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- Initial data from the Sisonke study has shown increased protection against Omicron through booster shots.
- More than 230 000 healthcare workers have received the J&J vaccine booster shot.
- However, there were more breakthrough infections among healthcare workers than with previous variants.
Initial data from the Sisonke 2 study has shown that booster shots improve protection against the Omicron variant.
In a digital briefing on Friday, held by the national Department of Health, president of the South African Medical Research Council (SAMRC) and co-investigator of the Sisonke trial, Glenda Gray, said the booster shots had shown increased protection against hospital admission.
During the trial, 235 064 healthcare workers received a booster shot of the Johnson & Johnson (J&J) vaccine.
For the first two weeks after the booster shot, participants recorded vaccine effectiveness of 63%. This increased to 84% between 14 and 27 days, and 85% between one and two months, Gray said.
Gray added that there had been 51 493 breakthrough infections since the start of the Sisonke trial in February. Daily infections due to Omicron were three times higher than that seen with the Delta variant in the third wave, she said.
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She added that breakthrough infections mimicked findings in the general population, with symptoms appearing less severe, with lower hospital admission rates than in previous waves.
"With Omicron there was a clear and early decoupling of hospitalisation from cases," she said.
In breakthrough infections, the study found there was less likelihood of patients being admitted to ICU or needing ventilation and oxygen when compared to Delta infections.
Not as many 'admissions and deaths'
Gray added that Omicron presented more in younger people than previous variants.
The same trend was seen in the rest of the population, said the National Institute for Communicable Diseases of South Africa's (NICD) Dr Waasila Jassat.
She said during the briefing that the fourth wave had shown the decoupling between infections and hospital admissions.
This meant that deaths and admissions were not rising in proportion to infections.
Jassat said:
Hospital stays were shorter in the fourth wave compared to previous waves, said Jassat, and there was a lower percentage of cases requiring admission into ICU.
While there were lower numbers of adults admitted, there was a higher percentage of cases admitted to hospital among children.
In addition, hospital admissions appeared to be largely in those who were not vaccinated. Based on a small sample of cases, relying on self-reported data, more than 80% of hospitalisations were among unvaccinated people, said Jassat.
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