The first subunit vaccines were separated from purified virus by detergent then centrifugation. This is extremely expensive but is the basis a of a recent vaccine against equine influenza where the haemmagglutinin is bound to phoshotidylcholine using Quill A detergent (from the soap oak) to make immune-stimulatory complexes (Iscoms). Iscoms are the size of a small virus.

More modern subunit vaccines are made by genetic engineering when the viral gene is inserted into E.coli. or baculovirus and expressed as protein which is then adjuvanted eg Feline Leukaemia Virus spike protein from E.coli with added QuillA and alhydrogel.