HealthHealth

Immunisation coverage of children

Author/s: Katharine Hall
Date: November 2019

Definition

This indicator shows the percentage of children younger than one year who are fully immunised. “Full immunisation” refers to children having received all the required doses of vaccines given in the first year of life.

Data

Graph
Data Source Department of Health (2019) District Health Information System. Reported in: Massyn N, Pillay Y & Padarath A (eds) District Health Barometer 2017/2018. Durban: Health Systems Trust.
Notes
  1. The immunisation rate is the percentage of all children in the target area under one year who complete their basic course of immunisation during the month (annualised). A basic course includes BCG, three doses of STaP-IPV-Hib, and 1st measles vaccine.
  2. The numerator is the children fully immunised under 1 year while the denominator is the target population under 1 year.
  3. Reporting periods run from mid-year to mid-year.
Immunisation is one of the most effective preventative health care interventions to prevent serious illnesses and death in young children. It entails giving injections or drops to young children that protect them against potentially life-threatening illnesses such as tuberculosis, polio, hepatitis and measles. South Africa has an up-to-date immunisation programme, in keeping with world standards. The Expanded Programme on Immunisation (EPI) in South Africa was last updated in 2015.
The revised EPI schedule for public health facilities providing services to children in the first year of life includes immunisation at birth, and then at 6 weeks, 10 weeks, 14 weeks and 9 months.1 Thus, by the time of their first birthday, all babies should have visited a health facility at least four times after birth for immunisation services, and these immunisations should be recorded in the child’s Road-to-Health booklet.

Immunisation coverage serves as a good indicator of the extent to which young children access primary health care services. Immunisation coverage is also a proxy for the extent to which children access other health services, as the immunisation schedule provides a point of contact for identifying other health problems and for scheduling preventative child health interventions. Examples of these are the vitamin A supplementation programme, developmental screening, and prophylaxis for babies born to HIV-positive mothers.

Immunisation rates are tracked in the District Health Information System and are calculated as the number of children who have received complete immunisation divided by the child population within that district. The percentages obtained in this way will be influenced by population movement in health seeking behaviour – for example, if children from one district are taken to a health facility in a neighbouring district. This has sometimes resulted in some districts, and even provinces, reporting immunisation rates of over 100%.

The immunisation rates are also affected by national (and district-level) estimates of population size. The 2015/16 immunisation rate, as reported in the 2017 District Health Barometer, reflected high levels of immunisation for infants under a year, at 89.2%.2 Since then, Statistics South Africa revised its model to derive the mid-year population estimates, and it was found that the number of children in the country had previously been underestimated.3 The 2015/16 immunisation rate was revised downwards to 79.5%. The 2016/17 rate had dropped even before the new population estimates were released, to 82.3% and after retrospective adjustment to the revised population estimates, the rate for that year was calculated at 71.2%. The lower immunisation rate for that year was attributed to a global shortage of Hexavalent vaccine.4 In 2017/18 the immunisation rate was estimated at 77%. The immunisation rates in the District Health Barometer have not been adjusted retrospectively before 2015, and so it is not possible to determine long-term trends in immunisation uptake.

The highest immunisation rates for 2017/18 were in Mpumalanga (90%), the Northern Cape (85%), KwaZulu-Natal (82%) and the Western Cape (81%) – all of which exceeded the national average of 77%. Eastern Cape and North West had the lowest immunisation rate (69%).

The challenge of national and provincial aggregates is that they can mask differences between districts and hide areas with low coverage. District coverage is available in the 2017/18 District Health Barometer where 29 of the 52 districts show coverage below the national average. Coverage for individual districts demonstrates significant inter-district inequities in service access for young children – ranging from a low coverage rate of 56% in the Sarah Baartman District Municipality of the Eastern Cape, to 98% in the eThekwini Metropolitan Municipality in KwaZulu-Natal. Low coverage rates are concentrated mainly in poorer districts, where health needs may be greatest.

Effective immunisation requires high levels of coverage to achieve a certain level of immunity within the broader community. This is known as ‘herd immunity’ and it means that, if immunisation coverage has reached a high enough level, even the most vulnerable who have not been immunised in that community will be protected – including young children and those with low immunity.
Even though immunisation is freely available, and the goal is for it to be universal, it is voluntary and there is growing evidence that some parents choose not to immunise their children. A “worldwide increase in vaccine hesitancy and refusal” has been described as a threat to the public health achievements in controlling and preventing infectious diseases.5 At a country level, vaccine sentiment and voluntary compliance is inversely correlated with socio-economic status (i.e. compliance is lower in wealthy countries than in poorer ones).6 

The completion rates for “basic immunisation” (BCG, three doses of STaP-IPV-Hib, and one dose of measles vaccine) in the South African Demographic and Health Survey of 2016 were substantially lower than those recorded in the District Health Information System (at 61%, compared with 77%). The reason for this discrepancy is not clear, but it is important to note that compliance was highest in the poorest wealth quintile (66%) while the richest quintile was lower, at 60%7. This suggests an inverse correlation between socio-economic status and immunisation in South Africa, a highly unequal country.
 
1 Dlamini N (2019) Chapter 8: Immunisation. In: Massyn N, Pillay Y & Padarath A (eds) District Health Barometer 2017/2018. Durban: Health Systems Trust.

2 Massyn N, Padarath A, Peer N, Day C (eds) (2018) District Health Barometer 2016/17. Durban: Health Systems Trust. 

3 See “Demography” on this website, and Hall K, Sambu W, Almeleh C, Mabaso K, Giese S & Proudlock P (2019) South African Early Childhood Review 2019. Cape Town: Children’s Institute, University of Cape Town and Ilifa Labantwana.

4 See Dlamini (2019) above.

5 Verelst F, Kessels R, Delva W, Beutels P & Willem L (2019) Drivers of vaccine decision-making in South Africa: A discrete choice experiment. Vaccine 37(15), pp. 2079-2089.

6 Verelst (2019) above.
 
7 National Department of Health, Statistics South Africa, South African Medical Research Council and ICF (2017) South African Demographic & Health Survey 2016: Key Indicators. Pretoria and Rockville, Maryland: NDOH, Stats SA, SAMRC & ICF.
 
This indicator is derived from its numerator, that is, the number of children under the age of one year who are fully immunised, and its denominator, that is, the total child population under the age of one year.
The best available routine information on immunisation coverage is from the District Health Infiormation System (DHIS) of the Department of Health, as reported by the Health Systems Trust in the District Health Barometer. Immunisation coverage is derived from clinic records and reflects the proportion of all children under one year old in a target area who complete a primary course of immunisation. Notes on data quality in the Barometer suggest some errors in the data from specific health facilities and districts. Some of these data issues are resolved, for instance by removing outliers. 
 
This indicator is also very sensitive to the denominator, which is the total population of children under the age of one. Inaccuracies in the denominator may result in over- or under-estimation of immunisation coverage. A factor that may contribute to the inaccuracy of the denominator data is the high population mobility, where influx of children into an area is not added to the total under-one child population, and which may result in immunisation coverage rates of over 100%. 
 
Despite these challenges, the availability and accuracy of immunisation data seem to have improved over time and the rates provided by the District Health Barometer give reasonable estimates of immunisation coverage for purposes of monitoring child health service performance.