The Omicron variant of COVID-19 “exceeds” all other strains in its potential ability to evade the antibodies produced by previous infection or vaccination, according to early research.
However, the study, published in the journal Emerging Microbes & Infection, found that people with this level of immunity may possess “stronger than basic” defence against the mutated virus. While a third dose of one of the vaccines may bolster this immunity, the team said more research is required to determine the extent to which this measure would prove effective.
Omicron can evade immunity
The study, one of the first peer-reviewed efforts to take on the new variant, confirms early reports out of South Africa — where it was first detected — that Omicron was able to easily evade immunity, according to Youchun Wang, lead author and senior research fellow from the National Institutes for Food and Drug Control in China. “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,” he said.
“However, the average ED50 (protection level) against Omicron is still higher than the baseline, which indicated there is still some protection effect can be observed.”
But because the antibodies providing this protection — whether gained from previous infection or vaccination — begin to wane over a six month period, Wang cautioned the new variant may be “even better” at evading immunity.
The team arrived at its concerning conclusions by comparing in-vitro Omicron samples to 28 serum samples from patients recovering from the original strain of SARS-CoV2. They also analyzed four strains the World Health Organization considers to be “of concern” — such as the Delta variant — and two “of interest.” Further research in real-world settings is now required to better understand Omicron’s ability to evade antibodies.
“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 said.
Real-world vaccine effectiveness
One big caveat accompanying the study is that the research was conducted in-vitro (or outside a living organism) using pseudotyped (or manufactured) viruses. Researchers point out, however, that previous study conducted in the same manner has found in-vitro analysis to be a measure of “good correlation” and current vaccine literature has established “that the in-vitro neutralization assays are good predictors of vaccine protection efficacy and real-world vaccine effectiveness.”
In light of this, the team suspects their data “may well predict the potential reduction of vaccine protection against the new Omicron variant.”
“It needs to be re-evaluated whether the antibodies can still be effective against the Omicron variant,” they conclude. “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 COVID-19 pandemic.”
Although the new variant appears to be much more transmissible, scientists in South Africa said on Friday they have seen no signs that it causes more severe illness than the other strains. “Preliminary data does suggest that while there is increasing rate of hospitalization… it looks like it is purely because of the numbers rather than as a result of any severity of the variant itself, this Omicron,” said Joe Phaahla, the country’s health minister.
Dave Yasvinski is a writer with Healthing.ca
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