World's biggest study on Covid-19 shows early deaths among Indians, higher risk of infection in vehicles

The world’s largest study on Covid-19 cases in India has pointed to early deaths – within six days after detection – and a hugely inflated risk of infection while sharing a vehicle with an infected co-passenger.

Carried out on nearly 85,000 positive cases in Tamil Nadu and Andhra Pradesh and their 5,75,000-plus contacts, the research found that the oldest adults were surprisingly protected from exposure to the infection, but children up to 14 years of age carried a significant risk of picking up the infection from their friends.

Analysing the mortality trend in a smaller subset of around 1,25,000 people, it reported that half of the corona-positive people died within six days of testing and in case of 1,024 individuals, the death came within less than 24 hours of getting detected as Covid-19 positive.

In contrast, in the USA the average time-to-death from the day of hospital admission was 13 days, whereas the World Health Organization had estimated that it would be anywhere between two to eight weeks relying on Chinese data.

"Our observations likely indicate a substantial portion of patients in Tamil Nadu and Andhra Pradesh are diagnosed late in their disease course,” the team comprising researchers at Princeton University; University of California, Berkeley and Johns Hopkins Bloomberg School of Public Health reported in the journal Science on Wednesday.

The researchers – assisted by government officials from Tamil Nadu and Andhra Pradesh – found that only 9% people pick up the infection from a positive person within a household, but the number rises to 79.3% - nearly nine times more – if a non-infected individual travel for more than six hours along with a Covid-19 positive person in a shared vehicle.

“The largest Covid epidemiology in the world confirms that Indians between the ages of 40 to 70 face much higher risks from the disease than do people of similar age groups in other countries. We also found evidence of super-spreading – that just 8% of the infected population was responsible for 60% of the secondary infections,” principal investigator Ramanan Laxminarayan from Princeton University told DH.

“These findings, both representing the capacity of science in India to inform the global response on Covid, also emphasize the need for more such studies in other states like Kerala and Maharashtra to inform state and national strategies.”

Close examination of the mortality data from the two southern states also revealed that nearly 18% of those who died are individuals with an age of 75 years and above. In comparison, 58% of deaths in the USA are people in the same age bracket.

In the two southern states, mortality plateaued at ages 65 years and above in contrast to observations in the USA.

“While the role of children in transmission has been debated, we identify high prevalence of infection among children who were contacts of cases around their own age,” they reported.

Incidentally, the findings came out on the same day when the Centre left it to individual states to decide on the reopening of schools in a graded manner rather than imposing a blanket ban.

The most prevalent conditions among those who died were diabetes, sustained hypertension, coronary artery disease, and renal disease, with at least one comorbid condition noted among 62.5% of fatalities, in comparison to 22% of fatalities in the United States as of May 30, 2020.

The study underscores the importance of generating epidemic data from India, which has the world’s second largest caseload of corona-positive cases for tailoring country-specific public health interventions.