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Following is a question by the Hon Law Chi-kwong and a written reply by the Secretary for Health and Welfare, Dr E K Yeoh, in the Legislative Council today (March 28):

Question :

Regarding vaccinations given to infants by the Department of Health ("DH"), will the Government inform this Council:

(a) of the respective dates when DH specified the various vaccines now given to infants;

(b) whether DH has employed improved or new strains of vaccines in the past five years; if so, of the details and the criteria adopted for determining the need to employ new vaccines; and

(c) of the number of confirmed cases of haemophilus influenzae type b infection among infants in Hong Kong in the past two years and, among them, the number of cases in which complications had been caused; whether it will consider vaccinating all infants in Hong Kong; if so, of the public expenditure required each year; if not, the reasons for that?

Answer :

Madam President,

In Hong Kong, a comprehensive immunization programme has been provided for all children for decades in line with the principles set out in the World Health Organization's (WHO) Expanded Programme on Immunization (EPI). The EPI currently recommends that all countries immunize against poliomyelitis, diphtheria, pertussis, tetanus, measles and Hepatitis B, and that places with a high incidence of tuberculosis infection should also immunize against tuberculosis.

(a) The year of introduction of various vaccines in Hong Kong's current childhood immunization programme is as follows :

Vaccine Year of Introduction

BCG Vaccine 1952

Diphtheria, Pertussis and

Tetanus Vaccine 1956

Oral Polio Vaccine 1963

Hepatitis B Vaccine 1988

Measles, Mumps and

Rubella (MMR) Vaccine (Note) 1990

Note: The Measles Vaccine was first introduced in 1967.

(b) In 1996, the two-dose MMR regime was adopted in Hong Kong with the first dose of MMR vaccine given at age one and the second dose at primary one. The decision was made having regard to experience worldwide and strong evidences that a second dose of measles vaccine can enhance the immune response.

In 1997, the strain for the mumps virus in the MMR vaccine was changed from the Urabe AM9 strain to Jeryl Lynn strain which has been shown to be associated with a much lower risk of adverse effects.

As a general principle, we will take into account the local epidemiology of the disease (such as incidence, morbidity and mortality), the effectiveness, safety and quality of the vaccine, as well as its acceptability by the public, when considering the introduction of new vaccines into the immunization programme.

(c) Local studies have shown that the nasopharyngcal carriage rate of Haemophilus influenzae b (Hib) was very low in Chinese children and that the incidence rate of invasive Hib disease in Hong Kong ranged from 0.9 to 8.3 per 100,000 children aged under 5 years, which was much lower than corresponding rates recorded elsewhere (e.g. 60-100 per 100,000 children in the United States of America and 59 per 100,000 children in Australia before introduction of Hib vaccine). The current data indicate that Hib disease is not a major public health problem in Hong Kong and we do not maintain a comprehensive record of cases of Hib disease in Hong Kong.

A polysaccharide vaccine against Hib has been available for several years but was found to be ineffective in infants. Hib conjugate vaccines have been developed recently. In view of the demonstrated safety and efficacy of the conjugate vaccine in some studies, WHO recommends that Hib vaccine be included, where appropriate to national capacities and priorities, and having consideration to the epidemiology of Hib infection in the locality, in the routine childhood immunization programme. However, in places where the burden of Hib disease is unclear, efforts should be made to evaluate the magnitude of this problem.

In view of the recommendation of WHO and the previous studies conducted locally which have shown a low incidence rate of invasive Hib disease, the Advisory Committee on Immunization (ACI) does not recommend immunization of all children in Hong Kong against Hib at present but recommends Department of Health (DH) to employ the rapid assessment tool recently developed by WHO to re-assess the local burden of Hib disease. DH is now making plans for the assessment exercise. The ACI will review the immunization programme in the light of the findings of the assessment and the experience of other places.

End/Wednesday, March 28, 2001

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