Live updates: follow the latest news on Covid-19 variant Omicron
A Pfizer drug has shown a very high level of effectiveness in preventing high risk, unvaccinated Covid-19 patients from needing hospital care, the company said on Tuesday.
Pfizer announced the results of two trials, the first of which looked at 673 adults at “standard risk” of Covid-19.
The pill did not reduce symptoms associated with breakthrough infections in this group, but the risk of hospital admittance was reduced by 70 per cent.
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In the second study, the drug was found to be 89 per cent effective at preventing hospital admittance among high risk, unvaccinated people. In this study, the pill was taken within three days of symptom onset. It was not clear whether the pill would have similar results if taken outside of this time window.
The second study confirmed Pfizer’s earlier analysis of results from a smaller number of patients. Taken together, the results suggest that use of the treatment could initially be restricted to patients at risk of developing severe disease.
But the mixed reading in healthier patients shows more study is likely to be needed before it becomes a go-to option for vaccinated individuals who develop frustrating but not life-threatening infections.
The high-risk finding “underscores the treatment candidate’s potential to save the lives of patients around the world”, Pfizer chief executive Albert Bourla said.
“If authorised or approved, this potential treatment could be a critical tool to help quell the pandemic,” he said.
In November, Pfizer signed an agreement with the UN-backed Medicines Patent Pool, an organisation that arranges supplies of vital drugs for developing countries at a lower cost.
Pfizer will waive royalty fees from selected manufacturers of the drug, which will make the pill cheaper in markets covered by the agreement. The agreement depends on the Covid-19 pandemic being classed by the World Health Organisation as a Public Health Emergency of International Concern.
Omicron Shield
Pfizer said tests indicated that the drug, Paxlovid, would be effective against the Omicron variant of the virus.
This was expected, as the medication is aimed at an internal protein, called a protease, that is not thought to mutate much between variants. Vaccines take aim at the spike protein, which is highly mutated in Omicron and could change in future variants.
If the results of the second trial are confirmed by regulators, emergency clearance and widespread use in high-risk patients could be granted as soon as Pfizer is able to produce the drug in sufficient quantities.
Pfizer senior vice president Annaliesa Anderson said the company started submitting data needed to gain a US emergency authorisation in high-risk patients “a while ago”, and that it would provide the new updated data to US regulators.
The results of the other study suggests a more complicated path for using the drugs in patients at lower risk of complications from the virus.
The standard-risk trial included vaccinated patients who had at least one risk factor for severe disease and low-risk unvaccinated people. Pfizer said an independent data monitoring committee had recommended that the trial continue.
Adverse events were similar between the drug and a placebo group in both trials, Pfizer said, suggesting there are no major side effect problems so far.
Important Target
In the standard-risk trial, the apparent decline in hospital admittances was not statistically significant owing to the small numbers of patients involved, said Ms Anderson, who heads Pfizer’s hospital unit, which includes antiviral research.
She said the company had focused on symptom reduction as the primary goal of the standard risk study, not the need for hospital admittance.
“We are working through what our path forward will be in this patient population,” Ms Anderson said.
