A new coronavirus pandemic could strike in 2028, scientists have warned.
Prior to the ongoing pandemic, a global infectious outbreak had not occurred since 1918, when Spanish flu killed up to 50 million people.
More recent outbreaks like swine flu, Ebola and Zika did not evolve into pandemics, but may have had the potential to spread further afield.
When it comes to coronaviruses specifically, the infection behind the ongoing pandemic is one of seven strains of a virus class that are known to infect humans.
Other strains can cause Severe acute respiratory syndrome (Sars), which killed 774 people during its 2002/3 outbreak, with the last case being reported in 2004.
Another coronavirus strain can trigger Middle East respiratory syndrome (Mers), which killed 858 people when it emerged in 2012, with a handful of incidences still arising every year.
Based on the approximate seven-year pattern with which new coronavirus strains emerge, scientists from Northwestern University believe a new one could appear in 2028 – and have the potential to evolve into a pandemic.
The team is preparing for this, having identified a coronavirus drug target that should be effective against any new strains.
Governments around the world have been accused of being unprepared for the current pandemic.
Infectious outbreaks have always occurred. Many worry they will become more common, however, as urban sprawl infringes on natural environments, moving humans and animals closer together.
The government recently confirmed the launch of its Centre for Pandemic Preparedness, "which will spearhead [the] UK's work to develop a global early warning system to detect new infectious disease threats".
A new partnership between the UK and US also aims to fight these global outbreaks, by "bolstering disease surveillance, as well as genomic and variant sequencing capacity worldwide".
Many are also optimistic the coronavirus pandemic has made people more aware of the importance of regular hand washing, adequate ventilation and face coverings, when required.
Erring on the side of caution, the Northwestern scientists are preparing for another coronavirus pandemic. They have previously mapped the structure of a protein called nsp16, "which is present in all coronaviruses".
While only seven strains are known to infect humans, other coronaviruses are present in animals, with these having the potential to "jump" from one species to another. The virus behind the ongoing pandemic is believed to have started in bats, before "jumping" into humans, possibly via pangolins.
Nsp16 may help coronaviruses "hide from the immune system", with the pathogens using the protein "as the template for all the viral building blocks".
Writing in the journal Science Signalling, the scientists believe a drug that fits in nsp16's "pocket" may block the protein's function.
Targeting nsp16 early in a patient's infection may prevent them from becoming severely ill, particularly if a drug was taken as part of a cocktail of treatments.
While each coronavirus strain has distinct physical properties, "nsp16 is nearly the same across most of them", while its pocket "is present in all the different coronavirus members".
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Amid the ongoing pandemic, numerous drugs have been tested for their potential to ward off or treat severe disease, with studies throwing up mixed results.
Critically ill coronavirus patients are commonly given the arthritis drug tocilizumab and the steroid dexamethasone. Both of these target the individual's immune response, which can trigger damaging inflammation if it goes into overdrive.
Scientists from the University of Oxford recently revealed an experimental antibody treatment cuts the risk of death among "the sickest" patients by targeting the coronavirus itself. Critically ill individuals were previously thought to be too far along in their illness for virus-targeting drugs to have an effect.
Known as REGEN-COV, the Oxford drug is expensive, at up to £2,000 ($2,796) per patient. It was also only infused into hospitalised patients, not those with mild symptoms.
When asked about REGEN-COV's potential as a preventative drug, one of the Oxford scientists said it would not be "cost effective or practical to treat patients who might have done just fine anyway".
Nevertheless, a less expensive treatment – that could be taken at home – could ward off severe disease in future outbreaks, preventing deaths and pressure on healthcare systems.
"God forbid we need this, but we will be ready," said Professor Karla Satchell, lead author of the Northwestern study,
"There is great need for new approaches to drug discovery to combat the pandemic and infections from future coronaviruses.
"The idea is this future drug would work early in the infection.
"If somebody around you gets the coronavirus, you would run to the drugstore to get your medication and take it for three or four days.
"If you were sick, you wouldn't get as sick".
The drug could even ease common colds, which are triggered by four coronavirus strains.
The Northwestern scientists are said to be working with chemists to design treatments that work against nsp16.
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