It is the first field study conducted in the country that has intercepted the Omicron variant of the coronavirus. A large study, conducted from November 15 to December 7 by Discovery Health – South Africa’s largest private healthcare group – of over 211,000 people who tested positive for the virus, of which 78,000 attributed to the new variant based on its prevalence over the period (but not following actual sequencing).
The provisional conclusions – which therefore have yet to be scientifically reviewed – indicate that two doses of Pfizer-Biontech vaccine offer 70% protection from the risk of hospitalization, a level still high but below the 93% guaranteed against previous waves of Covid. -19. Instead, the ability to defend vaccinated people from infection is drastically lowered, dropping from 80% to 33%. The study does not provide information on the protection offered by the third dose (in South Africa only 25.7% of the population completed the two doses).
The study also showed that the proportion of seriously ill patients is lower in this early prevalence phase of Omicron than in previous waves. The risk of a Covid-19 positive adult being hospitalized is now 29% lower than in the first wave of the virus.
One factor to consider is that around 70% of the South African population according to NHS estimates has been exposed to Covid-19 since the outbreak began. There is therefore widespread immunity that may have played a role in the study’s lower hospitalization rate. Glenda Gray, president and chief executive of the South African Medical Research Council, stressed that very high levels of immunity, combined with increased vaccination coverage, may have produced a wave that appears to be “unrelated to death and hospitalization. . We do not therefore think that it is a question of the virulence of the strain, ”he added.
However, the greater contagiousness of the Omicron variant could quickly produce such a high number of infections as to cause great pressure on hospitals even in the presence of lower hospitalization rates. Hence the rush of countries to administer third doses, which according to the first indications would raise the level of protection even against Omicron.