Microchip and vaccine needles questions

I read somewhere on the internet about the possibility of introducing bacteria from the skin and fur under the skin when vaccinating. They say this is what causes the lump that sometimes forms. So isn't it even more possible when microchipping? I know the practice is very necessary but after I found out about why my MuShu gets lumps from vaccinations, I was just wondering about the microchips as well. One website said that if vets would use smaller needles during vaccinations, a lot of lumps would be avoided as well. But does that makes sense since bacteria are so small? I do recall the site stating that the smaller the needle, the less skin is punched into the area under the skin. Any thoughts on this topic?

I asked about disinfecting the site when I began holiday sitting a diabetic pug who needed daily insulin injections. Three separate vets told me that unless the site was really really dirty it just wasn't necessary. (I didn't believe the first two - I was soo stubborn. ) One even added that it would probably sting the skin as well (I was thinking of alcohol wipes.) Granted the chipping needle is much bigger, but I would think the same principle applies.

Sometimes we can be too careful, then we end up with a compromised immune system because it just hasn't had the normal amount of challenges.

I've never heard that claim before and I would question the source. The lump from vaccinations is usually a deposit of what is in the vaccine...that is why when they do a needle aspirate they will see the rabies virus (dead of course) or whatever. In my 15 years of rescue work I have seen more than 1000 pugs given microchips and there has never been an infection. In my mind, any miniscule risk of infection would FAR outweigh the benefits if having your animal identifiable if it became lost or was stolen.

My current foster is taking immuno-suppressive drugs and I asked about microchipping her and the specialist said that as long as the equipment is sterile (and it is) then there was no risk to her. So I can't imagine it would be a risk to a healthy dog. And the lump from vaccines is as Roxane said or on occasion, a vaccine reaction--either to the vaccine itself or the carrying fluid used.

Good to know the more medical and scientific explanation for vaccination lumps. Thank you! I never really took the needle thing as gospel but just made me think. That one site even sited what guage needle is better to use. But I can't seem to find the website it was in. If I ever find it again, I'll pass it on. I started on this journey when MuShu consistently got lumps from the shots and also she would develop scabs on the inside tips of her ears! The vet actually told me that "some dogs" have that reaction after vaccinations! Doesn't that tell them something?!!!
Anyway, I agree that the benefits of microchipping outweigh the risks. At least with the evidence thus far.