National Blood Service study

A study published earlier this month tested 4858 blood donors in four provinces for antibodies to the SARS-CoV-2 virus. The study showed high levels of antibodies amongst African black donors indicating that over 60% of these donors had most likely been infected with the virus. A graph taken from the study shows the levels of antibodies by race and province and is set out below.

The blood samples were extracted on 7 days over the period 7 to 25 January 2021. Extrapolating the findings to the rest of the population in each province resulted in seroprevalence levels of 63% for the Eatern Cape and 52% for KwaZulu Natal. Lower seroprevalence levels were found for the Free State (46%) and the Northern Cape (32%).

It is interesting to compare the results of the study with the predictions of the NMG projection model. The cumulative infection rates from the NMG model show very similar infection levels to that of the study for the Eastern Cape (63.5%) and for the Norther Cape (30.2%) but higher levels than the study for KwaZulu Natal (62.6%) and the Free State (65.9%).

In the study, the authors point out that communities from economically depressed areas in a province may be underrepresented in the blood donor study. This could have impacted some provinces more than others.

In terms of collective immunity, one could conclude from the study results that a third wave might be less likely in the communities that are predominantly African black.




Comments

  1. NoopnrFebruary 25, 2021 at 2:13 PM

    Interestingly, Discovery mentioned a reinfection rate that seems to equate to 0.7% in their annual results just out. So still quite small and not way off NICD figures from Jan which were a little lower. So seems to continue to be quite rare.

    ReplyDelete
    Replies
    1. NoopnrMarch 2, 2021 at 10:27 AM

      Although Discovery did go on to say 'a third of people can be reinfected' without disclosing a great deal more as to how that is calculated. The latest Brazilian variant / Manaus study out today (not peer reviews) also seems to indicate significant chances of reinfection with the variant. No info on the IFR for reinfections though.

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