1. What is pneumococcal infection?
Pneumococcal infection represents a wide range of diseases caused by the bacterium Streptococcus pneumoniae (or more commonly referred as pneumococcus). While pneumococcus is a common cause of mild illnesses such as sinus or middle ear infections, it may also cause severe or even life-threatening invasive pneumococcal diseases (IPD) such as pneumonia, sepsis, and meningitis. The outcomes for IPD are usually more severe among young children and elderly persons.
2. What is Streptococcus pneumoniae / pneumococcus?
Streptococcus pneumoniae (pneumococcus) is the causative agent of pneumococcal infections. It is a Gram-positive bacterium encapsulated with polysaccharides. The difference in the composition of capsular polysaccharides constitutes to at least 90 different serotypes of pneumococci identified thus far.
Pneumococci are carried on human bodies. They are present in the respiratory tracts even in some healthy carriers. The bacteria can be transmitted via spread of droplet, direct oral contact or indirect contact with articles soiled with respiratory discharges.
4. What is the incidence rate of IPD in Hong Kong?
IPD is more common among young children and the elderly. In Hong Kong, the annual incidence of IPD ranged from 1.7 to 2.9 per 100,000 from 2007 to 2015. The incidence is higher in children younger than 5 years of age and adults 65 years of age and older.
5. How can pneumococcal infections be treated?
The treatment of pneumococcal infections usually involves the use of antibiotic(s). But there is a problem of increasing resistance of the bacterium to antibiotics, which makes prevention of pneumococcal infections important.
As there are over 90 serotypes of pneumococcus, previous infection of a serotype of pneumococcus may not confer immunity to other serotypes of pneumococcus.
One of the most effective means of preventing pneumococcal diseases is by pneumococcal vaccination. The public should also maintain good personal and environmental hygiene practices, balanced diet, regular exercise, adequate rest, and no smoking.
8. What is the relationship between influenza and pneumococcal infection?
Influenza predisposes individuals to bacterial community-acquired pneumonia. Secondary bacterial pneumonia has been an important cause of morbidity and mortality for those infected with influenza.
9. What are pneumococcal vaccines?
There are two types of pneumococcal vaccines available in the market, namely a 23-valent pneumococcal polysaccharide vaccine (23vPPV) and pneumococcal conjugate vaccines (PCV). 23vPPV consists of pneumococcal capsular polysaccharides for 23 pneumococci serotypes. PCV consists of pneumococcal capsular polysaccharides conjugated to carrier proteins. In Hong Kong, three types of PCV (PCV7, PCV10 and PCV13) consisting of antigens against seven, ten and thirteen pneumococci serotypes are registered.
Both 23vPPV and PCVs are safe and can prevent invasive pneumococcal diseases (IPD). Clinical studies indicated that PCV13 are effective against both IPD and non-invasive pneumococcal pneumonia, and have a better efficacy against non-invasive pneumococcal pneumonia when compared with 23vPPV. Nethertheless, it is worth noting that 23vPPV contains 11 additional serotypes and theoretically offers extra protection.
11. Who should get pneumococcal vaccines?
The Scientific Committee on Vaccine Preventable Diseases (SCVPD) recommends children under 2 years of age to receive PCV under the Hong Kong Childhood Immunisation Programme (HKCIP). The standard regimen includes a primary series of 3 doses at 2, 4 and 6 months and a booster dose at 12-15 months.
SCVPD recommends high-risk individuals* aged 2 or above to receive a single dose of PCV13, followed by a single dose of 23vPPV 1 year later. For those who have already received 23vPPV, a single dose of PCV13 should be administered 1 year after previous 23vPPV vaccination. For those who have already received PCV13, a single dose of 23vPPV should be administered 1 year after previous PCV13.
For elders 65 years of age and older without high risk conditions*, SCVPD recommends either a single dose of PCV13 or a single dose of 23vPPV.
*High risk conditions include:
(a) History of invasive pneumococcal disease
(b) Immunocompromised states:
- Asplenia, HIV /AIDS , primary immunodeficiency
- Immunodeficiencies related to malignancies and transplantation
- Immunodeficiencies related to use of immunosuppressive drugs / systemic steroid
(c) Chronic disease
- Chronic cardiac, pulmonary, liver or renal disease
- Diabetes mellitus or CSF leakage
(d) With cochlear implants
(Essential hypertension per se is not considered as a high risk condition)
Different factors such as age and clinical condition may affect the risk of pneumococcal disease. Patients with high-risk conditions should discuss with their attending doctors on the most appropriate vaccination regimen.
12. Why is it necessary to receive both influenza vaccine and pneumococcal vaccines?
Secondary bacterial pneumonia is an important cause of morbidity and mortality for those infected with influenza. Data from a local study shows that dual vaccination with influenza vaccine and pneumococcal vaccines can lower the risk of hospitalisation and mortality among elderly people.
13. Can pneumococcal vaccines be received together with seasonal influenza vaccine?
Yes. Both 23vPPV and PCV can be given together with other vaccines, including influenza vaccine, but they should be administered with a different syringe and at a different injection site.
14. Can pneumococcal vaccines be given prior to / after certain medical procedures?
For individuals who will undergo elective splenectomy, pneumococcal vaccines should be given at least 2 weeks before the procedures if possible. Pneumococcal vaccines should not be given during chemotherapy or radiotherapy for cancer.
15. What are the adverse events associated with pneumococcal vaccines?
Pneumococcal vaccines have been demonstrated to be safe. Common adverse reactions include slight swelling and tenderness at the injection site shortly following injection. Local reactions are more severe following a second dose but most resolve within a few days without treatment.
16. Who are not suitable to receive pneumococcal vaccines?
Severe allergic reaction following a prior dose of pneumococcal vaccine or to the vaccine component is a contraindication to further doses of vaccine.
Minor illnesses such as upper respiratory tract infections are not contraindications to vaccination. Vaccination may also be deferred until symptoms subside in case of any worry.
18. Can pneumococcal vaccines be given during pregnancy or breastfeeding?
The safety of pneumococcal vaccines during pregnancy is not known. It is not known whether the vaccine is excreted in human milk. Women who wish to receive pneumococcal vaccines should be vaccinated before pregnancy, if possible.