Some countries have already begun administering fourth doses of Pfizer. Photo / Getty Images
Some countries have already begun administering fourth doses of Pfizer. Photo / Getty Images
Pfizer's chief executive has revealed that two doses of the current Covid-19 vaccine offer "very limited protection, if any" against Omicron, although two doses plus a booster offer "reasonable protection" against hospitalisation and death.
Albert Bourla made the comments in an interview with Yahoo Finance after the company announced anew Omicron-specific version of the vaccine would be ready by March, with doses already being manufactured.
"We know that the two doses of the vaccine offer very limited protection, if any," Dr Bourla said.
"The three doses with a booster, they offer reasonable protection against hospitalisation and deaths – against deaths, I think, very good, and less protection against infection.
"Now we are working on a new version of our vaccine, the 1.1, let me put it that way, that will cover Omicron as well. Of course we are waiting to have the final results, [but] the vaccine will be ready in March."
Some countries have already begun administering fourth doses of Pfizer. Photo / Getty Images
In a separate interview with CNBC, Bourla said Pfizer's new vaccine would also target other variants currently circulating.
"The hope is that we will achieve something that will have way, way better protection particularly against infections," he said.
"Because the protection against the hospitalisations and the severe disease – it is reasonable right now, with the current vaccines as long as you having, let's say, the third dose."
He added that it also remains unclear whether a fourth shot will become necessary, with Pfizer set to conduct experiments on the issue.
Omicron, which first emerged in southern Africa in November, quickly swept the world, overtaking Delta to become the most dominant strain and casting concern over the efficacy of existing vaccines.
The Pfizer and Moderna vaccines – both of which have been distributed in Australia – are only about 10 per cent effective at preventing symptomatic infection from Omicron 20 weeks after the second dose, a study from the UK Health Security Agency found.
While two doses still provide good protection against severe illness, the study found that booster shots increased protection against symptomatic infection to 75 per cent.
Pfizer claims its own studies show a third dose of its vaccine produces a 25-fold increase in neutralising antibodies against the new strain.
Early in 2021, Bourla had said data showed Pfizer's vaccine "was 100 per cent effective against severe Covid-19".
Excited to share that updated analysis from our Phase 3 study with BioNTech also showed that our COVID-19 vaccine was 100% effective in preventing #COVID19 cases in South Africa. 100%! https://t.co/E2ksTJSopU
The announcement of an updated vaccine comes as a number of states in Australia mandate booster doses of the existing versions for some industries such as healthcare.
But some experts have questioned the justification for mandates of a vaccine that evidence shows is no longer stopping transmission.
Writing in The Wall Street Journal on Sunday, Nobel prize-winning virologist Luc Montagnier and constitutional scholar Jed Rubenfeld argued the rise of Omicron had made the Biden administration's vaccine mandates "obsolete".
"It would be irrational, legally indefensible and contrary to the public interest for government to mandate vaccines absent any evidence that the vaccines are effective in stopping the spread of the pathogen they target," they wrote.
They pointed to the World Health Organisation's (WHO) position on vaccine mandates, which states that "if mandatory vaccination is considered necessary to interrupt transmission chains and prevent harm to others, there should be sufficient evidence that the vaccine is efficacious in preventing serious infection and/or transmission".
For Omicron, they noted, "there is as yet no such evidence" and moreover, "the little data we have suggests the opposite".
"One preprint study found that after 30 days the Moderna and Pfizer vaccines no longer had any statistically significant positive effect against Omicron infection, and after 90 days, their effect went negative – ie vaccinated people were more susceptible to Omicron infection," they wrote.
"Confirming this negative efficacy finding, data from Denmark and the Canadian province of Ontario indicate that vaccinated people have higher rates of Omicron infection than unvaccinated people."
Montagnier and Rubenfeld added that while there was "some early evidence" that boosters may reduce Omicron infections, "the effect appears to wane quickly, and we don't know if repeated boosters would be an effective response to the surge of Omicron".
Their comments come after the UK's head vaccine adviser, Professor Sir Andrew Pollard, who helped develop the Oxford-AstraZeneca vaccine, called for an end to ongoing mass vaccination.
Pfizer CEO Albert Bourla. Photo / Getty Images
"It really is not affordable, sustainable or probably even needed to vaccinate everyone on the planet every four to six months," Prof Pollard told BBC Radio 4's Today program. "In the future, we need to target the vulnerable."
On Monday, WHO called on vaccine makers to review the "strain composition" of the current vaccines in the face of Omicron.
"The Technical Advisory Group on Covid-19 Vaccine Composition considers that Covid-19 vaccines that have high impact on prevention of infection and transmission, in addition to the prevention of severe disease and death, are needed and should be developed," WHO said in a statement.
"Until such vaccines are available, and as the SARS-CoV-2 virus evolves, the composition of current Covid-19 vaccines may need to be updated, to ensure that Covid-19 vaccines continue to provide WHO-recommended levels of protection against infection and disease by variants of concern, including Omicron and future variants."
