Hepatitis B vaccine is absolutely contraindicated in patients who:

A. Were born at less than 32 weeks gestation: Prematurity is not an absolute contraindication to the hepatitis B vaccine. Preterm infants are actually recommended to receive the vaccine because they remain vulnerable to hepatitis B virus infection. Although infants with very low birth weight may have a reduced immune response initially, vaccination is still administered with possible adjustments to the schedule based on birth weight and maternal hepatitis B status. B. Are pregnant: Pregnancy is not a contraindication to hepatitis B vaccination. The vaccine contains recombinant hepatitis B surface antigen produced through genetic engineering rather than live virus, making it safe in pregnancy. Vaccination during pregnancy may be indicated if the mother is at risk of exposure, helping prevent maternal infection and vertical transmission. C. Are on hemodialysis: Individuals undergoing hemodialysis are actually considered a high-risk group for hepatitis B infection due to repeated vascular access and potential exposure to blood products in dialysis settings. For this reason, hepatitis B vaccination is strongly recommended in these patients, often using higher vaccine doses or additional doses. D. Are allergic to yeast: The hepatitis B vaccine is produced using recombinant DNA technology in yeast cells, specifically Saccharomyces cerevisiae. Individuals with a documented severe hypersensitivity reaction to yeast may develop allergic reactions if vaccinated. A known severe yeast allergy represents a true contraindication to receiving the hepatitis B vaccine.