Is this a new thing? Flu shot related

[MCatLvrMom2A&X]

It is time again for the free flu shots done at dd's school this year the paper says:

Children 2 years up to 9 years of age getting a flu vaccine for the first time will need two doses of vaccine the first year they are vaccinated, with the first dose ideally being given In September or as soon as vaccine becomes available. The second dose should be
given 28 or more days after the first dose. The first dose "primes. the immune system; the second dose provides immune
protection. Children who only get one dose but who need two doses can have reduced or no protection from a single dose of flu vaccine.
Two doses are necessary to protect these children. If your t.hild needs the two doses, begin the process early, so that children are
protected before influenza starts circulating in your community. Be sure to follow up to get your child a second dose if they need one. It
usually takes about two weeks after the second dose for protection to begin.

Is the bolded part a new thing or is this standard?

[Fyrestorm]

I think they started that last year or the year before...something about not getting a strong enough immune response for one dose in in children the first time out.

[Gitti]

Twice the mercury to make sure removing mercury from most other vaccines does not improve the autism rate and make everyone suspicious.

[whosnext]

but why do they need two doses for the first time only? and why only up to age 9?

[Gitti]

Give them time, soon everyone will need two doses.

[spero]

It's not new. Two doses rec'd for kids is standard practice AFAIK, and has been for the last several years at least.