– Omicron has one “substantial” ability to evade immunity from a previous Covid contagion: this is what the first South African study on real cases revealed on the effect of the new variant of Covid-19. A fact that suggests that Omicron could cause a substantial wave of cases even in populations with high levels of antibodies.
Although only about a quarter of the South African population is fully vaccinated, immunity from natural contagion is high because the country has had several major waves of Covid. Well if the risk of reinfection in the Beta and Delta waves was lower than the first wave of cases in March 2020 (the one caused by the Wuhan strain of the virus), with the Omicron variant the risk of reinfection is 2.4 times greater than in the first wave.
This has public health implications because it means that Omicron can also spread to a population with very high levels of natural immunity. The question now is what happens in a population where vaccination rates are high. Research from the National Institutes of Health in the United States has shown that antibodies produced by Covid vaccines are more likely to recognize variations in the virus’s spike protein than those generated by natural immunity; and this could mean that people who are fully vaccinated and possibly even ‘boosted’ with the booster are able to ‘bypass’ Omicron. But it will still take weeks to find out.
Scientists have investigated nearly 2.8 million confirmed cases of Covid-19 in South Africa since March 2020 and found that 35,670 were recontact cases. Meanwhile, the World Health Organization has sent an emergency team to South Africa, in particular in the province of Gauteng, the epicenter of the variant, to better understand how it spreads.