For the calculation of cost-effectiveness ratios, it has been assumed that the current deaths and disabilities from these vaccine preventable diseases represent the loss of health with immunization. By using the incidence rates without immunization, total cases in absence of immunization has been derived. The calculation of effectiveness for immunization also assumes that the average DALYs lost per case in 2000 remains constant for cases happening in absence of immunization.
In Turkey, immunization services are delivered through the health centers and midwives. The recommended schedule of immunization by the Expanded Programme on Immunization (EPI) is to immunize children against BCG at age 2 months, DPT and Polio at two, three and four months, hepatitis B at birth, two and nine months. Measles vaccination is given at nine months of age. In the system, DPT and Polio boosters are given at age 16 to 24 months and BCG, Polio and measles boosters are given at age 7 years. Diphtheria and tetanus shots are given at ages 7 years and 12 years of age.
It appears that Turkey does not have a well-defined vitamin A distribution system. The EPI is not responsible for vitamin A distribution. However, it is still possible to add the cost of vitamin A with the total immunization cost. Vitamin A deficiency is not a significant public health concern in Turkey. If a distribution system is organized, it is probably adequate to target about 30% of children (poorer regions and provinces). Given the number of under-5 children, total doses of vitamin A needed will be about 3.95 million doses (6.58 million children x 30% x 2 doses/year). The price of 3.95 million vitamin A tablets or capsules were 0.24 million USD (0.062$*3.95).The price of vitamin A capsules vary widely depending upon the make of the vitamin (brand name). For our calculations, we have chosen the lowest cost
Vitamin A brand (capsule packet of 60 capsules at a cost of TL 1,338,200). Cost per capsule becomes $0.019 for the lowest cost brand. Using this price, cost of 3.95 million vitamin A tablets or capsules becomes US$ 0.07 million ($0.019*3.95).
Table 93 presents the actual number of vaccine doses delivered in the year 2000 in Turkey. The number of doses used for vaccinating children of age one year or more has been estimated using the estimated number of children in the age groups and an average coverage assumption. The coverage is assumed to be about 90% of the coverage rate of the final dose of the vaccine. For example, in 2000, the coverage rate for BCG was 77%. At 7 years, we assume that the coverage rate will decline further to (77*0.9)=69.3% .
Table 93. Doses Delivered In A Year In Turkey (year 2000)
Cov Less than 1 1-2 years 7 years 12 years
(for >=1 yr old) Number (Y=2000) 1,244,675 2,670,073 1,689,155 1,719,664 BCG 69% 1,047,784 ---- 1,170,584 ---- DPT 72% 3,398,531 1,922,453 ---- ---- Polio 72% 3,385,931 1,922,453 ---- ---- Measles 73% 1,102,328 --- 1,233,083 ---- Hep B 72% 2,688,498 ---- ---- ---- TT2 50% 844,577 653,472 TOTAL 11,623,072 3,844,906 2,403,667 653,472 * The number of doses by immunization agent obtained from MOH data
Research, Planning and Coordination Council, Health Statistics, 2002, www.saglik.gov.tr
In Turkey, total number of vaccinations delivered should be about 18,525,117 in 2000.
Cost of delivering immunization at the health center level is about TL 2 486 513 (From the cost data of health centers, US $2.10 per dose in 2001 exchange rate 1 USD=1,186,400). In addition to health center level costs, the EPI incurs additional costs for managing the program, maintaining the cold chain and distribution of vaccines to health centers. Using the data from Global Alliance for Vaccine Initiative (GAVI) (13), the facility level cost should be around 62% of total cost of immunization. It is assumed that the cost of distributing vaccines is 15% and maintaining the cold chain is another 15% of total (15% of 62 implies adding 9.3 points for transportation and distribution costs and 9.3 points for cold chain). At the same time, within the total EPI costs, 25% are assumed to be general (if we multiply (62+9.3+9.3) by 1.25, we get approximately 100). This implies that adding these numbers is consistent with the average immunization cost found by GAVI. Adjusting for all these additional costs, cost
per dose becomes TL 3.69 million (US$3.11). Therefore, the total cost of EPI becomes US$57.6 million for whole Turkey. Detailed calculations are given below:
Cost per dose at health center TL 2 486 513 Transportation 9.3%
Cold chain 9.3%
Transportation + Cold Chain (9.3 + 9.3 = 18.6% ) TL 2 486 513 x 1.186 = 2 949 004
Administrative cost is additional 25% = 2 949 004 TL * 1,25 = 3 686 256 TL Cost of immunization = 3 686 256 TL or 3.11 US$
The assumption is that 80% of the immunizations are delivered at the health center level. Thus, the calculations are based on the health center data. If health policy makers want to deliver immunizations by including MCHFP clinics, cost per dose becomes
1 171 084 TL (US $ 0.99), and including transportation, cold chain and administrative costs the cost per dose becomes TL 1 736 132 (US $ 1.46) and the total cost of EPI becomes 27.11 million US dollars.
To estimate the effectiveness of the EPI program, we have calculated the number of cases with and without immunization, given the immunization coverage rate and the probability of infection if not immunized. The ratios of diseased children without immunization were derived from different sources. In the non-immunized situation, the incidence of polio was taken from the data of Bart et al. (14). Other rates were taken from Khan and Yodar (15).
However, in Turkey, TT2 coverage has been reported at only 50%. If the TT2 coverage rate is only 50% , the above probability of tetanus without immunization will imply a much higher number than the number reported in DALY calculations. In DALY calculations, the TT cases is reported as 242, implying a probability of only 0.0003 rather than .005, the probability often reported in the literature. In the calculation below, we have used the lower probability of tetanus infection as reported in the DALY tables. In reality, almost all children are likely to get measles if not immunized. However, the health effect of most measles cases is so small that we can ignore these cases. Only the more serious types of episodes (measles) are considered here.
Table 94 reports the numbers for TT vaccinations. We started from the total population of the country in the year 2000. To find the effect of TT immunization, we need the number of births
that happened in the country in 2000. Number of live births in the year was derived by multiplying the population by Crude Birth Rate (CBR). The CBR of Turkey in 2000 was about 22.2 per thousand population and if we use this ratio, the number of live births become (67803.927*22.2) or 1,505,247. If we use the lower incidence of tetanus implied by the DALY calculations, the number of tetanus cases becomes 452 without immunization. The current number of cases shows the situation after the adoption of the intervention. With 50% coverage this number falls to 242.
Table 94. Calculation of Saved DALYs for TT2
TT2+
Coverage Rate 50%
Population 67,803,927
# of live births in 2000 1,505,247
Tetanus cases without immunization 452
Tetanus cases with immunization 242
DALYs lost in 2000 (from BOD) 3754
DALYs per case 21.54
DALYs without immunization (452*21.54) 9,733
DALYs with immunization (prediction) 3754
DALYs saved 5979 = (9733-3754)
In table 95, we again derive the number of live births from the size of total population. Using the perinatal mortality rate, it is possible to estimate the number of infants dying by age one month. Because infants do not receive some immunizations before completing their second month, it is important to calculate the number of infants surviving after one month of age. To find the number of infants surviving beyond the first month, we assume that the infant mortality is distributed over the 11 months equally. According to Jamison et. al. (5), number of pertussis cases without immunization usually varies from 1-5% of under 15 years-old children. If we adjust the numbers for under-1 (6.13% of under 15 years-old population, under 1 years old in Turkey) the equivalent incidence rate should be in between 16-81%. The mid- value of the range will be considered here (48% ). Note that the equivalent incidence rate is obtained only to project the number of cases expected without immunization. This does not indicate the number of cases expected among less than one year old children.
Table 95. Calculation of Saved DALYs for Pertussis
PERTUSSIS
Coverage Rate 83 %
Population 67,803,927
# of live births in 2000 1,505,247
# of deaths within 1 month 49,071
# of alive at age 1 month 1,456,176
Infant mortality rate 0.0419
Number of deaths of infants 63,070
# of deaths in 2-11 months 13,999
# of deaths in first 2 months of life 50,344
# alive at age 2 month 1,454,904
cases without immunization
(48% of under 1, excluding the deaths
occurring before 30 days, see the text) 698,353 (1,454,904*0.48)
Cases with immunization (from BOD tab) 40,682
DALYs lost (from BOD table) 25,894
DALYs per case
0.636
(25,894/40,682) DALYs without immunization
444,152
(0.636*698,353) DALYs saved
418,258
(444,152-25,894)
Table 96 shows the calculations for measles vaccination. Without immunization, the number of measles cases will be quite high, almost all unprotected children. In the book DCP (5), the incidence of measles in unvaccinated population (as well as vaccinated population) is given. The incidence rate is assumed by the authors to be 38 per thousand population (page 175, second paragraph). This is a very high rate of incidence and unlikely to be valid for a population group that is mostly protected due to earlier infection. Since almost all unvaccinated and unprotected children are likely to experience measles (15), it can be assumed that 75% of infants will be exposed. With 75% exposure, all these children will be infected with measles. Only about a quarter of these cases are likely to be of the more severe type of measles.
In table 97, we have considered the incidence of polio as 2.7% of infants. This number is taken from the study by Bart et al. (14).
Table 96. Calculation of Saved DALYs for Measles
Measles
Coverage Rate 84 %
Population 67,803,927
# of live births in 2000 1,505,247
# alive at age 2 months (see table above) 1,454,904
cases without immunization (75% of infants alive at age 2 months):
1,454,904*0.75 1,091,178 Severe cases (25% of total cases): 1,091,178*0.25 272,794
cases with immunization (from BOD, measles template) 30,501
DALYs (from BOD table) 51,083
DALYs per case=(51,083/30,501) 1.6748
DALYs without immunization (272,794*1.6748) 456,875
DALYs with immunization 51,083
DALYs saved (456,875-51,083) 405,792
Table 97. Calculation of Saved DALYs for Polio
Polio
Coverage Rate 83 %
Population 67,803,927
# of live births in 2000 1,505,247
cases without immunization (2.76% of total live births according to Bert et al.) 41,545 cases with immunization (from BOD table reports DALY but no cases.
Assumed 1,200 1,200
DALYs (from BOD table) 2,442
DALYs per case 2.035
DALYs without immunization (2.035*41,545) 84,544
DALYs saved (84,544-2442) 82,102
Adding all the DALYs saved from these four major diseases, the EPI have saved about 912,131 years. Therefore, cost per DALY saved becomes $63.10 ($57.6 million/912 131 DALYs saved).