Pfizer's Covid-19 vaccine provides less immunity to Omicron than to other strains: Early study

Omicron resulted in about a 40-fold reduction in levels of neutralising antibodies produced by people who had received two doses of the Pfizer-BioNTech SE shot, compared with the strain detected in China almost two years ago.
Pfizer's Covid-19 vaccine has been seen to be providing less immunity to Omicron than to other variants in an early study. (REUTERS / File Photo)
Pfizer's Covid-19 vaccine has been seen to be providing less immunity to Omicron than to other variants in an early study. (REUTERS / File Photo)
Published on Dec 08, 2021 06:37 AM IST
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Written by Joydeep Bose | Edited by Poulomi Ghosh, Hindustan Times, New Delhi

Researchers in South Africa have found in an early study that Pfizer's vaccine against the coronavirus disease (Covid-19) actually provides less immunity to the Omicron variant than to other major versions of the virus. In lab experiments conducted at the Africa Health Research Institute in Durban, it was observed that Omicron resulted in about a 40-fold reduction in levels of neutralising antibodies produced by people who had received two doses of the Pfizer-BioNTech SE shot, compared with the strain detected in China almost two years ago.

Also Read | Omicron versus Delta: Fauci breaks down what is known and what's unknown

Alex Sigal, the head of research at the laboratory, said that the loss of immune protection is “robust, but not complete” and that further efficacy studies are needed to appropriately take on board the exact extent of the vaccine's impact in mitigating the disease caused by this new strain.

Speaking at an online presentation of the first reported experiments gauging the efficacy of the Pfizer Covid-19 vaccine against Omicron, Sigal said there will be “more breakthrough” of vaccine-induced immunity as he pushed the idea of getting booster shots to protect oneself against the new variant.

“A good booster probably would decrease your chance of infection, especially severe infection leading to more severe disease,” the Bloomberg news agency quoted the researcher as saying. “People who haven’t had a booster should get one, and people who have been previously infected should be vaccinated.”

Although these are early studies into the efficacy of existing vaccines against Omicron, the preliminary results have raised concerns that immune protection from vaccination or a previous bout of Covid-19 may be insufficient to stop reinfections or stem a fresh wave of cases and hospitalisations.

Also Read | Omicron variant: What we know so far on cases in India and vaccine efficacy

A top WHO official, however, said on Tuesday that there is no reason to assume that Omicron is more severe than the variants which came before, or that existing vaccines will fail against it. Michael Ryan, the World Health Organisation's emergencies director, told AFP in an interview that there currently is no indication to suggest existing vaccines would fail to protect people who contract Omicron against the worst outcomes of the disease.

A similar assurance was echoed on Tuesday by US infectious diseases expert Anthony Fauci, who said that Omicron is certainly not worse than the previous strains, including Delta.

However, both the experts agreed that more epidemiological data from around the world is needed to affirm scientific consensus on this. Since South Africa announced the discovery of Omicron on November 25, about 450 researchers globally have been working to isolate the variant from patient specimens, grow it in labs, verify its genomic sequence, and establish methods to test it in blood plasma samples, according to WHO.

Sigal’s laboratory was the first to isolate the Beta variant, a strain of the coronavirus that was identified in South Africa late last year. The latest research in his lab involved testing 14 blood plasma samples collected from a dozen people who had been given a second Pfizer-BioNTech shot about a month earlier to gauge the concentration of antibodies needed to neutralise or block the virus.

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