India’s Omicron tally rose to 53 on Tuesday with the National Capital recording four fresh cases of the COVID-19 Omicron variant. This, as China reported its first case of Omicron, Britain recorded its first death from the variant amid plans to launch a large booster programme, Norway tightened measures and Peru said it was battling a ‘resurgence’ of the pandemic.
The detection of the first Omicron cases two weeks ago coincided with soaring infection numbers across the world, and the variant added fuel to concerns about a global COVID resurgence. Dozens of nations have re-imposed border restrictions in response to the spread of the new virus variant and raised the possibility of a return of economically punishing lockdowns.
On Wednesday, WHO chief Tedros Adhanom Ghebreyesus summarized what is so far known about the variant: it poses higher infection risks to people who have already had the virus or been vaccinated than previous variants, and there is a preliminary indication it could cause milder disease. But even if confirmed to be less severe, the variant is likely even more transmissible than Delta, meaning it could reach and thus sicken more people.
Thus the question in everyone’s minds: Do vaccines work against Omicron? If so, what is their efficacy?
Let’s take a look at what experts and studies say:
40-fold drop in ability of antibodies to neutralise Omicron: RSA study
Preliminary results from a small study in South Africa suggested there was up to a 40-fold drop in the ability of the antibodies from the Pfizer-BioNTech vaccine to neutralise Omicron, compared to an early strain. The results suggest “that there is definitely much less neutralisation against Omicron compared to neutralisation against the original strains that came out of Wuhan initially,” said Willem Hanekom, executive director of the Africa Health Research Institute, which carried out the study.
But he cautioned that it was important to be “extraordinarily careful” interpreting the results because they only reflect a laboratory setting, while real-world data was the true test.
Antibody reductions were also seen in a German study and one carried out in Sweden, but they varied in precise magnitude. Omicron counts more than 30 mutations on the spike protein that dots the surface of the coronavirus and allows it to invade cells, and a high degree of immune evasion was widely anticipated.
But virologist Angela Rasmussen of Canada’s Vaccine and Infectious Disease Organization said she was encouraged by a finding in the South African research that showed the Omicron variant used the same “receptor” — known as ACE2 — to enter cells, as opposed to mutating in a more fundamental way.
Experts remain cautious
Experts remain cautious about the data from the study. “Too early to say but it confirms that hybrid immunity will be better protected,” Anurag Agrawal, chair, WHO’s technical advisory group on SARS-CoV-2 virus evolution, told Economic Times. “We need data with our peoples’ sera,” Agrawal added.
Samiran Panda of the Indian Council of Medical Research said it’s not correct to extrapolate the results for the vaccine not used in India. “The vaccine platform is different. We don’t know how our vaccines will work. So, there’s no point inferring anything from the new study,” he said.
Speaking to NDTV on Sunday , WHO Regional Director for South East Asia Dr Poonam Khetrapal said, “While studies are going on, in view of multiple mutations in Omicron, it is reasonable to assume that the current vaccines offer protection against severe diseases and death.”
Priority should be given to populations at higher risk, including adults, healthcare workers, and those with underlying conditions, she added
With Omicron cases being reported among those vaccinated too, Dr Khetrapal said, “It is important to know that while vaccines prevent your chance of being infected… they don’t completely block it. This is true for all variants.”
Oxford study: Two doses of vaccines generate lower level of antibodies
Two doses of Pfizer and AstraZeneca COVID-19 vaccines generate lower levels of antibodies against the Omicron variant of coronavirus, according to a study which suggests that those previously infected or vaccinated may be at an increased risk of infection. Researchers from the University of Oxford in the UK analysed the impact of the Omicron variant of concern on one of the immune responses generated by vaccination.
The yet-to-be peer-reviewed study, posted on the preprint repository MedRxiv on Monday, used blood samples from individuals who had previously received two doses of the AstraZeneca or Pfizer vaccines, and a live virus isolate. The researchers demonstrate substantial decrease in neutralising titres — a measure of the level of neutralising antibodies generated in responses to vaccination against, or infection from, COVID-19.
The results indicate that the Omicron variant has the potential to drive a further wave of infections, including among those already vaccinated, the researchers said. They, however, noted that there is currently no evidence of increased potential to cause severe disease, hospitalisations or deaths in vaccinated populations.
These results align with recently published data from UK Health Security Agency, showing reduced effectiveness of two doses of these vaccines against symptomatic disease due to the Omicron variant compared to Delta. This effectiveness was, however, improved by a third dose of vaccine, the researchers said.
“These data will help those developing vaccines, and vaccination strategies, to determine the routes to best protect their populations, and press home the message that those who are offered booster vaccination should take it,” said Professor Gavin Screaton, Head of the Oxford’s Medical Sciences Division, and lead author of the paper.
“Whilst there is no evidence for increased risk of severe disease, or death, from the virus amongst vaccinated populations, we must remain cautious, as greater case numbers will still place a considerable burden on healthcare systems,” Screaton said.
The researchers noted that these data are important but are only one part of the picture. They only look at neutralising antibodies after the second dose, but do not tell us about cellular immunity, and this will also be tested using stored samples once the assays are available, they said.
“Importantly, we have not yet assessed the impact of a ‘third dose’ booster, which we know significantly increases antibody concentrations, and it is likely that this will lead to improved potency against the Omicron variant,” said Matthew Snape, a professor at the University of Oxford and co-author of the study.
“Vaccination induces many arms of our immune system, including neutralising antibodies and T-cells,” said Teresa Lambe, a professor at the University of Oxford, and an author on the paper.
“Real-world effectiveness data has shown us that vaccines continue to protect against severe disease with previous variants of concern. The best way to protect us going forward in this pandemic is by getting vaccines in arms,” Lambe added.
Three doses ‘effective’ against Omicron: Pfizer/Biotech
Two doses of the BioNTech and Pfizer coronavirus vaccine may not be enough to protect against the Omicron strain, the companies warned Wednesday, but they stressed it was “still effective” after a third jab.
The companies’ news was called reassuring by experts, and came as the first independent data from labs around the world emerged, suggesting that the new variant is better at evading vaccine-trained immunity than those before it.
In preliminary results published on Wednesday, Pfizer and BioNTech said their vaccine “is still effective in preventing Covid-19, also against Omicron, if it has been administered three times”.
But they warned that “the Omicron variant is probably not sufficiently neutralised after two doses.”
According to early laboratory research using blood serum from vaccinated people, a booster third dose generated around the same level of antibodies against Omicron as is seen after a second dose with the initial strain.
Blood samples from around 20 people who had received two doses of the current vaccine showed on average a 25-fold reduction in neutralising antibodies compared to the early strain of the virus, the companies said.
But they added that another part of the immune response — from T cells — were probably still effective against the variant, adding that “vaccinated individuals may still be protected against severe forms of the disease”.
Their results have not been peer reviewed.
“We still need to be very measured and take a wait and see approach, but I think what we do have is at least encouraging,” virologist Rasmussen said.
“Boosters will definitely be helpful in keeping the rate of Omicron breakthrough slower,” she added.
Speaking at a press conference, BioNTech CEO Ugur Sahin said that reducing the time required between second and third doses of the vaccine was the “right way to go” to increase protection through the winter.
The vaccine-makers said that an Omicron-specific version of the jab, currently in development by BioNTech, would be ready for delivery by March, pending regulatory approval.
The decision to switch production to the tailored vaccine would depend on Omicron’s spread.
To sum it up? The verdict isn’t in yet.
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With inputs from agencies