The investigation was approved by the Health Research Ethics Committees of Stellenbosch University (C21/12/004_COVID-19) and the University of Cape Town (279/2021) and all participants provided informed consent.
Viral RNA loads in omicron variant infections have yet to be reported. It remains unknown whether the viral loads observed in our group are different from those in unvaccinated, or differently vaccinated, individuals. During wild-type SARS-CoV-2 infection, an average viral RNA load of 5·83 log10 viral RNA copies per swab was found in samples taken up to day after onset of symptoms, with a maximum of 8·85 log10 viral RNA copies per swab. In this group of individuals, an average of 6·38 log10 viral RNA copies per mL of eluted swab was detected, with the highest viral load (8·22 log10) detected on day 4 after onset of symptoms. This suggests that the individuals were infectious, in keeping with the occurrence of infection clusters sparing none of the members of the two groups.
This case series adds further evidence that, as predicted, omicron is able to evade immunity induced by mRNA vaccines in vivo.
Our study,…demonstrates insufficient prevention of symptomatic infection in otherwise healthy individuals who had received three doses of COVID-19 mRNA vaccines.
