One of the earliest, peer-reviewed studies looking into the Omicron variant of COVID-19, published this week, suggests that people previously infected with COVID, and those vaccinated, will have some, “stronger than basic” defence against this new strain of concern.
However, the test tube (or ‘in-vitro’, scientifically) samples of Omicron examined in this latest research do show it “exceeds” all other variants in its potential capability to evade the protection gained from previous infection or vaccination.
Published in 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.
Reporting on this very early study, lead author Youchun Wang, Senior Research Fellow from the National Institutes for Food and Drug Control in China, says their results support recent findings in South Africa that highlight Omicron has “easy to evade immunity”.
“We found the large number of mutations of the Omicron variant did cause significant changes of neutralisation sensitivity against people who had already had COVID,” Wang says. “However, the average ED50 (protection level) against Omicron is still higher than the baseline, which indicated there is still some protection effect that can be observed.”
Wang, former chairman of Medical Virology and vice chairman of the Medical Microbiology and Immunology of the Chinese Medical Association, does adds caution though.
He says that 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”.
Plus, his team’s paper predicts that while “a third-dose enhancement strategy can significantly boost immunity”, the “protection from Omicron may be compromised”.
The expert 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 World Health Organization (such as Delta), and two variants marked as ‘of interest’.
“This study verifies the enhanced immune escape of 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 summarises.
Now, the team states that more research, carried out not just in-vitro but in real-world studies, is urgently needed to better understand Omicron. And, specifically, whether it can “escape from the vaccine elicited immunity to cause more severe disease and death”.
“It needs to be re-evaluated whether the antibodies can still be effective against the Omicron variant,” the authors state.
“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.
“More population studies, including the level of immune protection and symptoms among people infected with Omicron, are needed to fully establish the global impact of Omicron to the control of the COVID-19 pandemic.”
The major caveat of this study is that it is in-vitro in nature and that it used pseudotyped (manufactured) viruses. However, previous studies have used in-vitro as an established measure of “good correlation” and the current vaccine literature “has established that the in vitro neutralisation assays are good predictors of vaccine protection efficacy and real-world vaccine effectiveness”.
Therefore, the authors state, their data “may well predict the potential reduction of vaccine protection against the new Omicron variant”.
Study details
The significant immune escape of pseudotyped SARS-CoV-2 Variant Omicron
Li Zhang, Qianqian Li, Ziteng Liang, Tao Li, Shuo Liu, Qianqian Cui, Jianhui Nie, Qian Wu, Xiaowang Qu, Weijin Huang, Youchun Wang.
Published in Emerging Microbes & Infections on 10 December 2021
Summary
The emergence of Omicron has brought new challenges to fight against SARS-CoV-2. A large number of mutations in the Spike protein suggest that its susceptibility to immune protection elicited by the existing COVID-19 infection and vaccines may be altered.
In this study, we constructed the pseudotyped SARS-CoV-2 variant Omicron. The sensitivity of 28 serum samples from COVID-19 convalescent patients infected with SARS-CoV-2 original strain was tested against pseudotyped Omicron as well as the other viruses of concern (VOCs, Alpha, Beta, Gamma, Delta) and viruses of interest (VOIs, Lambda, Mu).
Our results indicated that the mean neutralisation ED50 of these sera against Omicron decreased to 66，which is about 8.4 folds compared to the D614G reference strain (ED50 = 556), whereas the neutralisation activity of other VOC and VOI pseudotyped viruses decreased only about 1.2-4.5 folds.
The finding from our in vitro assay suggest that Omicron variant may lead to more significant escape from immune protection elicited by previous SARS-CoV-2 infection and perhaps even by existing COVID-19 vaccines.
See more from MedicalBrief archives:
Prevalence of the double-jabbed in England’s first Omicron cases — UKHSA
Triple shot of Pfizer vaccination ‘neutralises Omicron variant ‘
So far, milder disease seen with Omicron, with shorter hospital stays — SA hospitals analysis