Pneumococcal Disease: Prevention & Treatment
Pneumococcal diseases, which include pneumonia, meningitis, and sepsis caused by the bacteria Streptococcus pneumoniae, are the leading cause of vaccine-preventable deaths among children under age five worldwide.
However, most cases of pneumococcal diseases are preventable - with existing tools, such as vaccines - are treatable. The challenge is to ensure that the most vulnerable children have easy, affordable access to these life-saving interventions. UNICEF estimates that only half of children with pneumonia are taken to an appropriate healthcare provider, and fewer than one in five receive antibiotics.
Prevention of pneumococcal disease before it occurs is key
Prevention saves lives, and spares children, their families, and their communities undue suffering
Determining the cause of pneumonia is challenging. Pneumonia is most often diagnosed clinically by symptoms that may include fever, cough and fast or difficult breathing. It is difficult for providers to distinguish between bacterial and viral causes of pneumonia because the clinical symptoms are often similar. This can make appropriate treatment of pneumonia difficult. Radiography and laboratory tests can be helpful in confirming pneumonia and determining the organism causing it. However, use of chest x-ray, blood culture, and other tests is limited by cost and technical challenges in many areas of the world. Furthermore, although pneumonia may be caused by bacteria, it is often not found in the blood.
In addition to the heavy emotional toll of illness, treating pneumococcal disease can cause serious financial difficulties for families and communities, contributing to the cycle of poverty. The costs of illness include: direct medical costs of illness; non-medical direct costs; and productivity costs. Further, treatment may be inadequate to prevent devastating sequelae of the disease (e.g. deafness from pneumococcal meningitis).
Despite these tremendous challenges, there is good news. Low-tech, cost-effective solutions exist to protect children against pneumococcal disease and prevent the disease before it occurs:
- Adequate nutrition helps to ensure a well-functioning immune system to protect children from pneumococcal diseases, as well as other illnesses. Children who are undernourished are at greater risk of suffering death or disability during childhood than those who receive adequate nutrition. In fact, children who are underweight are four times more likely to die of pneumonia than children who are normal weight.
- Exclusive breastfeeding during the first six months of life is a key component of adequate nutrition. Infants who are exclusively breastfed have a lower risk of infection and severe disease than those who lack this important source of nutrition. Children who are not breastfed are twice as likely to die of pneumonia before age 18 months compared to children who are breastfed.
- Pneumococcal conjugate vaccines are a well-tolerated and effective option for preventing pneumococcal diseases among children, as well as others in the community. By preventing disease, pneumococcal vaccines also reduce the need for antibiotics, the inappropriate use of which can create resistant strains of bacteria.
Vaccination is a well-tolerated and effective option for preventing pneumococcal disease
Historically, vaccination has proven to be a safe, cost-effective option for dramatically reducing death and disability associated with many childhood diseases, such as measles and polio. Today, safe, well-tolerated pneumococcal conjugate vaccines exist that can save millions of young lives from pneumococcal-related death and disability.
How pneumococcal vaccines work
When a person's immune system first comes in contact with the pneumococcal bacteria, it does not immediately recognize the threat, and is slow to mount a response. This response lag gives bacteria the chance to cause a life-threatening illness, especially in young children and the elderly. If a person is exposed to the same strain of pneumococcus a second time, the immune system immediately recognizes the threat and reacts swiftly to eliminate the bacteria, often before it can even cause illness.
When a person is vaccinated against pneumococcal disease, they are injected with small parts of killed bacteria, which create an “immune memory” for the bacteria. These killed bacteria cannot cause disease. Later, if the vaccinated individual encounters live pneumococcal bacteria, the immune system will recognize the bacteria and neutralize it so the person doesn’t get sick.
When a large proportion of a population receives a given vaccine (such as the pneumococcal vaccine), transmission of the disease to others is reduced. Unvaccinated individuals coming in contact with vaccinated individuals therefore have a lower chance of becoming infected with the organism. This phenomenon is called “herd immunity.”
Different vaccines target different types of pneumococcal bacteria. There are over 90 types, or “serotypes” of pneumococcus. Many serotypes do not cause severe disease. An estimated 88% of global disease is caused by just 23 of the 90 serotypes. Eleven serotypes account for more than 80% of disease in children under age five. A vaccine’s “valency” refers to the number of bacterial serotypes it targets.
Some pneumococcal serotypes are particularly resistant to antibiotics. Giving antibiotics unnecessarily to treat a viral infection can contribute to the emergence of antibiotic resistance. This makes it harder and more costly to treat pneumococcal infections. That is why use of vaccines to prevent pneumococcal disease before it occurs is critically important.
Three main types of pneumococcal vaccines
1) 23-valent pneumococcal polysaccharide vaccine (PPV23)
This vaccine is used in adults and immunocompromised children over age two years. It contains killed portions of sugars, or “polysaccharides” from 23 serotypes of pneumococcal bacteria. But this vaccine is not effective in children younger than two years of age, as children under age two have naïve immune systems, and they are unable to recognize the polysaccharide used in the PPV vaccine.
2) Pneumococcal conjugate vaccine (PCV10 and PCV13)
Conjugate vaccines have been available since 2000. The 10-valent conjugate vaccine (PCV10) and the 13-valent conjugate vaccine (PCV13), available since 2009 and 2010, respectively, are replacing the earlier 7-valent conjugate vaccine (PCV7). PCV10 targets ten serotypes (1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, 23F). PCV13 targets 13 serotypes (the PCV10 types plus 3, 6A and 19A).
Both PCV10 and PCV13 are also used in infants and children from 6 weeks to 5 years of age. In addition, PCV13 is also used in adults over 50 years of age. The PCV vaccine contains polysaccharides attached, or "conjugated" to protein that is more easily recognizable by the naive immune system in young children. The PCV effectively “tricks” the young immune system into recognizing the polysaccharide and providing protection against certain types of pneumococcus. These conjugated vaccines produce a stronger immune response and works more effectively than polysaccharide vaccines. However, the current PCV vaccines do not cover as many serotypes as the PPV vaccines because they are more complicated to develop and manufacture.
Pneumococcal conjugate vaccines have many advantages:
- Well-tolerated in young infants and adults
- Well-tolerated in people who are HIV-positive
- Can be administered with other vaccines, and on the same schedule as the diphtheria-tetanus-pertussis (DTP) vaccine
- Proven safe and effective in millions of children
- Can help control the growing problem of antibiotic-resistant pneumococcal disease
- May help protect others through herd immunity
Different serotypes of pneumococcus have different regional distributions. The serotypes included in PCV10 and PCV13 account for approximately 70-90% of invasive pneumococcal disease (IPD) in each geographic region.
Pneumococcal Disease Treatment
Preventing pneumococcal disease in the first place is critical to improving child survival and health. However, appropriate treatment can also save lives and minimize suffering.
Antibiotics are the mainstay of pneumococcal disease treatment
The treatment for pneumococcal disease is prompt, appropriate antibiotic therapy. These antibiotics often cost less than one dollar per day. The type of antibiotic, route of administration (e.g. oral or intravenous), and duration of treatment depends on several factors:
- Clinical syndrome (pneumonia, meningitis, sepsis, otitis media)
- Severity of diseases
- Age of child
- Local patterns of antimicrobial resistance
In addition, treatment providers may have to consider other aspects of the local setting, such as the presence of high-risk groups, including undernourished or HIV-positive children.
Many children do not receive appropriate treatment for pneumococcal disease
Antibiotics can be life-saving in cases of infections caused by pneumococcal bacteria. It can sometimes be difficult, however, for healthcare providers to distinguish between infections caused by bacteria compared to other organisms, such as viruses or parasites. For example, in some countries, particularly in Africa, children with pneumonia are sometimes misdiagnosed as having malaria. In these cases, children may never receive potentially life-saving antibiotics, or their treatment may be delayed until the disease becomes more severe. There are several additional reasons why children with pneumococcal disease, particularly pneumococcal pneumonia, may not receive appropriate treatment:
- Parents and caregivers may not recognize pneumococcal disease symptoms in a child and/or know to take the child to a health provider
- They may face barriers to accessing appropriate care for a child with suspected pneumococcal disease, such as cost of treatment and distance to a health center
- Families may mistrust the health system, and may prefer to seek advice from other unqualified individuals
- Healthcare providers may misdiagnose a child with pneumococcal disease and therefore fail to administer appropriate treatment
Antibiotic resistance is an increasing concern
Giving antibiotics unnecessarily to treat a viral infection can contribute to the emergence of antibiotic resistance. Pneumococcal bacteria are increasingly becoming resistant to common antibiotics, such as penicillin, thus making it harder and more costly to treat these pneumococcal infections.
Treatment can be costly for families and communities
In addition to the heavy emotional toll of illness, pneumococcal disease can cause serious financial difficulties for families and communities, contributing to the cycle of poverty. The costs of illness include:
- Direct medical costs of illness (e.g. hospital costs, medical personnel time, diagnostics and medications)
- Non-medical direct costs (e.g. transportation to healthcare facilities, food while hospitalized)
- Productivity costs (e.g. lost work time for family members who must care for ill children)
Further, treatment may be inadequate to prevent devastating sequelae of the disease (e.g. deafness from pneumococcal meningitis). And time is of the essence. Delays in treatment may increase the chance of disability and death.