Future pandemics could be even more lethal than Covid-19 so the lessons learned from the outbreak must not be squandered and the world should ensure it is prepared for the next viral onslaught, one of the creators of the Oxford-AstraZeneca vaccine said.

The novel coronavirus has killed 5.26 million people across the world, according to Johns Hopkins University, wiped out trillions of dollars in economic output and turned life upside down for billions of people.

"The truth is, the next one could be worse. It could be more contagious, or more lethal, or both," Sarah Gilbert said in the Richard Dimbleby Lecture, the BBC reported. "This will not be the last time a virus threatens our lives and our livelihoods."

Gilbert, a professor of vaccinology at the University of Oxford, said the world should make sure it is better prepared for the next virus.

"The advances we have made, and the knowledge we have gained, must not be lost," she said.

Efforts to end the Covid-19 pandemic have been uneven and fragmented, marked by limited access to vaccines in low-income countries while the "healthy and wealthy" in rich countries get boosters, health experts say.

A panel of health experts set up by the World Health Organisation to review the handling of the SARS-CoV-2 pandemic has called for permanent funding and for greater ability to investigate pandemics through a new treaty.

One proposal was for new financing of at least $10 billion a year for pandemic preparedness.

The Covid-19 outbreak was first detected in China in late 2019. Vaccines were developed against the virus in record time.

Gilbert said the Omicron variant's spike protein contained mutations known to increase the transmissibility of the virus.

"There are additional changes that may mean antibodies induced by the vaccines, or by infection with other variants, may be less effective at preventing infection with Omicron," Gilbert said.

"Until we know more, we should be cautious, and take steps to slow down the spread of this new variant."