Even as the World Health Organization (WHO) has declared that the Omicron variant reduces vaccine efficacy and spreads faster, an early study from China suggests that people previously infected with Covid-19 and those vaccinated, will have some “stronger than basic” defence against the new super mutant strain.
However, the test tube (or ‘in-vitro’, scientifically) samples of Omicron examined in this new research do show it “exceeds” all other variants in its potential capability to evade the protection gained from previous infection or vaccination.
Published in the peer-reviewed journal Emerging Microbes & Infection, the findings also suggest that although a third-dose enhancement strategy can “significantly boost immunity”, the protection from Omicron “may be compromised” – but more research is needed to better understand this.
According to lead author Youchun Wang, Senior Research Fellow from the National Institutes for Food and Drug Control in China, their results support recent findings in South Africa which highlight Omicron was “easy to evade immunity”.
“We found the large number of mutations of the Omicron variant did cause significant changes of neutralization sensitivity against people who had already had Covid,” Wang said.
“However, the average ED50 (protection level) against Omicron is still higher than the baseline, which indicates there is still some protection effect can be observed.”
But because the antibody protection – in the form of previous infection or vaccination – decreases gradually over a period of six months, Omicron “may be able to escape immunity even better”, Wang said.
For the study, a team of 11 scientists looked at 28 serum samples from patients recovering from the original strain of SARS-CoV-2. They tested these against in-vitro Omicron samples, as well as four other strains marked ‘of concern’ by the WHO (such as Delta), and two variants marked as ‘of interest’.
“This study verifies the enhanced immune escape of the Omicron variant, which sounds the alarm to the world and has important implications for the public health planning and the development of matching strategies,” Wang said.
The team said it needs to be re-evaluated whether the antibodies can still be effective against the Omicron variant.
“The exact impact to human protection may be influenced by more factors such as the infectivity of Omicron variant relative to other variants to human populations and the viral fitness of Omicron once the humans are infected,” Wang said.