Shoppers crowding onto city streets. Office workers squeezed into packed train carriages heading towards bustling towns. And holidaymakers rushing through the check-in gates, waving only their passports and visas at officials. 

Life, to many, seems reassuringly normal once again. After two years it would rather forget, the world is moving on from the Covid-19 pandemic.

But while people slip back into their old routines, new diseases continue to hit the headlines. MonkeypoxA viral disease causing a rash, fever and other symptoms. It was found mainly in central and western Africa before spreading more widely in 2022. has jumped from rodents to humans and Russian scientists have discovered Khosta-2A virus identified in horse-shoe bat samples in Russia in 2022. in bats. Now Europe is seeing its most lethal bout of avian fluAn infectious type of influenza that spreads mainly among birds.. 

Bird flu normally dies out over the summer months. This year is different. The UK is facing its largest ever outbreak of the disease and experts fear cases will only increase as migrating birds bring new viruses back to Britain this winter.

"The severity of the situation... is unprecedented and very, very scary," says Jeff Knott, the RSPBThe Royal Society for the Protection of Birds, founded in 1889, is Britain's largest conservation charity.'s  director of policy.

Human transmission is possible, if unlikely. Only one person in England caught bird flu last winter. But viruses mutate, adapting to human cells, so for now, scientists are still uncertain about the risk it poses to humans. Could avian flu, described as "out of control" in Europe, be the start of the next pandemic? 

In 2020, Covid-19 shocked the world. Many scientists say it should not have. A pandemic like Covid-19 was not all that improbable. Although most governments wrongly assumed that influenzaAlso known as the flu, a common viral infection among humans causing a high temperature. would be the cause of the next global outbreak, we knew from Asia's SARSSevere Acute Respiratory Syndrome, a disease that makes it very difficult to breathe. Between 2002 and 2003, an outbreak of Sars in Southern China caused 774 deaths in 37 countries. It had a 9.6% fatality rate, and spread from civet cats to humans. epidemic in 2003 that coronaviruses could spread easily too. 

In fact, the probability of a pandemic on the scale of Covid-19 is increasing by 2% annually. This is linked to societal patterns of deforestation, urbanisationThe increase in the proportion of people living in towns and cities. It is predicted that by 2050 three billion people will live in cities. and meat production, which bring animals closer to human environments, allowing more diseases to "jump" to humans.

In any given year, it is thought that the likelihood of such a major pandemic like Covid-19 is now around 3%, meaning a 47% to 57% chance of one happening in the next 25 years.¹

Some think humanity will be better prepared next time. Indeed, the success of East Asian countries like Taiwan in suppressing Covid-19 in 2020 was partly put down to a cultural hangover from SARS. Across the region, face masks and social distancing were already familiar concepts. 

In the UK, experts say 20,000 lives could have been saved by locking down one week sooner.² Both individual countries and global bodies have learned from their mistakes - the World Health Organisation established its Hub for Pandemic and Epidemic Intelligence in 2021. Covid-19 also forced us to speed up vaccine and testing technology, pushing forward our scientific understanding.

It is impossible to say for certain what the next pandemic will look like, when it will be or what disease will trigger it. Unlike Covid-19, avian flu is not a complete unknown.³ "But there is still so much we don't know about the virus," warns Knott. "We are in previously uncharted territory." 

For now, only one thing is clear: finding out the answers to these unknowns is one of scientists' top priorities. 

Yes: Before Covid-19, something like avian flu was seen as the most likely type of virus to cause a pandemic. A new pandemic on the scale of Covid is not just possible, it is probable.

No: Covid-19 has taught us the lessons that we needed to tackle the next pandemic, however it begins. We are unlikely to have another crisis on that scale again - and it is too soon to point the finger at bird flu. 

Or... We have undoubtedly learnt some lessons from Covid-19.  But ultimately, the scale of any pandemic-style event will depend on the nature of the pathogenA bacteria, virus, or any other tiny organism that can cause disease. and how infectious it becomes. We will not know this until it comes.