Indian ‘Delta’ Covid variant is spreading so fast because it makes copies of itself faster in the body and causes symptoms to appear earlier than previous mutated strains, study finds
- Researchers in China looked at 62 COVID-19 patients during the first outbreak of the Indian ‘Delta’ variant in Guangzhou in 2021 with 63 patients infected in 2020
- People infected with Delta had 1,000 times more copies of the virus in their respiratory tract than people infected with the original strain
- The incubation period was also shorter in Delta patients, who showed symptoms after four days compared to six days for those with the original virus
- It explains why the Delta variant has overtaken the US so quickly, from 10% of cases in mid-June to 83.2% of all new infections in mid-July
Scientists have discovered why the Indian ‘Delta’ variety is more contagious and has spread so quickly around the world.
Researchers at the Guangdong Provincial Center for Disease Control and Prevention in China looked at people infected with the mutation, also known as B.1.617.2.
They found that it makes copies of itself faster and has a shorter incubation period than previous species.
It explains how the Delta variant has overtaken the U.S. exponentially, from 10 percent of all cases by mid-June to 83.2 percent of all new infections by mid-July, according to the Centers for Disease Control and Prevention (CDC).
People infected with the Delta strain had 1,000 times more copies of the virus in their respiratory tract than people infected with the original strain (above), a new study finds
The incubation period was also shorter for Delta patients, who showed symptoms after four days compared to six days for those with the original virus (above)
The variant, first identified in India in September, has been labeled a “double mutant” by the Indian Ministry of Health because it carries two mutations: L452R and E484Q.
L452R is the same mutation seen in the homegrown California variant and E484Q is similar to the mutation seen in the Brazilian ‘Gamma’ and South African ‘Beta’ variants.
Both mutations occur in key parts of the virus that allow it to invade and infect human cells.
For the study, which was published online earlier this month, the team looked at 62 COVID-19 patients during the first outbreak of the Delta variant in Guangzhou, the capital of Guangdong province, between May 21 and June 18.
Researchers compared their levels of the virus with 63 patients infected with a previous strain in 2020.
They found that when the Delta variant infects someone, it makes copies of itself more quickly – causing it to spread throughout the body –
People who infected the mutation had a viral load that was 1,000 times higher than . meaning they had 1,000 times as many specimens in their respiratory tract as people infected with the original strain.
The incubation time, i.e. the time between exposure to infection and the onset of symptoms, was shorter in the mutant.
The study found that when someone got sick with the Delta variant, it only took about four days to show signs such as coughing and fever.
In comparison, when infected with the original coronavirus, it took about six days for the infection to be discovered.
It explains how the Delta variant has overtaken the US so quickly, from 10% of all cases in mid-June to 83.2% of all new infections in mid-July
Their results confirm that the Delta variant is spreading two to three times faster than the original virus that emerged in Wuhan in December 2019.
‘[The higher viral load] stresses that more infectivity of Delta variant during the early stage of infection is very likely, and the frequency of the population screening should be optimized for the intervention,” the authors wrote.
“The more contagiousness of the Delta variant infections in the presymptomatic phase emphasizes the need for timely quarantine for the suspected cases of infection or close contact before clinical onset or PCR screening.
“These data indicate some benefit or neutral mutations, even at a low frequency, could potentially increase and become fixed in one generation of transmission, and further predominate in the virus population if the epidemic cannot be properly controlled.”