Pfizer is hailing its experimental drug for treating COVID as a “gamechanger” after it was found to cut rates of hospitalisation or death by nearly 90 per cent in vulnerable patients.

The drug company is so confident it has stopped trials early and is pursuing approvals while governments are also getting their orders in quick, with the USA securing millions of doses.

The results appear to surpass those seen with Merck & Co’s pill molnupiravir, which was shown last month to halve the likelihood of dying or being hospitalised for COVID-19 patients also at high risk of serious illness.

Full trial data is not yet available from either company.

US President Joe Biden said Pfizer’s pill would be “another tool in our toolbox to protect people from the worst outcomes of COVID.”

“If authorised by the FDA we may soon have pills that treat the virus in those who become infected,” Mr Biden said.

Vaccines are regarded as the best way to control the pandemic but researchers are also seeking out effective treatments to reduce illness in infected people.

Pfizer hopes its drug can eventually be given to treat people at home, with three pills given twice daily, before patients get sick enough to go to the hospital.

The medication, which will have the brand name Paxlovid, is given in combination with an older antiviral called ritonavir.

Pfizer said it plans to submit interim trial to the US Food and Drug Administration as part of the emergency use application it opened in October.

The company is in discussions with 90 countries over supply contracts for its pill, said CEO Albert Bourla.

Pfizer’s study involved 1219 patients with mild to moderate COVID-19 and at least one risk factor for developing severe disease, such as obesity or older age.

It found that 0.8 per cent of those given Pfizer’s drug within three days of symptom onset were hospitalised and none had died by 28 days after treatment.

That compared with a hospitalisation rate of seven per cent for placebo patients. There were also seven deaths in the placebo group.

Rates were similar for patients treated within five days of symptoms.

Antivirals need to be given as early as possible, before an infection takes hold, in order to be most effective. Merck tested its drug within five days of symptom onset.

Pfizer’s drug, part of a class known as protease inhibitors, is designed to block an enzyme the coronavirus needs in order to multiply.

Pfizer is also studying whether its pill could be used by people without risk factors for serious COVID-19 as well as to prevent coronavirus infection in people exposed to the virus.

Gene linked to higher COVID risk

British scientists have identified a version of a gene more common in people of South Asian ancestry that may be associated with double the risk of lung failure from COVID-19.

The finding provides new insights into why some people are more susceptible than others to severe illness and opens possibilities for targeted medicine.

The high-risk genetic variant is in a chromosome region that is also tied to double the risk of death in COVID-19 patients under age 60.

About 60 per cent of people with South Asian ancestry carry the high-risk version of the gene, said researchers at Oxford University.

They said the discovery may partly explain the high number of deaths seen in some British communities and the devastation wrought by COVID-19 in the Indian subcontinent.

The study “shows that the way in which the lung responds to the infection is critical,” said Professor James Davies.

“This is important because most treatments have focused on changing the way in which the immune system reacts to the virus.”

The scientists found the increased risk comes from a gene that regulates activity of other genes, including one called LZTFL1 involved in the response of lung cells to viruses.

As a result, the gene variant could inhibit proper response to the virus among cells lining airways and the lungs.

However, LZTFL1 does not affect the immune system that makes antibodies to fight off infections, researchers said, adding that people carrying the variant should respond normally to vaccines.

Dr Raghib Ali of the University of Cambridge, an adviser on COVID-19 and ethnicity to the UK Cabinet Office, said in a statement that even after accounting for higher rates of COVID-19 risk factors such as work in public-facing jobs and housing in densely populated areas, “there has been an unexplained residual excess risk in South Asians”.

This new study, he added, shows “that this may be due to them being more likely to carry this gene which increases their risk of death once infected”.

The findings were published in the Nature Genetics journal.

Dr Simon Biddie, an intensive care specialist at the University of Edinburgh, said in a statement that while the study “provides compelling evidence to suggest roles for LZFTL1” in the lungs of patients with severe COVID-19, more research is necessary to confirm the findings.

-with AAP