Pediatric Preventable Pulmonary Diseases - An Overview

Introduction

Childhood vaccination through the expanded program on immunization (EPI) is one of the most cost-effective medical interventions to check the spread of infectious diseases. Early vaccination has significantly reduced childhood morbidity and mortality and contributed to achieving the millennial development goal of decreasing the mortality rate of children under five by two-thirds by 2015.

Public-private partnerships like the global alliance for vaccines and immunization (GAVI) have helped develop advanced research programs to formulate new vaccines. Their main focus is to expand access by implementing immunization programs in developing countries to underused and new vaccines, like the hepatitis B and Haemophilus influenza type B (Hib) vaccines. However, the costlier newer vaccines challenge the previous notion of the cost-effectiveness of vaccination. Further studies on the cost-effectiveness of immunization are particularly important to determine the number of resources needed to develop better immunization programs and use the available resources most optimally.

Despite all the efforts to educate the population, immunization rates in preschool children have decreased in several developed countries compared to developing countries, thus resulting in epidemics of several vaccine-preventable diseases. The common pulmonary infections prevented by immunization are those caused by:

• Bordetella pertussis.

• Streptococcus pneumonia.

• Haemophilus influenza type-B.

• Corynebacterium diphtheria.

• Measles virus.

• Influenza virus.

The growing probability of epidemics and the increase in immunocompromised children have necessitated more studies in prevention strategies. This article will discuss the pulmonary infections preventable by vaccines and the current recommendations for childhood immunization.

Which are the Pediatric Preventable Pulmonary Diseases?

Diseases affecting the pulmonary system are the major cause of morbidity and mortality worldwide, with more susceptibility for infants and young children. The spectrum ranges from acute infectious diseases to chronic non-communicable diseases. Pneumonia is the leading cause of childhood mortality, taking 1.3 million lives annually, most of which are avoidable. There is a close relationship between pediatric and adult respiratory diseases. Unattended early childhood respiratory infections often lead to chronic diseases in adulthood. Childhood immunization can significantly reduce the incidence and severity of some pulmonary diseases. Respiratory diseases are a global burden, and an upscaled implementation of implicit strategies is required for the prevention and management of respiratory diseases, improving global health and erasing the inequalities in healthcare globally.

The preventable respiratory infections and the recommended vaccinations are given below:

• Pertussis: Also known as whooping cough, pertussis is a bacterial infection caused by bordetella pertussis. It is transmitted from one individual to the other through respiratory secretions and occurs worldwide. In developing countries, most of the cases are seen among school children. Clinically the affected children are presented with a running nose for an initial seven to ten days, which progresses to paroxysmal and spasmodic cough. In approximately ten percent of affected infants, clinical pneumonia is observed. The vaccines used for pertussis are of two types:

  • Diphtheria, tetanus, and pertussis (DTaP) vaccines.

  • Tetanus, diphtheria, and pertussis vaccine (Tdap).

  • Children younger than seven years receive DTaP, and adults and older children receive Tdap.

Studies indicate that in countries with less than 70 percent vaccination coverage, the proportion of susceptible children at the age of one year is 30 percent compared to one percent in countries with 70 percent vaccination coverage. However, by age 15, the susceptibility is 100 percent in both cases. Therefore a vaccine efficacy of 80 percent is suggested for disease prevention and 95 percent for preventing deaths.

• Pneumonia: It is an acute respiratory infection of the lungs. The lung alveoli (air sacs in the lungs) are filled with fluid and puss, making breathing difficult. It is the largest cause of death in children and accounts for 14 % of deaths of children below five years and 22 % among children aged one to five. Several infectious agents cause them, and the prevention and management depend on the causative agents. Vaccinating against Hemophilus influenza type-B, measles, pertussis, and pneumococcus is the most efficient way to prevent pneumonia in children.

• Diphtheria: Diphtheria is a bacterial infection caused by the toxin-producing strains of corynebacterium diphtheria transmitted by respiratory droplets. Before the widespread vaccination,more than five percent of people suffered from diphtheria. Infected children are presented with weakness, sore throat, mild fever, and swollen glands of the neck. The toxins produced by the bacteria kill the tissues of the lungs that later form into a thick grey coating in the throat and nose called the pseudomembrane. The vaccines for diphtheria are the same as that for pertussis, namely DTaP, and Tdap. The vaccination schedule for diphtheria is

One dose of DTaP in each of the following ages:

1. First Dose: Two months.

2. Second Dose: Four months.

3. Third Dose: Six months.

4. Fourth Dose: 15 to 18 months.

5. Fifth Dose: Four to six years.

And one dose of Tdap at the age of 11 or 12 years. In addition, booster doses are needed to keep up the protection.

• Haemophilus Influenza type-B (HIB): This is a bacterial infection affecting the upper respiratory tract of children. The infection is transmitted through respiratory droplets and causes serious systemic infections. The organism primarily causes pneumonia and meningitis in young children and is a global public health concern. Vaccination is the single public health tool that can reduce the global burden of the disease. Deaths caused by Hemophilus influenza type B are mainly due to meningitis and pneumonia. Studies reveal that HIB is responsible for approximately 20 % of deaths caused by lower respiratory tract infections in the absence of vaccination. The mortality rate among children in developed countries is one percent compared to 12 percent in underdeveloped countries. Hemophilus influenza type B vaccine are liquid preparation of poly ribosyl ribitol phosphate (PRP) capsular polysaccharide oh HIB linked to a carrier protein. The recommended vaccination schedule is single shots at two, four, six, and eighteen months.

• Measles: It is an acute viral infection of the respiratory tract. Complications of the disease include pneumonia, encephalitis (brain inflammation caused by an infection), and blindness. Children of immune mothers are protected against clinical infection until five to nine months of age by the passively acquired antibodies from the immune mothers. Recent studies show a mortality rate of three percent for the disease. The vaccine for measles is MMR (measles, mumps, rubella) vaccine protects against measles, mumps, and rubella. The recommended vaccination schedule for children is

1. First Dose: 12 to 15 months.

2. Second Dose: 4 to 6 years.

Conclusion

From the above discussions, it is clear that vaccination is the safest and most cost-effective intervention for preventing infectious pulmonary diseases. It has significant roles in preventing morbidity and mortality from childhood pulmonary infections and will help achieve the child health millennium development goals.