I checked, and your friend can get an exemption based on religious or medical, but not philosophical, reasons. Here's a link to send her that explains the religious exemption. She does NOT have to belong to a church that is against vaccines.
http://www.gval.com/exempt.htm
I do believe there is a link between autism and ALL vaccines, not just those containing mercury. Send her this link, too, it shows the ingredients in the vaccines.
http://www.informedchoice.info/cocktail.html
I do not believe it is the SOLE source of autism, though, or my child would not be autistic, because he's never received a single shot. I believe that these kids are born with autism in them, but it takes environmental factors to trigger it. Their immune systems typically are under-developed, making them more susceptible to poisoning from things like chemicals in foods and cleaning products we use, and more 'allergic' to toxins and ingredients that are in the vaccines and every day household items. For my son, signs were there from birth, and I believe that it's whatever I was exposed to when I was pregnant with him. But who really knows. The important thing is, we as parents need to do whatever we can to safeguard our children, and in your friend's case, it doesn't matter why her child is autistic. All she can do know is try her best to keep it from getting worse or regressing. I believe she's totally right that receiving ANY other vaccines could cause a regression, but nobody can say for sure. In the end, she has to do what she feels is right.
A couple of things were brought up that she's going to hear a lot, that I want to address. First, is the old 'remember how bad the diseases are that we vaccinate for'. Nobody on the anti-vaccine side is saying these things are not bad. But there is no sound proof that vaccinating caused these diseases to diminish; these diseases were already on the decline when vaccines were first introduced, so you can't say that the vaccines made them vanish. And, some of the diseases we vaccinate for are only contracted by the person who has received the vaccine in the first place. So, yes, she could vaccinate against them, but there's no 100% guarantee that her child will not get that disease, and it could very well cause the child to get the disease she was hoping he wouldn't get! Also, when you look at epidemics in the US, they are always in communities that typically vaccinate, not communities that as a whole don't vaccinate, like Amish communities. What does that say about vaccine effectiveness?
The second argument is 'there's no proof that vaccines cause autism'. That is half right. There is no proof that vaccines CAUSE autism, but there are no studies done to see if they can CONTRIBUTE to autism. At least not done by the medical community, because that would cause a lot of payouts due to lawsuits if people found out the truth. But there are many smaller studies out there (you have to look for them) that support that they can contribute to autism. However, here's my issue. Science and the medical community is ALWAYS changing their mind on 'scientific evidence', so I don't rely on it. We all can think of different scenarios where we're told 'this works' or 'this causes this', only to have them change their mind 10 years later. When it comes to kids, that's not reliable enough. I will not wait for someone to tell me that I was right all along, instead I will use my own common sense about what I'm allowing to be put into my kids bodies. Please pass all of this onto her, because unfortunately we live in a society that doesn't respect parents rights to make choices for their kids, and she's going to need to understand why those of us against vaccines, are against them. Kudos to you for doing some research for her, that is a true friend, whether you agree with her or not.