They say music brings people together, but in the case of a pair of young researchers in Canberra in the 1970s, a mutual love of opera may have set a Nobel prize-winning partnership in motion.
It was 1973, and Rolf Zinkernagel, then only a few years out of medical school and a keen opera fan, left his Swiss home to join a research group at the Australian National University.
He was given a spot in a laboratory with Peter Doherty, a postdoctoral researcher at the time.
"It was a very small lab, so they put him in with me probably because I was the only other guy there who appreciated classical music," chuckles Professor Doherty, half a century later, sitting in a meeting room in the Melbourne medical research institute that bears his name.
Their shared interests didn't end at the operatic arts. The young scientists were also eager to untangle the intricacies of the immune system.
During their studies, they revealed how our immune system recognises cells in our body that have been infected by a virus — revelations that would snare them the Nobel Prize in Physiology or Medicine in 1996.
They had arranged to celebrate the 25-year anniversary of the occasion in 2021, but in a somewhat ironic twist, a viral disease — COVID-19 — put a pin in those plans.
So during their belated commemoration, Professors Doherty and Zinkernagel, now 82 and 78 years old respectively, sat down with ABC Science to chat about the pandemic, what lies ahead — and how the infamous "Dan Murphy opening hours" tweet changed Professor Doherty's drinking habits.
Will we ever see the last of COVID-19?
Like many experts in pandemics and infectious diseases, Professor Doherty suspects COVID-19 is here to stay.
"The best expectation is it will become a very mild infection, which I think will be around in the long term, and we will have it regularly and barely notice.
"But it's not at that level yet. It still can make people quite sick."
His biggest worry, though, is long COVID — when people continue having symptoms such as heart palpitations and extreme fatigue weeks and months after being infected with the SARS-CoV-2 virus.
In Australia, modelling predicts up to 500,000 people could have long COVID this year, with 20 per cent of those experiencing "significant impacts".
"And they're not necessarily getting really good clinical care, because the money is not there for it," Professor Doherty says.
"With these latest Omicron subvariants, we're all hoping [rates of long COVID] will be much lower, but we don't know that for sure yet.
"What we've been struggling with all along is the fact that this is a constantly evolving and changing situation, and evolving and changing in ways that we didn't really expect."
What can we take from this pandemic into the next?
For Professor Zinkernagel, the rapid development of COVID vaccines using the relatively new mRNA technology was "remarkable, and a sign of success for science and research".
"I think it's extraordinary that within a few months, we had a vaccine.
"Whether the vaccine does a very good job or just a good job [with the new subvariants] is another question, but the principle has been proved effective."
While vaccines have undoubtedly helped turn the tide against COVID-19 in parts of the world where they were widely distributed, we now know they're simply not enough on their own, Professor Doherty says.
For that reason, we must have antiviral treatments developed, tested and ready for the next pandemic.
"There are a limited number of types of viruses that are likely to cross over [from animals] and cause pandemics," Professor Doherty says.
"So you could make an antiviral drug that will work against all the henipaviruses [which can cause Hendra virus disease], or the arenaviruses [which can jump between rodents and humans], as these different classes of viruses could potentially cause a pandemic.
"I hope we've learnt this lesson: we can't rely totally on vaccines."
And conditions are ripening for another pandemic.
As we've seen with COVID-19, speedy international travel means diseases can spread faster and more freely than ever before.
The world's population, which ticked over to 8 billion a month ago, continues to rise, and more than half of us live in urban areas — a figure tipped to rise to 80 per cent by 2050.
"When you look at the situation in the 14th century, when smallpox came into Europe, more than 50 per cent of the city population died," Professor Zinkernagel says.
"But there were many areas where nobody died of smallpox, because the population density was too low for productive transmission."
How did you belatedly celebrate the Nobel anniversary?
It was a low-key affair: the pair say they're well past hitting the town to celebrate.
And since his infamous and accidental "Dan Murphy opening hours" tweet during the first lockdown of the pandemic, Professor Doherty has given up drinking alcohol.
"And we need to be in bed by 9:30pm," he laughs.
"Basically, it's 26 years since the Nobel Prize, but next year it's 50 years since we made that [Nobel-winning] discovery, so that's taken its toll in years.
"But Rolf's still off climbing mountains and I'm still ambulant, and we're both functioning intellectually at some reasonable level, so we're OK."
