Thread by @SACEMAdirector

@theSANBS, @The_WCBS, and #SACEMA have released new information on SARS-CoV-2 seroprevalence among blood donors in South Africa, including in the 5 provinces for which data were not previously available. #NotYetPeerReviewed

A full preprint will be released soon.

The new data are based on samples collected in May 2021, using the same methods as described in the earlier preprint from Sykes et al:

researchsquare.com/article/rs-233…

The study was led by @Marionvermeulen with data analysis by @laurettemhlanga, Dr Eduard Grebe, and Prof Alex Welte.

The study is primarily funded by @theSANBS and @The_WCBS. #SACEMA and its researchers are funded by @dsigovza and @NRF_News.

The study used the @Roche Elecsys platform, which detects antibodies produced by natural infection that bind to the N protein of the SARS-CoV-2 virus.

My take (1/4): Overall, seroprevalence in SA appears to be around 43%. The percent of people protected by natural immunity and vaccination may be higher. The test used in this study does not detect vaccine-derived antibodies, and the estimates could reflect some antibody waning.

My take (2/4): The Delta variant dominates transmission in SA. Delta is ~2X as transmissible as the original virus and ~1.5X as transmissible as Beta. With what is likely <50% population-level immunity, we are in a similar boat to a year ago regarding transmission potential.

My take (3/4): The last 15 months have been brutal for those of us in SA, as in most of the world. The next few months will continue to try us. Vaccination brings our best hope of making COVID manageable.

My take (4/4): Please get vaccinated when you're eligible. For now, continue to mask, sanitize, distance, ventilate, and if you can #stayhome. We owe it to each other and the health workers who have worked tirelessly throughout the pandemic and still have a long way to go.

And in case you're interested in more details on transmissibility of the Delta variant, here are some useful references:

eurosurveillance.org/content/10.280… from @fcampbell_ and the @WHO Health Emergencies Team

bit.ly/react-1-round-… from @SRileyIDD and the REACT study team