Stats SA has defended the integrity of its population estimates, which the health department said earlier this week may have skewed its estimates of childhood vaccination coverage. Calculating immunisation coverage requires accurate figures for the number of babies vaccinated and the size of the tar…
Stats SA has defended the integrity of its population estimates, which the health department said earlier this week may have skewed its estimates of childhood vaccination coverage. Calculating immunisation coverage requires accurate figures for the number of babies vaccinated and the size of the target population. On Wednesday, statistician-general Risenga Maluleke said Stats SA stood by the accuracy of its published statistics, including the census and the mid-year population estimates.
The mid-year population estimates are derived from the census conducted in 2002, which had a historically high under-count of 31%. It was criticised by UCT demographers for a host of anomalies and several municipalities challenged its estimates of their populations. "This is … not the first time Stats SA's population figures have been questioned and the nature of the questioning itself illustrates why they should be trusted," Maluleke said.
"Some municipalities have argued the figures are too low; others have argued they are too high. A private institution has separately claimed that the country's true population is significantly higher than what Stats SA has reported," he said. "If the statistician-general were to revise official population figures each time a different interest group asserted they were wrong, in different and often contradictory directions, the independence and methodological soundness on which official statistics are built ― and that the country relies on ― would be lost," he said.
Public health experts in Tshwane, Cape Town and Johannesburg have expressed scepticism over the health department's vaccination coverage figures. Not only was there no evidence of a surge in hospital admissions of unvaccinated babies and toddlers, but health workers have been unable to identify significant numbers of "zero dose" babies who are completely unvaccinated, said Tshwane district paediatrician Ute Feucht.
"Our immunisation programme has certainly not collapsed. They (vaccines) are all in stock, they are free and they are accessible," Feucht said. Wits professor of vaccinology Shabir Madhi said earlier this week that there had been no notable increase in unvaccinated children being admitted to hospital.
Stats SA defends population data as vaccine coverage figures questioned
Stellenbosch University professor of public health Hassan Mahomed said the national health department's data was problematic, as academic research conducted in the Western Cape had found higher immunisation rates. Nevertheless, the fact that there were outbreaks of vaccine-preventable diseases, such as measles, indicated concerning gaps in coverage, he said.
The reliability of the mid-year population estimates has also been questioned by Neva Makgetla, senior economist at Trade & Industrial Policy Strategies, who pointed to a widening divergence between these data and the number of live births registered by the home affairs department. The mid-year population estimates for babies under the age of one increased from 1.06-million to 1.15-million between 2020 and 2024, while the number of registered births fell from 1.02-million to 799,000 over this period, Makgetla said.
The health department's deputy director-general for child and maternal health, Nonhlanhla Ndlovu, said that work was under way to try and determine an appropriate denominator for the vaccination coverage calculations, but it was important not to lose sight of the fact that any outbreak of a vaccine-preventable illness was cause for concern. "We are seeing them even in adults. That tells us there is a break (down) in herd immunity," she said. The emergence of adult cases of diphtheria was particularly worrying, she said.
