HYDERABAD: Asymptomatic Covid-19 persons carry much higher viral load than symptomatic cases and could be the reason behind the fast transmission of the infection in the country, a study by researchers from Hyderabad-based Centre for DNA Fingerprinting and Diagnostics (CDFD), in collaboration with the National Centre for Biological Sciences (NCBS) and Nizam’s Institute of Medical Sciences (NIMS) has found.
The significant finding adds a new dimension to the discussions over high infection rate and low mortality of Covid-19 patients in India and whether asymptomatic Covid-19 patients can spread the infection.
CDFD is one of the testing centres in Hyderabad for samples collected from suspected symptomatic and asymptomatic Covid-19 patients.
For the study, the researchers analysed more than 200 samples of the novel Coronavirus and their genomic sequences. They found that samples collected from asymptomatic cases had much higher viral load (low Cycle threshold value) than the samples collected from symptomatic cases of Covid-19. A majority of Covid-19 cases detected are asymptomatic. Even in the case of CDFD, most of the samples they received were of asymptomatic persons.
As the asymptomatic Covid-19 patients are high in number and according to CDFD study, they carry higher viral load than symptomatic patients, it is possible that the transmission of virus from asymptomatic patients is also occurring and that too at a high rate. Moreover, as the asymptomatic cases are high, death rate is expected to be low.
Unique mutations of virus found in TS
Researchers also report that most of the novel Coronavirus samples belonged to one major clade (group, in layman’s terms) -- 20B and two minor clades -- 19A and 20A.While the 19A is related to the virus from Wuhan, China, the 20A clade is related to the dominant strain from Europe.However, majority of the samples since April, belong to the 20B clade, a mix of various strains with mostly from asymptomatic cases.
Analysing genome sequences of novel Coronavirus samples from Telangana, the researchers found the presence of unique mutations in the virus. However, they said further studies need to be conducted to find out what exact impact they have. These findings have been published in the preprint paper - ‘Mutational landscape and dominant lineages in the SARS-CoV-2 infections in the state of Telangana, India.’ Attempts by Express to elicit a response from CDFD yielded no results.