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Following is a question by the Hon Dennis Kwok and a written reply by the Secretary for Food and Health, Dr Ko Wing-man, in the Legislative Council today (April 20):
Question:
A mercury-containing organic compound, thimerosal, has been widely used as a preservative in vaccines. As thimerosal allegedly contributes to the development of autism and other neurological disorders in children, there have been concerns over the safety of vaccines containing thimerosal. In this connection, will the Government inform this Council:
(1) whether public antenatal check-up services currently include laboratory tests on the levels of mercury and other heavy metals in the blood of pregnant women; if not, of the reasons for that; if so, the respective average levels of mercury and other heavy metals found in the blood samples taken in the past 12 months, and whether the authorities have traced the sources of the mercury and other heavy metals found in the blood samples;
(2) whether public neonatal care services currently include laboratory tests on the respective levels of mercury and other heavy metals in the blood of infants; if so, of the average levels of the mercury and other heavy metals found in the blood samples taken in the past 12 months, and whether the authorities have traced the sources of the mercury and other heavy metals found in the blood samples; and
(3) whether public hospitals and health centres currently provide any mercury-free vaccines, in particular thimerosal-free vaccines, for infants; if not, of the reasons for that; if so, whether the authorities have conducted any laboratory tests on the mercury level in the blood of those infants who were injected with such vaccines; if so, of the relevant average level in the blood samples taken in the past 12 months; whether the authorities have traced the sources of the mercury found in the blood samples?
Reply:
(1) In collaboration with the obstetric department of the Hospital Authority, Maternal and Child Health Centres (MCHCs) of the Family Health Service under the Department of Health (DH) provide an antenatal shared-care programme for pregnant women to monitor their entire pregnancy and delivery process. According to the Guidelines on Antenatal Care issued by the Hong Kong College of Obstetricians and Gynaecologists, routine antenatal check-ups in public hospitals do not cover examination of the level of heavy metals (including mercury). If any symptom of heavy metal poisoning is found in a pregnant woman, the doctor will conduct suitable examinations according to her clinical condition. The antenatal services provided by MCHCs include body checks, laboratory tests, health education and specialty referrals based on clinical needs. The list of items for laboratory tests is drawn up with reference to the relevant local and overseas guidelines on antenatal services and does not cover examination of the level of heavy metals (including mercury).
The Family Health Service also provides pregnant women with health education on balanced diet and food safety to help them minimise the health risks posed to the foetus by excessive exposure to metal contaminants. The DH will use different channels including pamphlets, webpages, individual counselling and health talks to remind pregnant women to consume a balanced and nutritionally adequate diet during pregnancy. Although fish contain omega-3 fatty acids, which are beneficial to the brain and vision development of the foetus, pregnant women are advised to opt for fish that are smaller in size for consumption because large-sized predatory fish, such as shark, swordfish, marlin, alfonsino and tuna, usually contain a higher level of mercury. According to food safety principles, pregnant women should consume fish in moderation and eat from a variety of fish so as to reduce the risk.
(2) The routine check-ups in public hospitals do not cover examinations of the level of heavy metals (including mercury) for newborns. If any symptom of heavy metal poisoning is found in a newborn, the doctor will conduct suitable examinations according to clinical condition.
(3) At present, the vaccines procured by the Government under the Hong Kong Childhood Immunisation Programme, namely (i) bacillus Calmette-Guérin (BCG) vaccine; (ii) hepatitis B vaccine; (iii) Diphtheria, tetanus, acellular Pertussis and inactivated poliovirus (DTaP-IPV) vaccine; (iv) diphtheria (reduced dose), tetanus, acellular pertussis (reduced dose) and inactivated poliovirus (dTap-IPV) vaccine - booster dose; (v) pneumococcal vaccine (13-valent); (vi) measles, mumps and rubella (MMR) vaccine; and (vii) varicella vaccine, involve a total of 10 registered pharmaceutical products. None of these registered vaccines contains thiomersal (a mercury-containing preservative). Before getting a child vaccinated, healthcare personnel are required to explain the details to the child's parent/guardian or representative and seek his/her consent for the vaccination.
Given that some children may have adverse reactions to the acellular pertussis component of the 4-in-1 (DTaP-IPV or dTap-IPV) vaccine and such vaccine is contraindicated in these cases, the Government will separately provide diphtheria/tetanus vaccine or diphtheria (reduced dose)/tetanus vaccine, and poliovirus vaccine for these children. Both the diphtheria/tetanus vaccine and diphtheria (reduced dose)/tetanus vaccine contain thiomersal at a level not exceeding 50£gg/0.5 ml. At present, there is no registered alternative of these vaccines in Hong Kong which does not contain thiomersal.
The Global Advisory Committee on Vaccine Safety (the Advisory Committee) of the World Health Organization has discussed the safety of thimerosal-containing vaccines and issued a report in 2012. The Advisory Committee considers that available evidence strongly supports the use of thimerosal as a preservative for inactivated vaccines, and no safer and equally efficacious alternative has been identified for general use in vaccines.
The Government will continue to monitor the results of studies on the safety of thimerosal-containing vaccines and the supply of registered thimerosal-free vaccines in Hong Kong.
Ends/Wednesday, April 20, 2016
Issued at HKT 18:16
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