As with other vaccines, the administration of Engerix-B should be postponed in subjects suffering from acute severe febrile illness. The presence of a minor infection, however, is not a contraindication for immunisation.
Because of the long incubation period of hepatitis B it is possible for unrecognised infection to be present at the time of immunisation. The vaccine may not prevent hepatitis B infection in such cases.
The vaccine will not prevent infection caused by other pathogens known to infect the liver such as hepatitis A, hepatitis C and hepatitis E virus.
The immune response to hepatitis B vaccines is related to a number of factors, including older age, male gender, obesity, smoking habits and route of administration. In subjects who may respond less well to the administration of the hepatitis B vaccines (e.g. more than 40 years of age etc.), additional doses may be considered.
In patients with renal insufficiency including patients undergoing haemodialysis, HIV infected patients and persons with an impaired immune system, adequate anti-HBs antibody titres may not be obtained after the primary immunisation course and such patients may therefore require administration of additional doses of vaccine (see Dosage: Patients with renal insufficiency including patients undergoing haemodialysis under Dosage & Administration).
As with all injectable vaccines, appropriate medical treatment and supervision should always be readily available in case of rare anaphylactic reactions following the administration of the vaccine.
Syncope (fainting) can occur following, or even before, any vaccination as a psychogenic response to the needle injection. It is important that procedures are in place to avoid injury from faints.
Engerix-B should not be administered in the buttock or intradermally since this may result in a lower immune response.
Engerix-B should under no circumstances be administered intravascularly. As with any vaccine, a protective immune response may not be elicited in all vaccinees (see Pharmacology: Pharmacodynamics under Actions).
The potential risk of apnoea and the need for respiratory monitoring for 48-72h should be considered when administering the primary immunization series to very premature infants (born £ 28 weeks of gestation) and particularly for those with a previous history of respiratory immaturity. As the benefit of vaccination is high in this group of infants, vaccination should not be withheld or delayed.
Effects on Ability to Drive and Use Machines: The vaccine is unlikely to produce an effect on the ability to drive and use machines.