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Don’t panic: New COVID strains are not ‘escape mutants’ and vaccines should still work


Doug Hendrie


25/01/2021 4:23:38 PM

The variants have shut down nations and led to surges of new cases and deaths – but experts say current vaccines should still protect against the mutations.

Coronavirus mutation
New COVID variants are increasing, but experts say there is no need to panic yet.

Both the Brazilian and South African variants have a change that can reduce antibody binding, potentially reducing the efficacy of vaccines, as well as making a reinfection more likely. This polymorphism – e484k – is not present in the UK variant.
 
The Brazilian variant has triggered a disastrous new tide of infection in the city of Manaus in the Amazon, where fully 75% of the population contracted the virus last year.
 
This, experts fear, could point to a partial ‘immune escape’ – or suggest people who got milder cases in the first wave are faring worse with this new variant.
 
Preliminary data may indicate the UK COVID variant could be more deadly, as well as better able to spread, though scientists say this is not conclusive.
 
The recent emergence of many new COVID variants has led some UK experts to dub this a ‘new pandemic’.
 
But Australian experts have cautioned against panic about vaccine effectiveness against new strains of the coronavirus, given the heavy lifting of creating a novel vaccine from scratch was done last year.
 
If and when the virus is able to mutate to avoid the immune response triggered by vaccines, the experts say we would be able to pivot quickly to produce seasonal vaccines, just as we do for the faster-mutating influenza virus.
 
Still, the speed with which the variants are emerging is concerning, as vaccinologist Philip Krause, who heads a World Health Organization COVID-19 vaccine group, told Science
 
‘[T]he rapid evolution of these variants suggests that if it is possible for the virus to evolve into a vaccine-resistant phenotype, this may happen sooner than we like,’ he said.
 
Infectious disease physician Associate Professor Paul Griffin, who has run clinical trials for two COVID vaccine candidates, told newsGP that vaccine manufacturers are monitoring variant data in real-time to assess any impact on their vaccines.
 
‘We haven’t seen a true escape mutant yet, where the vaccines are ineffective. It is likely, though, and will become more likely as vaccines become more widespread. It’s more a question of when rather than if,’ he told newsGP.
 
‘This one is evolving relatively slowly … but it was only a matter of time before we saw strains that were more fit, more infectious or had other advantages.’
 
But Associate Professor Griffin stressed that the majority of vaccines will be able to move quickly to alter the target on the virus.
 
‘We won’t need to start over. It should be a small number of weeks to address a true escape mutant,’ he said.
 
Kirby Institute virologist Associate Professor Stuart Turville told newsGP the new variants have ‘taken the edge off’ vaccine effectiveness in some cases, but that none seem able to completely evade the immune response. He said the UK figures on higher lethality come from a very small data set.
 
‘To date, we have yet to see a single virus mutant with complete immune evasion that would make a vaccine useless,’ he said.
 
‘Many articles are yet to be peer-reviewed, but many point to the vaccines having enough breadth to deal with all of the virus variants.
 
‘Fortunately, the vaccine responses so far have been strong in many studies and this level of strength will hopefully translate to cover many different viral [strains].’
 
Associate Professor Turville said the Brazilian situation – with a seemingly high rate of reinfection – could be linked to people who had a mild case of the virus during the first wave seeing their immunity wane quickly, though he stressed the data was not conclusive. 
 
‘When we track the convalescent response for mild cases, their immune response is not very strong. They might only have a couple of months [of protection],’ he said.
 
By contrast, the immune response from those hospitalised by the virus lasts around eight months, according to Associate Professor Thurville.
 
The virus has already undergone at least one widespread adaptation to boost transmissibility in its new human hosts; the D614G mutation, which appeared last April. As 2020 wore on, this variant became the norm, outcompeting the original strain.
 
‘There are thousands of variants with really low prevalence. That’s microevolution doing its thing, and what’s coming up are those that are the fittest and those which may evade the immune system,’ Associate Professor Thurville said.
 
‘But it had been evolving slowly, with one or two changes a month. In a virus with a genome of 30,000 building blocks, that’s not a lot.’  
 
In recent months, however, the mutation rate has appeared to accelerate.
 
‘The more recent ones are a little more concerning,’ Associate Professor Thurville said.
 
‘We’ve gone from one or two changes a month to seeing eight on the spike protein in the UK variant. How is it doing that? How did it accelerate that change?
 
‘We’re still getting our heads around what it’s up to. It’s probably just becoming fitter, though we still don’t know if it’s immunoevasive.’
 
Associate Professor Thurville said the UK is shaping up as a unique testbed for vaccines, where a rapid vaccination effort is colliding with high prevalence of the virus, as well as new variants. 
 
But he predicted there would also be as-yet undescribed variants circulating in the US, which has the world’s most widespread COVID epidemic and the highest number of deaths.  
 
‘The US doesn’t have a system to track viruses like the UK does with its genome sequencing. So we’re yet to meet the American variants because no one has sequenced them yet,’ Associate Professor Thurville said.
 
If they prove necessary, seasonal COVID vaccines could be available much faster than this first generation of vaccines, according to Guardian science editor Ian Semple.
 
‘It is highly unlikely [regulators] will require [seasonal] vaccines to go through a whole new round of clinical trials, just as seasonal flu shots are approved without such trials,’ he wrote.
 
‘Though faster than updating flu vaccine, which is still grown in eggs, the whole process would still take months.’

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