Immunisation For The Elderly

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WE tend to identify immunisation with infants and young children, but in recent years, there has been public interest in immunisation of adults and the elderly against certain infections.   

Immunisation can protect people against harmful infections, which can lead to serious complications, including death. Immunisation uses the body’s natural defence mechanism to build resistance to specific infections.  

Immunisation and vaccination  

Many laypeople use these terms interchangeably and it may be helpful to clear some misconceptions. 

Vaccination means having a vaccine – that is actually getting the injection.   

Immunisation means both receiving a vaccine and becoming immune to a disease, as a result of being vaccinated against that disease.   

How does immunisation work?  

All forms of immunisation work in the same way. When a person is vaccinated, his body produces an immune response in the same way the body would after exposure to a disease, but without the person suffering any symptoms of the disease.   

When a person comes in contact with that disease in the future, his immune system will respond promptly to prevent the person developing the full blown disease.  

What are in vaccines?  

Vaccines contain either a very small dose of a live, but weakened form of a virus; a very small dose of killed bacteria or virus or small parts of bacteria; or a small dose of a modified toxin produced by bacteria.   

Vaccines may also contain either a small amount of preservative or a small amount of an antibiotic to preserve the vaccine. Traces of egg protein may be present in some vaccines, so please check with your doctor if you have any known allergies.  

Immunisation for the elderly  

Every year thousands of seniors suffer from influenza or pneumonia, sometimes with fatal outcomes. The combined cause-of-death category of “pneumonia and influenza” ranks as the fifth leading cause of death in the United States for people age 65 or older.   

Who should have immunisation?  

In recent years, there has been considerable evidence to suggest that immunisations against the influenza virus and the pneumococcus germ are beneficial to the elderly, especially for those with chronic lung, heart and kidney problems, diabetes mellitus, those in institutions such as nursing homes, and those who travel overseas.   

Immunisations are available for the prevention of both influenza and pneumococcal pneumonia, but very few high-risk seniors receive both vaccines.  

Seniors in the above category are at an increased risk of infection and, with few exceptions, should consider receiving an annual influenza immunisation and a one-time pneumococcal vaccine.   

In Malaysia, a recent study has shown a protective effect of the pneumococcal vaccine for those seniors performing the Haj.   

In a study conducted by Prof Ilina Isahak at five old folks homes in West Malaysia, the influenza vaccine has also been effective in reducing the flu-like symptoms amongst resident seniors.  

There are also suggestions to provide vaccinations for those who work in healthcare facilities such as nursing homes and hospitals to reduce the likelihood of health workers spreading infection amongst the old and infirm.  

Such immunisation programmes will improve the quality of resident care in the facility by preventing serious influenza outbreaks and potentially avoiding deadly pneumococcal infections for some residents. The major benefit expected from vaccination in the elderly population is a reduction of severe cases.  

Should all seniors be immunised?  

Although some experts feel that all elderly should be immunised, most studies on the influenza vaccine were conducted in the Northern Hemisphere, in temperate countries where influenza peaks of incidence occur during the winter (influenza season). In these studies, influenza is recognised as an important cause of severe disease among elderly.   

In tropical and subtropical areas, influenza viruses occur throughout the year. Small seasonal peaks may occur coinciding with the winter seasons in the northern and southern hemispheres – spread from travellers from these regions. The importance of influenza infection in tropical areas is not clearly understood, and hence few seniors consider immunisation necessary.  

The association of influenza infection and severe illness amongst seniors is inferred from the link between seasonal increase in morbidity and mortality rates of respiratory disease and detection of influenza virus. This evidence supports vaccination against influenza targeting the senior population and carried out two to four weeks before seasonal peaks.   

Seniors travelling abroad are advised to inform their doctors well in advance as to where they intend to travel as there may be a choice of two influenza vaccines (for the northern and southern hemispheres). Unfortunately, due to the “antigenic drift” of the influenza virus, annual jabs are required to confer some degree of protection.  

Seniors should appreciate that influenza infection is not the only risk factor related to outbreaks of severe respiratory disease in the elderly population. For the Haj pilgrims, it is now mandatory to receive vaccinations for influenza and meningococcus (that can cause meningitis – an inflammation of the lining of the central nervous system) germs.  

How effective is the vaccination?  

To address the issue of vaccine protection, the concepts of efficacy and effectiveness must be clarified.  

Vaccine efficacy is the percentage reduction in the incidence of a disease among vaccinated compared to unvaccinated individuals under controlled conditions, and this is often based on laboratory confirmed cases. At least three clinical trials conducted amongst elderly people found vaccine efficacy between 60% and 67% in laboratory confirmed influenza-like illness.  

Vaccine effectiveness is the percent reduction in the incidence of a disease among vaccinated compared to unvaccinated individuals under routine conditions, and may include non-influenza cases.   

An analysis of 20 studies showed that the vaccine reduced the incidence of pneumonia by 50% and death by 67%. A study conducted in the United Kingdom among seniors showed a 21% vaccine effectiveness against hospitalisations for acute respiratory disease (with no reduction in hospital admissions outside influenza seasons).   

Conclusion  

In all societies, there are usually several health issues contending for limited resources, which direct policymakers to set priorities in allocation of funds.  

Essentially there are different viewpoints (be it society, government or individuals) regarding immunisation in the elderly. Nevertheless, it would seem reasonable and judicious to suggest that “high risk” seniors (those with chronic lung, heart and kidney problems, diabetics, those in nursing homes, and those who plan to travel overseas) should consider immunisation as an insurance to maintain their health.  

(Written by Dr Philip Poi Jun Hua)