Johnson & Johnson's (J&J) Covid-19 vaccine has been proved to provide virtually no antibody protection against Omicron, the new variant, but for a small defence via stimulation of immune cells, Bloomberg reported citing recent laboratory experiment inferences.
The findings reiterate that the new strain can bypass human body's initial defences while many vaccines lose partial potency against Omicron, suggested by other studies.
Professor Penny Moore, a virologist from Johannesburg's University of The Witwatersrand, who presented the fresh findings, said that the experiments were conducted on blood plasma samples of people who had both doses of the Pfizer Inc-BioNTech SE vaccine and those jabbed with J&J single-shot vaccine.
The unit of antibody levels, geometric mean titers, fell from 1,419 units against the original coronavirus strain to 80 against Omicron among people shot with Pfizer.
Meanwhile, for those who received J&J, the units fell from a mere 303 for the original strain to undetectable levels against Omicron, Moore presented in an online session on Tuesday.
She said that Omicron indeed exhibited substantial escape from antibodies, but against the J&J vaccine, the situation was more alarming.
But Moore asserted that the human body has other protections against the virus.
However, J&J responded that the company is monitoring people's samples who were jabbed with their vaccine for neutralising activity against Omicron, while they are also working on a variant-specific vaccine. The company is confident in the robust humoral, and cell-mediated immune responses elicited by its vaccine, J&J's Janssen pharma unit said in a statement.
Thousands of South African health workers were subjected to the J&J vaccine study. The vaccine appeared to be preventing severe disease, and according to reports, no one had died among the subjects after getting infected by Omicron.
Discovery Health Ltd., South Africa's largest medical insurance provider, testified that two shots of Pfizer appeared to offer 70% protection against hospitalisation post the Omicron infection. Vaccines of Pfizer and J&J are the currently used shots in South Africa.