An early subunit vaccine, for hepatitis B, was made by isolating the virus from the plasma (the fluid component of blood) of people who were infected and then purifying the desired proteins.

• 先前一种针对B型肝炎的次单位疫苗，是利用受感染者血浆（血液的液体部份）中分离出来的病毒，再经纯化得出合适的蛋白质。