Coronavirus has mutated into two strains, one which appears to be far more aggressive, scientists have said, in a discovery which could hinder attempts to develop a vaccine.

Researchers at Peking University's School of Life Sciences and the Institut Pasteur of Shanghai, discovered the virus has evolved into two major lineages - dubbed ‘L’ and ‘S’ types.

The older ‘S-type’ appears to be milder and less infectious, while the ‘L-type’ which emerged later, spreads quickly and currently accounts for around 70 per cent of cases.

Genetic analysis of a man in the US who tested positive on January 21, also showed it is possible to be infected with both types.

The finding comes just days after government health experts warned that the virus could hit Britain in ‘multiple waves’, and led to fears that some vaccines might not work on mutated strains.

Dr Stephen Griffin, of the Leeds Institute of Medical Research and chair of the virus division at the Microbiology Society, said that two of the changes between the ‘S’ and ‘L’ lineages were in crucial protein called ‘spike’, which plays a key role in the infection process and is a target for vaccines.