Study Finds High Rate Of Lung Damage In Indians After Acute Covid, Experts Decode Why

The study by the Christian Medical College, Vellore, is the largest from India to investigate the impact of COVID-19 on lung function. It examined 207 individuals, showcasing substantial impairment in lung function, exercise capacity, and quality of life among recovered individuals.

The study revealed a high prevalence of respiratory symptoms among Indians who recovered, even after a mean of over two months following acute illness, with shortness of breath reported in 49.3 per cent and cough in 27.1 per cent of the cohort.

“It is clear from the study that lung function is affected more in the Indian population compared to data from other countries across every category of disease severity,” said study lead researcher D J Christopher, professor of pulmonary medicine at CMC Vellore.

“Although it is impossible to know the exact cause of worse impairment among Indians, co-morbidities may be a factor contributing to lung damage, as our population had much higher co-morbidities than the others ” Christopher told PTI.

The study, published recently in the journal PLOS Global Public Health, compared data from Europe and China. An Italy-based study, for instance, found dyspnoea or shortness of breath present in 43 per cent and cough in less than 20 per cent of the subjects. The corresponding figures from a Chinese study were also lower than those seen in the Indian study. 

However, the CMC study did not cite any specific data from China or from European countries other than Italy.

In terms of co-morbidities, CMS Vellore researchers found 72.5 per cent of individuals reporting underlying health conditions such as diabetes mellitus, systemic hypertension, and chronic lung diseases.

Lung function tests revealed a concerning trend of impairment, particularly in diffusion capacity (DLCO), a sensitive test to assess the lungs' ability to transfer gas from inspired air to the bloodstream, the researchers said.

Nearly half (44.4 per cent) of the participants showed impaired diffusing capacity, with rates of impairment being higher in those with more severe Covid infection. Therefore, those who needed invasive or non-invasive ventilation and had recovered had the worst lung function impairment.

Reacting to the study findings, Delhi-based pulmonologist Vivek Nangia said the most unique feature that predisposes Indians to greater damage to Covid or disease-induced lung injury could be a high prevalence of tuberculosis in the country, which is weakening our immune system and also damaging the lungs.

India accounts for about 25 per cent of the global TB burden, with an estimated disease incidence of 2.77 million in 2022, according to a study published last year in the Journal of Infection and Public Health.

However, Christopher said none of the study subjects had features of active TB at the time of recruitment to the study.

“A second factor that could explain the worse lung damage is the air pollution, which of course is reducing our immunity and damaging the lungs,” Nangia, principal director and head of pulmonology, at Saket’s Max Super Speciality Hospital, Saket, told PTI.

Deepak Sharma, consultant pulmonologist, Ujala Cygnus Group of Hospitals, Delhi agreed.

“Access to quality healthcare during and after the infection can influence recovery outcomes. Also, pollution, particularly in densely populated areas, could exacerbate respiratory issues and hinder recovery,” he told PTI.

Although the study sample is small, he added, several factors could contribute to these outcomes, including the severity of the infection.

“Those with severe Covid cases may experience more pronounced long-term effects on lung function and overall health. Individuals with pre-existing respiratory conditions or other co-morbidities may make patients more susceptible to lasting effects from the virus,” Sharma said.

While pollution is likely a contributing factor, the experts noted that other variables such as genetics, lifestyle factors, and healthcare infrastructure also play crucial roles.

“In the future what we're going to see is a significant rise in the number of cases of respiratory diseases. This could be in terms of interstitial lung disease, could be in terms of lung cancer, in terms of respiratory infections,” Sharma said.

“Even now what we're seeing is that minor viral infections are turning into very severe kind of illnesses requiring hospitalisation, ICU care and are even resulting in mortality,” he added.

Extrapolating the findings of his study, Christopher noted that in the long run, these patients might end up with lungs that function less than optimally.

“The impact on their lung function may improve for up to one year, but some patients may have to live with scared lungs all their lives. If the impairment is relatively smaller, they will carry on with normal activities of life but it may limit their exercise capacity. If it is severe it may become an impediment on a daily basis straight away and a few may be oxygen dependent,” he added.

Addressing these factors requires a multi-faceted approach, including improving healthcare access, reducing pollution levels, and implementing targeted interventions for at-risk populations, the doctors said.

Nangia said the implications of the study reveal potential long-term health challenges for Indians who have recovered from Covid, including lung function impairment and lingering symptoms.

“This suggests a need for comprehensive post-recovery care and monitoring to address these issues,” he explained.

How does one decrease the risk of disease?

Regular exercise and yoga, Nangia said.

Appropriate vaccinations may reduce lung infections and thus offer protection, Avoiding air pollution outside can help, he added.