Vaccines for the elderly need to be introduced into the immunization program in India

Abstract

The population in India over age 60 years has tripled in the past 50 years and will relentlessly increase in the near future. According to census 2011, elderly people were 8.1% of the total population, and the projections for population over 60 years over the next 4 censuses are 133 million (2021) expanding to 301 million (2051). In developing countries, the elderly have suffered from both communicable and non-communicable diseases. Moreover, advancing age is associated with decreased immunity along with physiological changes, and poor health leads to increased risk of infectious diseases. Infections such as pneumococcal, influenza, tetanus, and zoster are more common among elderly population. These infections are major causes of morbidity and mortality among the elderly and are responsible for a large number of deaths and hospitalizations. Communicable diseases like influenza and pneumonia are the fifth leading cause of death among elderly persons. A study reported the incidence of nosocomial infections in geriatric patients in India to be ~20%. Pseudomonas aeruginosa was the most common microbe associated with Urinary Tract Infection, while Staphylococcus aureus was frequently observed in cases of pneumonia among hospitalized elderly population. In India, because of many reasons, preventive care for elderly persons is often neglected. Among the many infections to which the elderly are prone, some can be prevented by administration of appropriate vaccines. Vaccination of the elderly is one of the most effective means of preventing disease, disability, and death from infectious diseases.

Keywords: :

• infection
• pneumonia
• disability
• death
• vaccine

The worldwide aging population is one of the most discussed global phenomena. Countries with a large population like India have a large number of people aged 60 y or more. The population over age 60 has tripled during the past 50 y in India, and will relentlessly increase in the near future. According to census 2001, older people were 7.7% of the total population, which increased to 8.14% in census 2011. The projections for population over 60 in the next 4 censuses are: 133 million (2021), 179 million (2031), 236 million (2041), and 301 million (2051).^1,2

The elderly population in many countries is facing several problems of which deteriorating health is the most important. In developing countries, the elderly have suffered from both communicable and non-communicable diseases. Moreover, advancing age is associated with decreased immunity along with physiological changes and poor health, which lead to increased risk of infectious diseases. Immunization of the elderly is one of the most effective means of preventing disease, disability, and death from infectious diseases. The elderly population has been immunized or exposed to many disorders before they reach to old age. Even then, they still need immunizations.

Infections including pneumococcal, influenza, tetanus, and herpes zoster are more common among the elderly population. These infections are major causes of morbidity and mortality among the elderly and are responsible for a large number of hospitalizations. Communicable diseases such as influenza and pneumonia are the fifth leading cause of death among elderly persons.³ The elderly population also has been shown to have an increased risk of hospital-acquired infections. A study reported that the incidence in India of nosocomial infections in geriatric patients is ~20%. Pseudomonas aeruginosa was the most common microbe associated with Urinary Tract Infection while Staphylococcus aureus was reported in ~20% of cases of pneumonia among hospitalized elderly population.⁴

A study conducted in New Delhi among hospitalized patients for community-acquired pneumonia showed that those >50 y of age had a mortality rate nearly 2.5-fold higher than patients <50 y. The study reports that S. pneumoniae was the commonest identified bacteria. Another study from Puducherry India also reported that S. pneumoniae was the most common bacteria responsible for community-acquired acute bacterial meningitis among elderly population. Because of the increasing proportion of the elderly population, the emergence of antibiotic-resistant strains of bacteria such as S. pneumoniae has increased the public health impact of infections in the elderly.⁵ Infections such as pneumococcal, in more severe forms, also may invade the bloodstream or the fluid surrounding the brain, causing bloodstream infections or meningitis respectively. Pneumococcal diseases are mainly seen in young children or older adults. The elderly are especially at risk of getting seriously ill and dying from this disease. Globally, 3 people die every minute due to pneumococcal diseases. Those >60 y are at a significant higher risk for worse outcomes of an episode of pneumococcal disease, with higher chances of development of complications.⁶ Globally, pneumococcal disease accounts for the largest number of cases of vaccine-preventable morbidity and mortality. The US Centers for Disease Control and Prevention (CDC) recommends that all elderly should receive a single dose of pneumococcal polysaccharide vaccine. Revaccination is indicated 6 y after the first dose for those at highest risk of fatal pneumococcal disease, such as asplenic patients, those under long-term corticosteroid therapy, etc. Pneumococcal conjugate vaccine is now approved in India for those >50 y for the prevention of pneumonia and invasive pneumococcal disease caused by 13 pneumococcal serotypes.⁷

Influenza can seriously affect populations of all ages, but the highest risk of complications occurs among the elderly. Seasonal influenza is an acute viral infection caused by influenza virus. There are 3 types of seasonal influenza viruses—A, B, and C. Type A influenza viruses are further classified into subtypes according to combination of various virus surface proteins. Among many subtypes of influenza A viruses, influenza A (H1N1) and A (H3N2) subtypes circulate among humans. Influenza viruses circulate worldwide. Type C influenza cases occur much less frequently than A and B, which is why only influenza A and B virus antigens are included in seasonal influenza vaccines. The burden for influenza has been well studied in the US as compared with India. In India and other south-east Asian countries, there is lack of exact data relating to the impact of influenza. In the US, 80–90% of deaths during influenza epidemics occur in the elderly. The rates of hospitalization and death are increasing as the population ages. The emergence of pandemic strains and the opportunity for new strains to emerge make it likely that there is an unrecognized burden of influenza in south-east Asian countries.⁵

The most effective way to prevent influenza and/or severe outcomes from the illness is vaccination. Safe and effective vaccines are available and have been used for more than 60 y. Among healthy elderly, influenza vaccine can provide a reasonable level of protection. However among the elderly, influenza vaccine may be less effective in preventing illness but may reduce severity of disease and incidence of complications and deaths. The World Health Organization (WHO) recommends annual vaccination for the elderly. Vaccination is most effective when circulating viruses are well-matched with vaccine virus strains. Trivalent influenza vaccine is available and WHO recommends existing licensed vaccines containing the 2 A subtypes H3N2 and H1N1 and one type B virus.⁸ The vaccine confers a 60–90% rate of sero-protection in children and adults, but lower levels for elderly whose waning immune systems mount a weaker response to vaccination. Studies conducted worldwide have reported variable results regarding the efficacy of the influenza vaccine.⁹

Tetanus is another infection whose incidence is higher among the elderly than adults and children. This might be due to elderly subjects not only lacking immunity but are also being liable to more injuries. The disease normally affects unimmunized or partially immunized people, and risk increases with age. Children in India are protected by DPT vaccine, but immunity against tetanus wanes over time, leaving older adults susceptible to infection. Antibody concentrations are low in people over 60, especially women.¹⁰ Titers of antibodies to tetanus toxoid are inadequate to ensure protection in about half of people >65 y, who might represent an inadequately immunized segment of the society because of poor access to primary health care. All elderly people should have completed a primary immunization schedule with diphtheria and tetanus toxoid, and thereafter a booster dose is required every 10 y. For all older people who were never vaccinated against tetanus, a primary series of 3 doses is recommended; after which a booster dose is recommended every 10 y.¹¹ In developed countries like the US, 47% of the 34 cases reported in 2004 were among those over 60. 94% of person who contract tetanus in the US are not up to date on tetanus vaccination or never received the primary series.¹²

Another common morbidity among elderly population is herpes zoster. Chickenpox as a primary infection caused by varicella zoster virus (VZV). Latent VZV infection can reactivate as herpes zoster or shingles. As age advances, cell-mediated immune responses (CMI) to VZV decline, with resultant increased incidence of reactivation as herpes zoster among older people. Approximately 25% of people suffer herpes zoster during their lifetime.¹³ The most debilitating complication of herpes zoster is post-herpetic neuralgia. Both the incidence and the duration of post herpetic neuralgia are directly related to increasing age.¹⁴ Children are vaccination with varicella vaccine. The elderly can be vaccinated with zoster vaccine, which is the same vaccine as varicella vaccine but with a much higher level of vaccine virus. The zoster vaccine is not 100% effective in preventing reactivation as herpes zoster. However, cases of herpes zoster and post-herpetic neuralgia after vaccination are less frequent and less morbid than those who had not received the vaccine. The zoster vaccine prevented post-herpetic neuralgia to a greater extent among the age 70 or more years.¹⁵ Vaccination against herpes zoster also improved the quality of life among older person by preventing of acute pain and post-herpetic neuralgia related with this disease. People over 60 should receive one dose of zoster vaccine regardless of previous history of chickenpox or herpes zoster.¹⁶ This vaccine is administered subcutaneously and contraindicated in person with active, untreated tuberculosis and in immunocompromised adults such as those with leukemia, lymphoma, or generalized malignancy and in patients receiving chemotherapy, radiation, and large doses of corticosteroids.

In India, for many reasons, preventive care for the elderly is often neglected. Among the many infections to which the elderly are prone, some can be prevented by administration of appropriate vaccines. Ironically, there is no national immunization schedule for the elderly population in India. Vaccination in the elderly appears to be safe and generally effective depending on the vaccine. Vaccines such as pneumococcal, influenza, zoster, and tetanus for older people need to be introduced into national immunization program in India.

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

10.4161/hv.29254