HealthHealth

Immunisation coverage of children

Author/s: Katharine Hall
Date: August 2024

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. The primary course of immunisation in the first year includes BCG, OPV 1,2 & 3, DTP-Hib 1,2 & 3, HepB 1,2 & 3, and 1st measles vaccination (usually at 9 months).

Data


Data Source Health Systems Trust (2024) “District Health Barometer” data file (derived from Department of Health’s District Health Information System – DHIS). Available at www.hst.org.za.
Note: The immunisation rates in the District Health Barometer have not been adjusted to the revised population model before 2015.

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 may be influenced by population movement in health seeking behaviour – for example, if children from one district or province are taken to a health facility in a neighbouring district or province.

The immunisation rates are also affected by national (and district-level) estimates of population size. The 2015 immunisation rate, as reported in the 2016 District Health Barometer, reflected high levels of immunisation for infants under a year, at 89.2%,2 but the population model for the country had under-estimated the number of children, Statistics South Africa subsequently revised its population model and released a new series of mid-year population estimates3 and the 2015 immunisation rate was revised downwards to 79.5%. The 2016 rate dropped to 71% after retrospective adjustment to the revised population estimates. The lower immunisation rate for that year was attributed to a global shortage of Hexavalent vaccine.4 In 2017 the immunisation rate picked up to 77%, increasing further to 82% in 2018 and 83.5% in 2019. In 2020, the immunisation rate dropped to 79.5% nationally as a result of lockdown, and as low as 61% in Limpopo. These fluctuations illustrate how the immunisation programme, which generally has high levels of compliance, is highly sensitive to disruptions in vaccine supply (as in 2016) or service delivery (as in 2020).

Immunisation rates improved again to 85.5% in 2021, dropping back slightly to 82.2% in 2022. This increase in the year following the hard lockdown, followed by a slight decline the next year, occurred across all provinces and might have been the result of a catch-up in delayed infant immunisations. When comparing the baseline immunisation rates in 2015 with those in 2022, the overall rates are quite similar despite some volatility in the intervening years. The average rate for the country was slightly higher in 2022 (82%) than in 2015 (79%).

Underlying the overall increase between 2015 and 2022 are some quite contrasting patterns across provinces. Immunisation rates over the period increased substantially in KwaZulu-Natal and, to a lesser extent, in the Eastern Cape, Free State and Mpumalanga. At the same time, immunisation rates dropped in Limpopo, the Northern and Western Cape and Gauteng.

The highest immunisation rates for 2022 were in KwaZulu-Natal (92%) and Mpumalanga (89%),while the lowest rates were in Limpopo (68%), North West (74%), and the Northern and Western Cape (both 76%).

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’ in the South African Demographic and Health Survey of 2016 were substantially lower than those recorded in the District Health Information System for the same year (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.