I totally agree with the pp. You can stop any time.
The only reason for boosters is that ca 5% of children vaccinated show no antibodies to the virus that they were injected with. So, instead of checking every child's titres, they (CDC) decided to just vaccinate every child a second time.
For some viruses a few kids do not show antibodies even after two vaccines, so, again, instead of checking every child's blood, they vaccinate all kids a third time.
There are some people who will never show antibodies, no matter how often they are vaccinated, but the CDC had to stop somewhere.
So, in reality there is no such thing as 'needing' the boosters, nor does it do more for the child. But the pharma makes plenty of additional money from that idea...(but that's another thread...).
You do not have to finish any series, there is no such thing.
Vaccines are based on a theory and the dose is based on guess work.
The sooner you stop vaccinating the better for the child. And like the pp said, you can start any time again.
We stopped vaccinating our 15 mo old grandson when we did some research. At that time we did one more shot - they told us it was a 'preservative free measle component' of the MMR. Who knows what he really got because now we know there is no such thing as a preservative free vaccine.
We continued to research some more and never did another vaccine. He is 7 years old now and perfectly healthy. Our second grandson is now 15 mo, not vaccinated at all and never will be vaccinated. He is the healthiest kid in his play goup.
Good luck in your research.