As the Delta variant of COVID-19 continues to spread around the world, scientists are discovering why the strain is so contagious.
The variant is surging around the globe and the World Health Organisation has warned it is quickly becoming the world's most dominant strain of COVID-19.
Preliminary data also suggests children and adolescents are at greater risk of becoming infected with and transmitting the variant.
The strain was first detected in India and has since spread to almost 100 other countries.
Now, a new study shows people infected with the variant have about 1000 times more copies of the virus in their respiratory tracts compared to people infected with the original strain of COVID-19.
Scientists at the Guangdong Provincial Center for Disease Control and Prevention looked at the level of the virus in patients infected with the first outbreak of the Delta variant in mainland China, in May and June. They then compared those levels with patients who had an earlier strain of the virus in 2020.
The researchers found the viral loads in the Delta infections were around 1000 times higher that those in the earlier strain infections on the day when viruses were first detected.
They also found people infected with the Delta strain are also more likely to become infectious sooner, with the Delta variant taking about four days to reach detectable levels compared to six days in the original strain.
