Hep B is genetically engineered vaccine (not derived from biological, infected cells like other vaccines) so its impossible to get Hep B from the vaccine. However, it is a completely foreign substance being injected into the body. My biggest concern, personally, come from stories Ive read of people being crippled with arthritis or other major immune system diseases.
I am going to quote an article from http://www.909shot.com/ I personally consider this site to be somewhat alarmist so I recommend that you do NOT read the personal stories of children damaged if you want to approach this factually and not emotionally, because they are very upsetting. They do, however have some great articles and info on legislation, etc.
Regarding the Hep B Vaccine from -this- article:
Hep B Vaccine Licensed By FDA Without Adequate Proof of Long Term Safety - In 1986, the FDA gave Merck & Co. a license to market the first recombinant DNA hepatitis B vaccine, which replaced the old hepatitis B vaccines made from blood taken from human chronic hepatitis B virus carriers. In awarding Merck & Co. and, later, SmithKline Beecham Pharmaceuticals, licenses to market their genetically engineered hepatitis B vaccines in the U.S., the FDA allowed both drug companies to use "safety" studies which only included a few thousand children monitored for only four or five days after vaccination to check for reactions. As "proof" their hepatitis B vaccine is safe to be used in children, Merck & Co. stated in their 1993 product insert that "In a group of studies, 1636 doses of RECOMBIVAX HB were administered to 653 healthy infants and children (up to 10 years of age) who were monitored for 5 days after each dose."
Merck & Co. found that injection site and systemic complaints, such as fatigue and weakness, fever, headache and arthralgia (joint pain), were reported following up to 17 percent of all hepatitis B injections. Because the FDA did not require drug companies to provide scientific evidence that hepatitis B vaccine does not compromise the immune and neurological systems of children and adults over weeks, months or years post-vaccination, Merck & Co. warns in the 1996 product insert that "As with any vaccine, there is the possibility that broad use of the vaccine could reveal adverse reactions not observed in clinical trials" and SmithKline Beecham (1993) has a similar warning that "it is possible that expanded commercial use of the vaccine could reveal rare adverse reactions
Another warning in the Merck 1996 product insert is "it is also not known whether the vaccine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity" and "it is not known whether the vaccine is excreted in human milk. Because many drugs are secreted in human milk, caution should be exercised when the vaccine is administered to a nursing woman." And, although doctors routinely inject hepatitis B vaccine into children along with many other vaccines such as DPT, HIB, MMR and chicken pox vaccine, Merck & Co. state in the 1996 product insert: "Specific data are not yet available for the simultaneous administration of RECOMBIVAX HB with other vaccines."
Hep B Vaccine Efficacy Also Questioned - All vaccines stimulate only an artificial, temporary immunity, and the length of immunity conferred by the hepatitis B vaccine and the future need for more "booster" doses later in life is still not clear. Merck & Co state in their 1996 hepatitis B vaccine product insert that "the duration of the protective effect of RECOMBIVAX HB in healthy vaccinees is unknown at present and the need for booster doses is not yet defined."
In the CDC Prevention Guidelines: A Guide to Action (1997), the CDC states "The duration of protection [of hepatitis B vaccine] and need for booster doses are not yet fully defined. Between 30% and 50% of persons who develop adequate antibody after three doses of vaccine will lose detectable antibody within 7 years but protection against viremic infection and clinical disease appears to persist." If immunity only lasts 7 years, babies vaccinated with hepatitis B vaccine may be candidates for more shots at age seven.