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Feature Article

Immunisation: it’s not just for kids

LUCY DENG, RYAN MACDOUGALL, Kristine Macartney
OPEN ACCESS

Adults over 50 years of age should receive a tetanus booster, provided they have had three prior doses and have not received a tetanus-containing vaccine in the previous 10 years. This can be given as dTpa to also provide protection against pertussis. Adults of any age who have a tetanus-prone wound, potentially including injuries sustained around the house or garden, should receive a booster dose of either dTpa or diphtheria–tetanus vaccine (dT) if more than five years have elapsed since their previous dose of a tetanus-containing vaccine.

Influenza

Annual influenza vaccination is recommended for any person aged 6 months and over who would like to reduce their risk of influenza infection. It is included in the NIP for all people aged 65 years and over, and for Indigenous Australians, pregnant women (for both maternal and early infant protection) and people with at-risk medical conditions as listed in the Handbook.21 Workplace-based programs, particularly for healthcare workers, may also provide influenza vaccination for employees.

The current quadrivalent influenza vaccines have now replaced the trivalent vaccines used for decades previously. Quadrivalent vaccines are inactivated vaccines that contain two influenza A virus and two influenza B virus strains, with the strains used determined annually based on global influenza epidemiology.

Although the estimated efficacy of influenza vaccine is only around 50%, its cost-effectiveness in offsetting annual influenza disease and in reducing healthcare-associated costs is well established in the older population.22-25 Accumulating evidence suggests that immunity begins to wane three to four months following vaccination and vaccine effectiveness depends on vaccine similarity to the circulating viral strains; yearly revaccination is the best way to achieve optimal protection.26

Further details on seasonal influenza vaccines available in Australia and their use can be found in the NCIRS online fact sheet ‘Influenza vaccines for Australians’ (Box 3).

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Pneumococcal disease

The 23-valent pneumococcal polysaccharide vaccine (23vPPV) is included in the NIP for all non-Indigenous adults aged 65 years and over, Indigenous adults aged 15 to 49 years with medical risk factors and all Indigenous adults aged 50 years and over, with a booster dose for Indigenous adults five years following the first vaccination.

The 13-valent pneumococcal conjugated vaccine (13vPCV) has been registered for use in children since 2010 (included in the NIP since July 2011), and registered for use in adults aged 50 years and over since October 2011. This conjugated vaccine has the polysaccharide of each respective pneumococcal serotype linked to a carrier protein; this generates a more durable immune response, immunological memory and reduction in nasal carriage of the pneumococcus bacterium (Streptococcus pneumoniae), although covering fewer pneumococcal strains compared with the polysaccharide vaccine.

13vPCV is currently recommended for adults with medical condition(s) associated with increased risk of invasive pneumococcal disease, in addition to extra doses of 23vPPV.4 A large randomised double-blind placebo-controlled trial of 13vPCV in adults in the Netherlands showed significant vaccine efficacies for the prevention of vaccine-type community-acquired pneumococcal pneumonia and of invasive pneumococcal disease (46% and 75%, respectively).27 However, the number of cases of invasive pneumococcal disease has been declining in Australia since 2011, probably as a result of herd immunity following the introduction of 13vPCV for infants.28 Publication of updated recommendations from the analysis of the efficacy of 13vPCV compared with 23vPPV in adults is expected soon.

Measles, mumps, rubella (MMR)

Adults who were born during or after 1966 should have received two doses of measles–mumps–rubella (MMR) vaccine (a live attenuated vaccine) as they are likely to lack natural immunity. Some adults in this age group are not immune to these diseases because vaccine coverage was low when they were children and they may have missed being vaccinated in the Measles Control Campaign in the 1990s for primary school-aged children or the subsequent Young Adult Measles Control Campaign,in 2001 for those aged 18 to 30 years.29 Over 60% of all measles notifications between 2008 and 2011 were in people aged 15 to 49 years.30 Outbreaks have also been linked to virus imported from nonimmune young-adult travellers to endemic regions.31

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Although overall rubella notifications have remained low, the highest average annual rates of rubella notifications from 2008 to 2012 were in men aged 30 to 39 years and women aged 20 to 29 years.32 Vaccination against rubella is particularly important in women of child-bearing age before pregnancy, to prevent fetal infection and congenital rubella syndrome.

Mumps cases have been on the rise nationwide in recent years. In particular, there has been a large outbreak in Western Australia, primarily affecting Aboriginal adolescents in regional and remote areas.33 This further underpins the importance of ensuring high levels of two-dose MMR vaccination. All young adults should have their medical records checked for receipt of two doses of MMR vaccine, and be vaccinated (or have serological testing) if there is any doubt that past vaccination occurred. MMR vaccination for adults is not included in the NIP but is funded by some states and territories.

Meningococcal disease

There are three types of meningococcal vaccines available in Australia, covering the five most common (A, B, C, W-135, Y) of the 13 known serogroups of the meningococcus bacterium, Neisseria meningitidis. The two conjugate vaccines – meningococcal C conjugate vaccine (MenCCV) and quadrivalent (ACWY) meningococcal conjugate vaccines (4vMenCV) – contain meningococcal serogroup antigens conjugated to a carrier protein. The recombinant multicomponent meningococcal B vaccine (MenBV) contains four major protein antigens common to multiple meningococcal serogroup B strains. MenCCV is currently the only meningococcal vaccine included in the NIP, given to children at 12 months. The previously widely used quadrivalent polysaccharide vaccines have now been withdrawn from the market in Australia as they are less immunogenic than the quadrivalent conjugate vaccines, despite being less costly and still available in other countries.

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Dr Deng is the Immunisation Fellow at the National Centre for Immunisation Research & Surveillance (NCIRS), Westmead; and a General Paediatric Advanced Trainee at The Children’s Hospital at Westmead, Sydney. Mr MacDougall is the Regional Infection Prevention and Control Specialist at Public Health Ontario, Toronto, Ontario, Canada. Associate Professor Macartney is the Deputy Director of the National Centre for Immunisation Research & Surveillance (NCIRS), Westmead; Staff Specialist in Infectious Disease and Microbiology at The Children’s Hospital at Westmead; and Associate Professor in the Discipline of Paediatrics and Child Health at the University of Sydney, Sydney, NSW.