While it is known that Covid infections give natural antibodies, a new study has shown that people who are unvaccinated but were previously infected by the Delta Covid variant may have very little protection against the new vaccine-evading Omicron.
To measure antibody levels, researchers from the Medical University of Innsbruck, in Austria, compared the blood of those who had beaten Delta against Omicron, Daily Mail reported.
Only one out of seven samples produced enough of the infection-fighting proteins to neutralise Omicron.
"This essentially means the antibodies did not recognise Omicron as a threat due to its heavily mutated nature compared to the Delta variant," the researchers said.
On the contrary, Covid survivors who were also fully vaccinated showed an increased ability to combat the strain, suggesting that prior infection alone offers virtually no protection against catching Omicron, the report said.
The team also tested two doses of the Pfizer jabbed with Omicron and found that it fared better - nine out of 20 samples produced enough antibodies to fight off the new Covid variant before it caused infection.
A similar test for two doses of the Moderna jab showed only one out of 10 was successful in generating antibodies against Omicron, the report said.
Overall, the best results were found in five samples taken from those who had both survived a previous Covid infection and then later got a vaccine - a group of people the researchers dubbed the 'super-immune', the report said.
Although the study has small numbers, it added to research demonstrating Omicron's ability to dodge immunity, Professor Lawrence Young, a microbiologist from the University of Warwick in the UK was quoted as saying.
He stated it was "dangerous" to infer any findings from the study, and added that the study reinforced the importance of getting a booster.
"It's dangerous to extrapolate what this data means for immune protection in vaccinated individuals other than reinforcing the value of booster vaccination - which is likely to be similar to the super immune individuals in this study," Young noted.