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TWO strains of the killer coronavirus are spreading around the world

The coronavirus has mutated into at least two separate strains since the outbreak began in December, according to Chinese scientists.

Researchers say there are now two types of the same coronavirus infecting people – and most people seem to have caught the most aggressive form of it.

At least 94,000 people have been infected around the world and almost 3,200 have died, while 50,000 have recovered from the disease.

The team of experts from Beijing and Shanghai said 70 per cent of people have caught the most aggressive strain of the virus but that this causes such bad illness that it has struggled to spread since early January.

a man and a woman standing in front of a blue wall: Scientists in Beijing and Shanghai said 'human intervention measures' may have forced the most aggressive strain of the coronavirus into submission (Pictured: Medical workers at the Botkin Infectious Diseases Hospital in St. Petersburg, Russia)

© Provided by Daily Mail Scientists in Beijing and Shanghai said ‘human intervention measures’ may have forced the most aggressive strain of the coronavirus into submission (Pictured: Medical workers at the Botkin Infectious Diseases Hospital in St. Petersburg, Russia)Now an older, milder strain seems to be becoming more common.

Knowing that the virus can mutate may make it harder to keep track of or to treat, and raises the prospect that recovered patients could become reinfected.

The experts cautioned that the study that discovered the mutation only used a tiny amount of data – 103 samples – so more research is needed. 

a black and red text: More than 93,000 people have caught the coronavirus worldwide and at least 3,204 have died, according to today's figures

© Provided by Daily Mail More than 93,000 people have caught the coronavirus worldwide and at least 3,204 have died, according to today’s figures

The research was done by experts at Peking University in Beijing, Shanghai University and the Chinese Academy of Sciences.

In their study of genes in 103 samples of the coronavirus, which is named SARS-CoV-2 and causes a disease called COVID-19, they revealed they had discovered two distinct versions of it, which they named L and S.

They claimed that around 70 per cent of patients have caught the L strain, which is more aggressive and faster-spreading than S.

But L has become less common as the outbreak has gone on, with it apparently struggling to spread since early January, while S has become more common.

Slide 1 of 50: Army soldiers wearing protective suits spray disinfectant as a precaution against the new coronavirus at a shopping street in Seoul, South Korea, Wednesday, March 4, 2020. The coronavirus epidemic shifted increasingly westward toward the Middle East, Europe and the United States on Tuesday, with governments taking emergency steps to ease shortages of masks and other supplies for front-line doctors and nurses.Next SlideFull Screen1/50 SLIDES © Ahn Young-joon/AP Photo Army soldiers wearing protective suits spray disinfectant as a precaution against the new coronavirus at a shopping street in Seoul, South Korea, on March 4.

S is less aggressive but is thought to be the first strain of the virus which made the jump into humans and is continuing to infect new patients.

This could be because the disease it causes is less severe, meaning people carry it for longer before ending up in hospital, increasing the risk of them passing it on.

a group of people standing in front of a building: Human interventions like isolating and disinfecting areas where the virus was spreading fast may have largely stopped the most aggressive form of the virus (Pictured: South Korean military personnel disinfect streets in the city of Gyengan-dong)

I© Provided by Daily Mail Human interventions like isolating and disinfecting areas where the virus was spreading fast may have largely stopped the most aggressive form of the virus (Pictured: South Korean military personnel disinfect streets in the city of Gyengan-dong)n the paper the researchers, led by Professor Jian Lu and Dr Jie Cui, said: ‘Whereas the L type was more prevalent in the early stages of the outbreak

in Wuhan, the frequency of the L type decreased after early January 2020.

‘Human intervention may have placed more severe selective pressure on the L type, which might be more aggressive and spread more quickly.

‘On the other hand, the S type, which is evolutionarily older and less aggressive, might have increased in relative frequency due to relatively weaker selective pressure.’

The scientists’ explanation suggests that, because the L strain surged at the beginning of the outbreak and made people so ill, those who caught it were quickly diagnosed and isolated, meaning it had less opportunity to spread widely.

This ‘human intervention’ is thought to be the hospitalisation of people with the virus and the lockdown of areas where it was spreading fast.

a close up of a decorated cake: Coronaviruses are so named because their structure has jagged edges which look like a royal crown – corona is crown in Latin (Pictured, an illustration of the 2019-nCoV released by the US Centers for Disease Control and Prevention)

© Provided by Daily Mail Coronaviruses are so named because their structure has jagged edges which look like a royal crown – corona is crown in Latin (Pictured, an illustration of the 2019-nCoV released by the US Centers for Disease Control and Prevention)

If people with a certain strain of the virus are taken into hospital faster than those with another strain, this limits the number of other people that strain can infect.

A virus must make people ill enough that they spread it through coughing or sneezing, for example, but not so ill that they quickly become bed-bound or die, which would keep them away from other potential victims.

If the virus is prevented from infecting a lot of people, that strain may die off and evolution – via survival of the fittest – will allow another strain which can infect more people to become the dominant one.

The S strain may be winning because it causes milder symptoms so patients take longer to realise they’re sick, increasing the risk of them passing it on.

Professor Jian and Dr Jie added: ‘These findings strongly support an urgent need for further immediate, comprehensive studies that combine genomic data, epidemiological data, and chart records of the clinical symptoms of patients with coronavirus disease 2019 (COVID-19).’

The study was published in the scientific journal National Science Review, which is managed by the Chinese Academy of Sciences.

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