if they are deemed as having the capacity and maturity to understand what they are consenting to and are fully aware of what it involves.
The parents at Tretherras School want officials to promise not to use Gillick Competency.
The legal letter also said they will "bring a case of harassment and emotional harm" against the school should "further harassment by school staff of our children regarding the wearing of masks".
The legal notice was presented after the Joint Committee on Vaccination and Immunisation (JCVI) stating the benefits of vaccinating 12-15 year olds may not outweigh the potential harms.
The JVCI said: "The assessment by the Joint Committee on Vaccination and Immunisation (JCVI) is that the health benefits from vaccination are marginally greater than the potential known harms.
"However, the margin of benefit is considered too small to support universal vaccination of healthy 12 to 15 year olds at this time."
The UK’s four chief medical officers decided to approve the jab for the younger age group after concluding it was clinically justified due to the likelihood schools would be less disrupted as a result of the rollout.
The decision took into account the impact of the pandemic on children’s education as well as the risks to their mental health from missing school.
While children are less susceptible to severe COVID-19, they can spread the virus to others, including vulnerable populations that are more at risk of severe illness.
Watch: How the world could be better after COVID