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SAMRC launches a study to evaluate the effectiveness of the Moderna booster

SHERPACape Town | As South Africa is in the midst of the fifth wave of COVID-19 infections, the Sisonke Study team are once again rising to the challenge to help bolster efforts to mitigate the effects.

Led by the South African Medical Research Council (SAMRC), the Sisonke study team are launching the SHERPA Study (Sisonke Heterologous mRNA-1273 boost after prime with Ad26.COV2.S) – a study which primarily aims to evaluate the effectiveness of the heterologous mRNA-1273 (Moderna) boost against COVID-19 infections and severe COVID-19 disease among health care workers.

Sponsored by the SAMRC and co-funded by Moderna, the study aims to enroll up to 15 000 participants who received either a single or two doses of Ad26.COV2.S (JnJ) as part of the Sisonke study for health care workers. This will allow the study team to investigate the effectiveness of the Moderna COVID-19 vaccine booster against the new variants in South Africa and will provide the South African Health Products Regulatory Authority (SAHPRA) with additional data on this vaccine for potential licensing.

The heterologous boosting approach, which means that different vaccines are used for priming and boosting of the immune system, has been implemented in other countries such as the USA, Canada and Europe. Many studies have shown that this vaccination approach (especially a vector-based vaccine like Ad26.COV2.S followed by an mRNA vaccine like mRNA-1273) can elicit strong neutralizing antibody responses, and be effective in preventing COVID-19 disease.

Dr Nigel Garrett, Co-Principal Investigator of the study said: “The COVID-19 pandemic is not over yet and many people have not taken up a booster dose. The SHERPA study will provide crucial data on heterologous boosting and may help to license another effective vaccine in South Africa.” Echoing these sentiments, Co-Principal Investigator, Professor Ameena Goga emphasized that vaccination remains the key intervention to protect ourselves, our families, and vulnerable groups like pregnant and breastfeeding women against severe COVID-19. “SHERPA will provide safety and effectiveness data for heterologous boosting with the Moderna vaccine among health care workers and will inform future vaccination strategies,’ she added.

 “We are proud to support the efforts by the SAMRC to gather additional global data about the effectiveness of mRNA-1273 in a setting of unmet need,” said Jacqueline Miller, Senior Vice President, Infectious Disease Development at Moderna. “The SHERPA study highlights our commitment to supporting research in Africa, where we recently announced our intention to build a state-of-the-art mRNA facility in Kenya to serve the African continent.”

The study has also been described as an extension of several interventions by the Sisonke Study team to support the country’s vaccination efforts. As a necessary measure to maintain a healthy workforce to deal with the rising infections and hospitalisations at the time, the team was instrumental in initiating the national rollout of COVID-19 vaccination in South Africa through an implementation study that saw close to 500 000 healthcare workers getting early access to the Ad26.COV2.S vaccine. By the end of 2021, nearly 250 000 of these had received the booster shot, following the emergence of data showing the safety, immunogenicity and efficacy of a two-dose regimen.


The SHERPA Study has been launched at selected clinical research sites in South Africa, which also participated in the Sisonke study. For more information about the study, click here.

To enroll for the study, click here.

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Tendani Tsedu
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