Anti-Viral Vaccines

Rabies

Vaccines in General Use

• Hepatitis B
• Two vaccines are in current use: a serum derived vaccine and a recombinant vaccine. Both contain purified preparations of the hepatitis B surface protein.
• The serum derived vaccine is prepared from hepatitis B surface protein, purified from the serum of hepatitis B carriers. This protein is synthesised in vast excess by infected hepatocytes and secreted into the blood of infected individuals. A vaccine trial performed on homosexual men in the USA has shown that, following three intra-muscular doses at 0, 1 and 6 months, the vaccine is at least 95% protective.
• A second vaccine, produced by recombinant DNA technology, has since become available. Previously, vaccine administration was restricted to individuals who were at high risk of exposure to hepatitis B, namely: infants of hepatitis B carrier mothers, health care workers, homosexual men and intravenous drug abusers. However, hepatitis B has been targetted for eradication , and since 1995 the vaccine has been included in the universal childhood immunization schedule. Three doses are given; at 6, 10, and 14 weeks of age. As with any killed viral vaccines, a booster will be required at some interval (not yet determined, but about 5 years) to provide protection in later life from hepatitis B infection as a venereal disease.
• HEPATITIS B — Hepatitis B virus gene, aluminium hydroxide, mercury, formaldehyde. For the genetically engineered vaccine: aluminium hydrochloride, sodium chloride and mercury.
• Hepatitis A
• A vaccine for hepatitis A has been developed from formalin-inactivated , cell culture-derived virus. Two doses, administered one month apart, appear to induce high levels of neutralising antibodies. The vaccine is recommended for travellers to third world countries, and indeed all adults who are not immune to hepatitis A.

Vaccines in General Use

• Influenza
• Repeated infections with influenza virus are common due to rapid antigenic variation of the viral envelope glycoproteins. Antibodies to the viral neuraminidase and haemagglutinin proteins protect the host from infection. However, because of the rapid antigenic variation, new vaccines, containing antigens derived from influenza strains currently circulating in the community, are produced every year. Surveillance of influenza strains now allows the inclusion of appropriate antigens for each season.The vaccines consist of partially purified envelope proteins of inactivated current influenza A and B strains.
• Individuals who are at risk of developing severe, life threatening disease if infected with influenza should receive vaccine. People at risk include the elderly, immunocompromised individuals, and patients with cardiac disease. In these patients, protection from disease is only partial, but the severity of infection is reduced.
• Varicella-Zoster virus
• A live attenuated strain of varicella zoster virus has been developed. It is not licensed in South Africa for general use, but is used in some oncology units to protect immuno-compromised children who have not been exposed to wild-type varicella zoster virus. Such patients may develop severe, life threatening infections if infected with the wild type virus.