VII THE CHILDHOOD IMMUNISATION PROGRAMME IN SINGAPORE 7. 7

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1 VII THE CHILDHOOD IMMUNISATION PROGRAMME IN SINGAPORE IMMUNISATION PROGRAMME IN The childhood immunisation programme in Singapore offers vaccination against tuberculosis, hepatitis B, diphtheria, pertussis, tetanus (DPT), poliomyelitis, measles, mumps and rubella (MMR). Only diphtheria and measles immunisations are compulsory by law. Since 1 January 1990, the monovalent measles vaccine given to one-year-old children was replaced by the trivalent measles, mumps and rubella (MMR) vaccine. As of 1 Jan 1998, the monovalent rubella vaccine given to primary school leavers was replaced by the second dose of MMR vaccine (Table 7.1). Hepatitis B vaccination for infants born to carrier mothers was incorporated into the national childhood immunisation programme in October This was extended to all newborns through the use of Medisave since 1 September To protect those who were born before 1987, a 4-year hepatitis B immunization programme was implemented for students in secondary 3, junior college year 2, pre-university year 3, institutes of technical education, polytechnics and universities in January In addition, full-time national servicemen who were non-immune were offered hepatitis B immunization. The report does not cover BCG vaccination. This is prepared separately by the Communicable Disease Centre, Tan Tock Seng Hospital. IMPLEMENTATION OF THE IMMUNISATION PROGRAMME The vaccination programme was carried out by: (a) Restructured polyclinics of the National Healthcare Group (NHGP) and the Singapore Health Service (SingHealth); (b) School Health Service (SHS) of the Health Promotion Board and (c) Private medical practitioners. 7-1

2 Table 7.1 Recommended childhood immunisation programme, Singapore, 2002 DISEASES PRIMARY COURSE B O O S T E R D O S E S Infants (< 1 years) TUBERCULOSIS Birth - BCG without Mantoux test DIPHTHERIA* 3 months PERTUSSIS DPT (1st Dose) TETANUS 4 months DPT (2nd Dose) 5 months DPT (3rd Dose) POLIOMYELITIS* 3 months 4 months Pre-school children (1-5 years) Direct BCG if no previous vaccination 18 months DPT (1st Booster) 18 months 1st Booster Primary school students (6-12 years) 6-7 years (Primary school entrants) Direct BCG if no previous vaccination. 6-7 years (Primary school entrants) DT (2nd Booster) years (Primary school leavers) DT (3rd Booster) 6-7 years (Primary school entrants) Either: (a) Primary course for those who have never been vaccinated; or (b) 2nd Booster for those who had been vaccinated. Secondary school students (12-15 years) 5 months MEASLES/MUMPS/ RUBELLA 1 year (1st dose) years (Primary school leavers) 3rd Booster years (Primary school leavers) 2 nd dose HEPATITIS B +Birth, 1, 5-6 months 4-year ( ) hepatitis B immunization programme for Sec 3, JC year 2, centralized institutes year 3, ITEs, polytechnics and universities * When the recommended time schedule is not followed, then the time interval between the different doses should be adhered to. Interrupting the recommended schedule or delaying subsequent doses does not reduce the ultimate immunity. There is no need to restart a series regardless of the time elapsed between doses. However, to help ensure seroconversion, completion of the primary series of three doses is recommended. + HBIG (0.5 ml) given at the same time as the first dose of vaccine only for babies born to HBeAg (hepatitis B e antigen)-positive mothers. An additional dose of hepatitis B vaccine for babies born to HBsAg-positive mothers at 12 months. 7-2

3 Immunisation of pre-school children was the responsibility of the polyclinics. The target population was based on notification of births obtained from the Registrar of Births and Deaths. Follow-up home visits and telephone reminders were routinely carried out by staff nurses of the polyclinics to cover missed cases or defaulters of the programme. The SHS was responsible for the immunisation of school children. The target population was based on student population data from the Ministry of Education. NOTIFICATION The data utilised in this report was based on: (a) notifications of all immunisation carried out in pre-school children by both the public and private sectors to the Central Immunisation Registry, Health Promotion Board (notifications of diphtheria and measles immunisation are compulsory); and (b) immunisation records kept by SHS (immunisations administered in schools and at the Immunisation Clinic, Student Health Centre of the Health Promotion Board) were captured in the SHS Computerisation System. IMMUNISATION AGAINST DIPHTHERIA, TETANUS AND PERTUSSIS Infants and pre-school children 38,565 infants and pre-school children were reported to have completed their primary immunisation course in An estimated 92% of live births completed their primary course under one year of age (Table 7.2). General practitioners immunised a total of 14,885 (38.6%) children. In 2002, a total of 41,357 booster doses were given to pre-school children. It was estimated that 93.2% of children below 2 years of age were covered by the booster programme based on Jul Jun 2001 live-births (44,386) and assuming no mortality. School children For school entrants who had never been immunised, a primary course of two doses of diphtheria/tetanus (DT) vaccine was scheduled. In 2002, a total of 46,244 doses of DT vaccine were given to those who had received a booster more than two years before school entry or who had never received a booster. During the year, 93.1% of school entrants received boosters (Table 7.2). 7-3

4 Table 7.2 Diphtheria immunisation of infants, pre-school and school children, Vaccination of infants and pre-school children Vaccination of school children live completed primary course before one year of age (% live-births immunised) completed primary course (DT/DPT) boosters given Estimated % of pre-school children given booster doses school entrants received primary immunisation boosters given* given a booster & primary course (% school entrants immunised) ,605 43,026 (94.3) 43,696 45, , ,331 44,331 (89.0) ,193 40,440 (93.9) 41,311 45, , ,276 45,276 (89.8) ,631 40,216 (90.4) 40,966 37, , ,527 46,527 (91.4) ,450 (94.4) 39,611 38, , ,725 46,725 (92.6) ,864 37,595 (92.0) 38,565 41, , ,244 46,244 (93.1) Mean 43,614 40,003 (91.7) 40,830 41, , ,820 45,820 Source: Department of Statistics, Singapore * Figures include: (i) those given a booster dose at school entry; and (ii) those given a booster dose less than two years before school entry 7-4

5 In 2001, there were 3,433 (6.9%) missed vaccinees among school entrants. 761 (22.2%) of these were given boosters in For school entrants during the period , an average of 35% of the missed vaccinees were covered (Table 7.3). In 2002, 95.7% of the primary school leavers were given DT boosters (Table 7.4). From , the coverage remained high, with an average of 93.9%. Table 7.3 Coverage of missed primary I vaccinees followed up in primary II for vaccination against diphtheria, missed primary one vacinees % of missed vaccinees over total new school entrants received primary immunisation in the following year received boosters in the following year % of missed vaccinees covered* % of missed vaccinees immunised over total school entrants* , , , , , , , , Mean 4, , * Coverage by School Health Service and does not include booster immunisations done by private practitioners. Table 7.4 Diphtheria and tetanus boosters given to primary school leavers years of age, Total primary VI children boosters given % of primary VI children covered ,153 37, ,111 42, ,554 52, ,987 47, ,258 50, Mean 49,213 46,

6 IMMUNISATION AGAINST POLIOMYELITIS Infants and pre-school children 38,622 infants and pre-school children were reported to have completed their primary immunisation course in ,615 children (92% of live births) completed their primary course before one year of age (Table 7.5). 15,043 (38.9%) children were immunised by private practitioners. In 2002, a total of 41,148 boosters were given to children below two years of age. An estimated 92.7% of children below 2 years of age were covered under the booster programme based on Jul Jun 2001 live-births and assuming no mortality. School children In 2002, 46,052 (92.7%) school entrants were given boosters (Table 7.5). In 2001, 3,605 (7.3%) of the school entrants missed their booster doses. Of these children, 755 (20.9%) were immunised in 2002 (Table 7.6). The coverage of missed Primary I vaccinees over the period constituted 2.9% of the total school entrants. During the year, 50,905 (95.6%) primary school leavers received booster doses (Table 7.7). MEASLES/MUMPS/RUBELLA IMMUNISATION Infants and pre-school children In 2002, a total of 39,954 children below two years of age were immunised against measles, mumps and rubella giving a coverage of 90% based on Jun live-births (44,386) and assuming no mortality (Table 7.8). Most immunisations were carried out by restructured polyclinics, (62%) and private clinics and hospitals (37.4%). School children There were no missed vaccinees among school entrants. In 2002, the number of primary school leavers immunized was 50,700 (95.2% coverage). 7-6

7 Table 7.5 Poliomyelitis immunisation of infants, pre-school and school children, Vaccination of infants and pre-school children Vaccination of school children live completed primary course before one year of age (% live-births immunised) completed primary course boosters given Estimated % of pre-school children given booster doses school entrants received primary immunisation boosters given* given a booster and primary course (% school entrants immunised) ,605 43,084 (94.5) 43,794 45, , ,191 44,191 (88.7) ,193 41,096 (95.4) 41,717 45, , ,035 45,035 (89.3) ,631 40,094 (90.2) 40,914 37, , ,397 46,397 (91.1) ,775 38,220 (91.5) 39,255 38, , ,527 46,527 (92.7) ,615 (92.0) 38,662 41, , ,052 46,052 (92.7) Mean 43,614 40,022 (91.8) 40,860 41, , ,640 45,640 Source: Department of Statistics, Singapore. * Figures include: (i) those given a booster dose at school entry; and (ii) those given a booster dose less than two years before school entry. 7-7

8 Table 7.6 Coverage of missed primary I vaccinees followed up in primary II for vaccination against poliomyelitis, missed primary one vaccinees % of missed vaccinees over total new school entrants received primary immunisation in the following year received boosters in the following year % of missed vaccinees covered % of missed vaccinees immunised over total school entrants* , , , , , , , Mean 4, , * Coverage by School Health Service and does not include booster immunisations done by private practitioners. Table 7.7 Poliomyelitis boosters given to primary school leavers years of age, Total number of students boosters given % of students vaccinated ,153 37, ,111 42, ,554 52, ,987 47, ,258 50, Mean 49,213 46,

9 1999 Table 7.8 Measles/mumps/rubella immunisation, Private School Restructured Restructured clinics/ Health Total polyclinics hospitals hospitals Service <2 yrs 29,006 10, ,187 >2 yrs ,310* 45,120 TOTAL 29,617 11, ,310 85, <2 yrs 25,859 12, ,751 >2 yrs ,952 * 54,009 TOTAL 26,772 12, ,952 92, <2 yrs 25,697 15, ,903 >2 yrs ,465 * 48,212 TOTAL 26, <2 yrs 24,787 14, ,954 >2 yrs 789 2, ,265 * 54,824 TOTAL 25,576 17, ,268 94,778 * second dose of MMR vaccine for primary 6 students HEPATITIS B VACCINATION A total of 13,847 blood samples of antenatal women were screened at the Kandang Kerbau Women s and Children s Hospital for HBsAg and HBeAg in Of these, 325 (2.3%) were HBsAg positive and 82 (0.6%) HBeAg positive. In 2002, of 34,269 babies delivered in Kandang Kerbau Women s and Children s Hospital, Singapore General Hospital, National University Hospital, Mt Alvernia Hospital, Thomson Medical Centre and Gleneagles Hospital, 29,733 (86.8%) were vaccinated at birth (Table 7.9). 39,492 infants were reported to have completed their primary course of hepatitis B immunization below one year of age in Most immunizations were carried out by doctors at restructured polyclinics (23,990 or 60.7%) and by doctors in restructured hospitals and private practitioners (15,502 or 39.3%). The overall coverage rate for babies who have completed the full course of vaccination under one year of age remained high at 94.5% based on the live births in Jan Hepatitis B vaccination programme in secondary schools, junior colleges and centralised institutes A 4-year hepatitis B immunization programme is being carried out for secondary 3, junior college 2 and pre-university 3 students each year from 2001 to Consent was first obtained from parents for their child to participate in pre-immunisation blood screening. Each school would be visited four times within 7-9

10 Table 7.9 Hepatitis B vaccination of newborns in Kandang Kerbau Women s & Children s Hospital, Singapore General Hospital, National University Hospital, Thomson Medical Centre and Gleneagles Hospital, 2002 Kandang Kerbau Women s & Children s Hospital Singapore General Hospital National University Hospital Mount Alvernia Hospital Thomson Medical Centre Gleneagles Hospital Month live births vaccinated % live births vaccinated % live births vaccinated % live births vaccinated % live births vaccinated % live births vaccinated % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total 15,111 12, ,905 1, ,746 2, ,632 4, ,624 4, ,250 3, Note: No returns received from East Shore Hospital and Mount Elizabeth Hospital. 7-10

11 the calendar year (once for blood screening, three times for each dose of the vaccine at fixed intervals of one and five months). Students who missed the blood screening and immunization would be referred to the Student Health Centre. In ,382 students were screened for hepatitis B immune status. Of these, 19,249 (36.1%) of these students were tested non-immune and required hepatitis B immunization. 17,247 (89.6%) students completed a full course of 3 doses of hepatitis B vaccination. EFFECTIVENESS OF THE IMMUNISATION PROGRAMME The effectiveness of the childhood immunisation programme against poliomyelitis and diphtheria is clearly shown in Figs. 7.1 and 7.2. In 2002, no indigenous case of diphtheria, poliomyelitis, pertussis and neonatal tetanus was reported. With the implementation of the catch-up measles vaccination programme using the MMR vaccine in 1997, and the introduction of the second dose of MMR vaccine to all primary six school children in 1998, the incidence of measles remained low. It decreased sharply from 1,413 cases in 1997 to 57 in 2002 (Fig. 7.3). Rubella incidence decreased from 242 cases in 2001 to 152 in No outbreak was reported. No termination of pregnancy was carried out on account of rubella infection (Table 7.10). One case of congenital rubella was reported in a Malay infant born to a 27-year old woman who had not been vaccinated against rubella. The baby was tested positive for rubella IgM antibody at birth and had bilateral congenital glaucoma, left cataract, hearing loss and patent ductus arteriosis. Following a resurgence of mumps in 1998, due to poor protection conferred by the Rubini strain of the MMR vaccine, the disease incidence had returned to normal with 1,090 cases reported in 2002 (Table 7.11). The incidence of indigenous acute hepatitis B declined from 243 cases (9.5 per 100,000) in 1985 to 63 cases (1.9 per 100,000) in 2002 (Fig.7.4). No cases in children < 15 years had been reported since

12 Figure 7.1 Incidence per 100,000 population from poliomyelitis and immunisation coverage rates in Singapore, Poliovirus vaccine type 2 to 200,000 children National immunisation programme Rate per 100,000 population Coverage rate in percent Incidence per 100,000 population Immunisation coverage rate (Infants) Immunisation coverage rate (Primary school entrants) OTHER003/CMH/

13 Figure 7.2 Incidence per 100,000 population from diphtheria and immunisation coverage rates in Singapore, Health education campaigns Immunisation compulsory Rate per 100,000 population C o verage rate in percent Incidence per 100,000 population Immunisation coverage rate (Infants) Immunisation coverage rate (Primary school entrants) OTHER003/CMH/

14 Figure 7.3 Impact of the catch-up MMR vaccination programme and introduction of second dose of MMR vaccine on the incidence of reported measles cases in Singapore, "Catch-up" MMR vaccination programme for all secondary and pre-university students, Jul - Nov 1997 Re porte d cases Confirm e d cases* cases nd dose of MMR vaccine introduced Enhanced epidemiological surveillance implemented 20 0 Week * Measles-specific IgM antibody positive MMR002/CMH/ Figure 7.4 Incidence per 100,000 population from acute hepatitis B+ and immunisation coverage rates*, Singapore, Hepatitis B vaccination for infants born to carrier mothers (Oct 1985) 120 Rate per 100,000 population Hepatitis B vaccination for all newborns (Sep 1987) Cov erage rate in percent Rate per 100,000 Cov erage rate + Indigenous cases * For children < 1 year old Hep-B001/CMH/

15 Table 7.10 abortions done for rubella infection, Total no. of abortions done for rubella infection* abortions % , , , , , , , , , , , , , , , , , , , , *Not all the rubella infections were serologically confirmed. (Source: Abortion Annual Statistical Report, Ministry of Health Medical Audit and Accreditation Unit, Ministry of Health) 7-15

16 Table 7.11 Reported diphtheria, poliomyelitis, measles, acute hepatitis B, neonatal tetanus, pertussis, congenital rubella and childhood tuberculous meningitis in Singapore, Diphtheria Poliomyelitis Measles Mumpsφ Rubellaφ Acute hepatitis Neonatal tetanus Congenital rubella# Childhood tuberculous meningitis## (2) 1 (1) 1, (4) 2 (2) (2) 2, (2) (1) (1) (1) (1) , , , * 1++ 2* 2* (1) * 4 (1)+++ 2* 2* , * 2++ 0* 2* , * 1+ 0* 0* ,384 (28) * 1++ 2* 1* , (1) * , * 1+ 2* 0* , * 0 1* 1* ( ) Imported cases. φ Notifiable with effect from April Indigenous cases below 15 years of All pertussis cases reported prior to 1986 were based on clinically diagnosed cases seen at the Communicable Disease Centre. + Based on clinically diagnosed cases ++ Based on laboratory confirmed cases. +++ Based on laboratory confirmed and clinically diagnosed cases. # Cases diagnosed in Toa Payoh Hospital, Kandang Kerbau Women s & Children s Hospital, Alexandra Hospital, Tan Tock Seng Hospital, Singapore General Hospital and National University Hospital. ## Below 10 years of age. Source: Annual Reports, Maternal & Child Health Service, Ministry of Health. * Source: Central Claims Processing System, Ministry of Health 7-16