Allowing coronavirus to circulate to achieve herd immunity 'could make it more deadly', experts warn
ALLOWING coronavirus to spread in an attempt to achieve herd immunity could make it more deadly, experts have warned.
Researchers claim that by not controlling outbreaks of viruses – like Covid – can give them chance to develop into more dangerous strains.
⚠️ Read our coronavirus live blog for the latest news & updates
The Exeter University team believe their findings contradict "conventional wisdom" that most new diseases evolve to eventually become harmless.
As Covid-19 has developed, different strains have emerged – with some being able to spread up to five times faster than previous strains.
A new strain detected in South Australia earlier this week is believed to have a "very short incubation period" and is so contagious people could be infected less than 24 hours after being exposed.
While in September, researchers suggested that a dominant strain of Covid could be adapting to get around barriers such as masks and hand-washing due to mutations in the spike proteins.
Just last month it was revealed that one mutation had fuelled the spread of the virus across Europe, spreading to the UK as tourists returned from Spain.
The 20A.EU1 strain was first detected in June in farm workers in Catalonia and Aragon and scientists claimed that it now accounts for half of the infections in the UK.
Exeter University researchers wanted to understand more about the evolutionary trade off between virulence and transmission of pathogens emerging in a new host species.
They exposed 50 variants of an infectious bacterial pathogen, known as Mycoplasma gallisepticum, on house finches that have never encountered the disease.
Their results showed that natural selection favours pathogens that inflict intermediate levels of harm, or virulence, on their host.
Dr Camille Bonneaud, of the Centre for Ecology and Conservation at the University of Exeter's Penryn Campus in Cornwall, who led the study, said: "We found that variants that were more virulent transmitted faster, but that variants of intermediate virulence were the most evolutionarily successful."
The researchers said that contrary to commonly held beliefs, variants of the pathogen that replicated faster during infection and achieved higher densities did not transmit better or faster than those that achieved lower densities.
Dr Bonneaud said: "This tells us that transmission is not always a numbers game and that we cannot use pathogen numbers as a proxy for their success."
Pathogens have one evolutionary goal – to reproduce – which is achieved through transmission, and the harm they cause to their host is incidental.
The experts suggest that if the pathogen meets resistance – such as a vaccinated person, someone who has recovered and is immune or social distancing measures, then the highly severe forms won't succeed as well.
This is when natural selection would favour the milder strains, so the disease can continue to reproduce, they say.
But they warn that the more people and environments the virus is exposed to, the stronger and more resistant they could become.
Both humans and animals are able to develop resistances to harmful pathogens over time – and if enough people develop it then it is classed as herd immunity.
It's why a coronavirus vaccine is so important – as the more people who are immunised, the less chance people have of spreading the virus and strains developing.
Today it was revealed that the UK is "weeks away" from distributing vaccines.
Offerings from Moderna and Pfizer are both currently in the works.
Meanwhile, Health Secretary Matt Hancock confirmed volunteers are currently being trained but the "big numbers" in terms of vaccinating people will be in the new year.
He told Today: "We've changed the law to change the number of clinically qualified people who can vaccinate because this is going to be one of the biggest civilian projects in history."
Firefighters will join a specially trained army of 40,000 extra workers recruited to roll out Pfizer jabs at record speed — with up to one million a day forecast.
NHS bosses will target retired doctors and nurses to help, as well as other workers with first-aid skills, such as firefighters, PCSOs and members of the Armed Forces.
Trainee medics and nurses, as well as other frontline health workers, will also be called upon under the radical new drive to beat the virus.
All will receive specialist training before delivering the Pfizer vaccine to Brits — supported by an additional 30,000-strong army of St John Ambulance volunteers.
Every major city will get a dedicated mass vaccination centre, with 50 initially planned in Nightingale hospitals, sports arenas and town halls.
A further 1,000 smaller Covid immunisation sites will be dotted across England.
NHS bosses want every GP practice to be able to deliver the coronavirus vaccine to patients in the long-term, according to details leaked to the Health Service Journal.
Source: Read Full Article