Asymptomatic TJ cluster spurs research on virus strain in TN

Pushpa.Narayan@timesgroup.com

Chennai:04.04.2020

Curious over why more than 80% of the participants of the Tablighi Jamaat conference in Delhi who tested positive show no symptoms, the Tamil Nadu health department has asked virologists to study the strain and its virulence.

“We have isolated and tested almost all those who participated in the conference. Many who tested positive show no signs of having the virus,” said health minister C Vijayabaskar. “And others have only mild symptoms. We see this outside the cluster as well. So far, we have had one death. They respond to antiviral drugs; didn’t require ventilators,” he said.

Experiences shared by experts from other states with Tamil Nadu differed considerably. “We don’t know why Maharashtra had more than 40 deaths and Kerala had more than 30,” he said Scientists from health and veterinary sciences departments will study if the virus had mutated to be less virulent in the region. Researchers will collect data from samples from infected patients and their families and neighbours. “It can give us important information in our fight and help us prevent the spread,” said Vijayabaskar, a doctor himself. Experts from across the globe are sequencing the virus’s genome to monitor changes.

Too early to study strain as cases yet to peak, says expert

The Covid-19 Genomics UK Consortium has been given £20 million for the project. Scientists in the US, Spain and Italy have also been working on the genetics of the virus.

“All viruses mutate over time, some faster than others,” said Dr V Ramasubramanian, infectious disease consultant at Apollo Hospitals. “Covid-19 is a very young one on the list. There is no evidence to show the strain we see here is different,” he said. Nevertheless, as a practicing physician, he no longer sees fever, a dry cough and fatigue as tell-tale symptoms of the infection. “I see patients with no cough having a bad congestion. Some of them even tolerate low oxygen saturation,” he said.

The matter of asymptomatic Covid-19 patients was discussed at the task force meeting chaired by chief secretary K Shanmugam on Friday. “It is important to study if there is a reattachment or modification in the virus we see among the clusters here,” said former city health officer Dr P Kuganandham, a member of the task force.

Asymptomatic transmission isn’t new. “While it is good to study, it may be too early to celebrate. We are not yet at the beginning of the peak we are going to see,” said a senior virologist at Christian Medical College in Vellore. Predictions done by the health department using mathematical models estimate we may have up to 1lakh hospitalisations during the peak period.

WHO chief scientist Dr Soumya Swaminathan said while children in several Chinese households remained asymptomatic transmitters, some can be presymptomatic. These are people who unwittingly spread the virus before they have symptoms. Scientists in Japan pointed out that this presymptomatic transmission is happening at a more rapid rate now than it did during SARS.

Health secretary Beela Rajesh said the department is taking no chances. All people in quarantine will remain there for 14 days, she said. “We are working out containment plans, tracking epidemiological graphs and studying the virus. Our doctors, beds, ICUs and ventilators are on standby. We just hope we don’t have to use them,” she said.