Why does the timeframe between vaccine doses differ between adults and children?

Blog post by Marica Micallef

Can the Health Authorities explain why the timeframes for children between the first and second dose are shorter than those of adults? Is it the case because children are being given a milder dosage?

[I cannot understand this. I took both the first and second dose of Astra{Zeneca} and I did not have any effect. Between both doses, there was a time span of two months. Now they have sent me the letter to vaccinate my five-year-old son {whom I am not going to vaccinate} with Pfizer and there are only 20 days between the two doses.]

Can the local health authorities provide a scientific explanation about this? I am sure that science has the answer.