Any parent can be forgiven for feeling perplexed, if not alarmed, by the rapid reversal of the Government's position on Covid vaccination in the under-18s.
Less than three weeks ago, the Joint Committee on Vaccination and Immunisation (JCVI) ruled out the 'routine use of universal vaccination of children' as data suggested the benefits did not outweigh the risks for youngsters.
Yesterday we learned the jab is to be offered to 16 and 17-year-olds after all.
So what is going on and how worried should parents and their teenagers be about the claims and counter-claims on safety?
Tens of millions of Britons are now double-jabbed – part of a coronavirus shield that protects us individually as well as those around us.
Less than three weeks ago, the JCVI ruled out the 'use of universal vaccination of children'. But yesterday we learned the jab is to be offered to 16 and 17-year-olds (stock image)
But vaccine availability has largely been limited to adults. That has set us apart from many other countries, including the US, Canada and France, which are routinely vaccinating all over-12s.
That does not mean that we are lagging behind. On the contrary, assessing the benefits of vaccinating youngsters against any possible risks is an on-going process.
And now JCVI scientists have analysed further data on vaccine safety and also taken into consideration the impact of the pandemic on school closures.
They are confident that the jab is safe for teenagers and so issued new recommendations.
This is good news. New infections are still flourishing – and largely in younger age groups – fuelled by the emergence of the more transmissible Delta variant.
Some people think this doesn't matter, given that many youngsters appear to be largely asymptomatic and very few suffer long-term effects.
But it matters a great deal because they can still infect others – especially vulnerable individuals, including those who cannot have the vaccine.
It will also matter a great deal come autumn when schools return. A surge in cases could have serious consequences for the education of our youngsters and wider society.
I understand this decision has been greeted with caution by some parents who worry about potential longer-term consequences. And there is, I know, particular concern about fertility in the wake of reports of menstrual irregularities linked to the vaccine.
Parents – and teenagers – are right to ask questions and they deserve honest answers.
But too much of this debate is being played out in the lawless world of social media – often in a post from an anonymous 'doctor' or 'my friend who is a nurse' or someone from the 'anti-vax' movement.
Such accounts have assiduously and shamelessly fed lies and misinformation to the public from the start of the pandemic.
This sort of content, steeped as it is in conspiracy and paranoid thinking, can prove more exciting than the dry pronouncements of boring old experts – and it is being lapped up by the young.
Well, I do hope young people and their parents will listen to this boring old scientist when I tell them that all the evidence shows that Covid vaccines are every bit as safe for the young as they have proved in the elderly who were first in the queue many months ago.
And as for fertility concerns, anecdotes and hearsay are no match for clear and rigorous evidence – and our evidence is that the vaccine has no effect whatsoever on the male and female reproductive systems.
What we do know is that the Covid virus can spread to the reproductive organs – it has been found in testicles and ovaries.
In other words, any young person who is concerned about their future fertility should, in my view, have the vaccine.
Getting jabbed is the right thing to do to protect yourself and others.
Dr McKay is a senior vaccine research scientist at Imperial College London.