Could the coronavirus mutate if a vaccine can’t be found in time?Nachelle Geronimo
Could the coronavirus mutate if a vaccine can’t be found in time?
As scientists race to trace out paths the virus might take we ask the crucial questions.
An illustration of the 2019 novel coronavirus (2019-nCoV) provided by the Centers for Disease Control and Prevention. Photograph: AP
In just a month, the coronavirus outbreak has snowballed from a handful of cases to more than 40,000, reaching four continents and prompting an all-out battle to stop the spread across China and beyond. As those in Wuhan face shortages of hospital beds and supplies that have been likened to “wartime conditions”, experts and scientists are attempting to trace out the possible paths that the virus might take.
Can it be contained?
When Sars (severe acute respiratory syndrome) hit in 2002, after an initial surge in cases, the epidemic fizzled out. However, many experts believe the chances of this happening with 2019-nCoV are looking increasingly slim. In fact, the odds may have been more difficult even from the start of the latest outbreak, according to David Heymann, a professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine (LSHTM). “Sars emerged in one or two people,” he said. “This current outbreak it seems was quite explosive at the start – it was many different people infected at the start, and they each set off their own chain of transmission.”
Although the difference in initial case numbers may sound small – two people versus 16, say – in an epidemic where numbers of infections are doubling every five days that could have set back containment efforts by several weeks.
It is too early to calculate how effective quarantines have been in containing the spread. A slight levelling off in the number of global cases over the past few days has been taken by some as a cause for optimism, although this may also reflect difficulties in recording cases.
On Sunday, World Health Organisation chief Tedros Adhanom Ghebreyesus warned that cases of the coronavirus being transmitted by people who had never been to China could be “the tip of the iceberg”, while on Monday the UK health secretary, Matt Hancock, declared the virus “a serious and imminent threat to public health” after four new cases were diagnosed in the country.
“One has to be a little bit pessimistic at this stage,” said Prof Peter Smith, an epidemiologist at LSHTM. “There are a large number of cases in China, even though they’re putting in place these draconian measures to contain it. It’s looking increasingly likely that it will become well-established in China. The likelihood is then that it will leak to other countries.”
“My pessimistic view at this stage is that it is likely to become quite widespread and will be around for some time.”
If it’s not contained, will it be here to stay?
Some coronaviruses are seasonal and so it is possible that the number of cases may begin to dampen down as spring comes. But if the virus is already widespread by that point, it does not necessarily mean it is gone for good – just like flu, coronavirus could rear its head again next winter, at which point it would be considered an endemic human disease.
There are already four circulating coronaviruses (chances are you have had one – they cause about a quarter of common colds) that originally made the leap to humans from cows, bats and other animals.
“Coronaviruses have established themselves before. We have four of them that cause common cold-like illness,” said Amesh Adalja, an infectious disease specialist at the Johns Hopkins Center for Health Security. “There’s a very high chance that can be the fifth.”
If the coronavirus is still circulating in a year, its impact could be lessened by a level of immunity in the population and, possibly, the availability of vaccine to protect health workers and those most vulnerable. “This is the situation where a vaccine will become relevant,” said Smith.
Could the virus mutate?
Tests so far suggest that the coronavirus is relatively stable but as it is passed from human to human the virus will become more adapted as a human disease. This is not necessarily a bad thing, though. “In Darwinian terms, the virus wants to survive,” said Smith. “And to do that it’s generally not a sensible idea for a virus to kill people. The most successful viruses infect a lot of people and cause relatively little pathology.”
It’s worth noting that coronaviruses do not undergo the same type of genome shuffling that leads to the constantly shifting variety of flu strains in circulation. It is this genetic drift that means new flu vaccines have to be created each year and that means getting the flu once does not mean you’ll be immune next time it comes around. The coronavirus is not expected to mutate this rapidly and so once a vaccine is here, it should continue to work far into the future.
When will a vaccine be ready?
Teams around the world are racing to produce a vaccine, with some vaccine candidates already being tested in animals, just weeks after the coronavirus DNA sequence was released.
Jeff Richardson of Inovio Pharmaceuticals, one of the teams backed by funding from the Coalition for Epidemic Preparedness Innovations (Cepi), said the team’s DNA-based vaccine is already being manufactured on a larger scale for human testing projected to start early summer. A team from the University of Queensland, also backed by Cepi, is already testing its vaccine in combination with a technology developed by GSK, which makes the immune system respond more strongly to vaccines, potentially lowering the dose required by a factor of four.
Few people doubt that a viable vaccine will be in human testing by the summer. But these incremental trials, in which the numbers given the vaccine are ramped up from 20 to 200 and then thousands, will unavoidably take many months to ensure that the vaccine is safe and that even rare side-effects are spotted. A commercially available vaccine within a year would be quick.
Could we be better prepared for next time?
The global vaccines community faced severe criticism after the Ebola epidemic, which killed 11,000 people, over the failure to deploy a vaccine quickly enough; it took more than a year, despite a vaccine having been in development for a decade. This time things have moved more quickly. But some argue that there is still much more the world could do to prepare for infectious disease outside times of crisis.
Seth Berkley, head of the vaccine alliance Gavi, said: “The hardest thing for me is that we live in a world where we want to prevent. We have nuclear submarines as the third line of defence. We spend a lot of money to be prepared. But this is an evolutionary certainty whereas nuclear war is not – and yet we spend a lot less on this type of prevention.
“During the Ebola outbreak it was the Isis of infectious disease,” he added. “A few weeks after that people were like, ‘Ebola? Yesterday’s story.’ The question is, how do we get people to pay attention to this in peacetime?”
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