Vaccination is one of the most important medical advances yet remains controversial. News headlines distract us from the important benefits for individuals and communities and focus on the small or potential harm for individuals. Most concern relates to children but in Australia, 91% of children meet vaccination recommendations whilst in adults the rate is low, around 51%. Pneumococcal vaccination for adults remains low and much lower than for influenza (47% versus 71.6% in over 65 respectively).
With the Australian guidelines, the 23-valent pneumococcal polysaccharide vaccine (23vPPV) is provided free for adults over 65, for Aboriginal and Torres Strait Islander adults over 50 (repeated once after five years) and adults with medical problems (more complex recommendations, see schedule). In these adults, invasive pneumococcal disease (IPD), has a high mortality, with, for example, a 16% mortality from pneumococcal pneumonia even in healthy elderly people. So, why do we not use it?
Low vaccination may be because of pessimism about whether it works or about the impact (“pneumococcus only accounts for 20% of pneumonias”) and confusion due to changing recommendations (single or repeated doses).
Does it work?
Results vary but a Cochrane review (2013) based on randomised controlled trials found overall protective efficacy of 74% against IPD and 52% effectiveness in older adults. The results were less clear for pneumonia overall or IPD in patients with at risk medical conditions, though observational studies supported use in the latter.
How long does it last? Studies show a 23vPPV vaccine effectiveness against IPD in adults of 48% within two years but insignificant after five years. In healthy adults with no risk factors, effectiveness was higher at 65% at two years and remained for longer. Common adverse effects were mild local swelling, redness, pain and a low fever, worse on a second dose. Only one dose is now recommended for well elderly people.
Data shows the introduction of the 13-valent pneumococcal conjugate vaccine (13vPCV) in children resulted in a reduction in adults of disease from the serotypes contained in the vaccine (herd cover). Subsequently, the introduction of the 23vPPV (containing an additional 11 serotypes) in adults resulted in further falls in illness from those serotypes, but the serotypes not covered expanded. As most disease is due to serotypes in the 13vPCV, the current debate is whether 13vPCV should replace 23vPPV in adults.
Influenza and pneumococcal infections are often combined. New research from South Australia, published in Nature Microbiology, trialled whole inactivated vaccines (which may resolve what serotypes to include) with influenza A and pneumococcus, co-administered in mice and showed the presence of both enhanced the response to each of them. So maybe in the future we will be using different types of vaccines in combination. Till then, keep following the Guidelines.
- Compared to children, adult vaccination rates are low.
- Vaccination is effective in reducing invasive pneumococcal disease in adults
- Follow the current Guidelines
References available on request.
Questions? Contact the editor.
Author competing interests: nil relevant disclosures.
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