Scientists are now investigating the link between COVID-19 and high altitude regions like Tibet after a study published in the journal Respiratory Physiology and Neurobiology suggested that there is a decrease in prevalence and impact of COVID-19 in populations living at higher altitudes.
The study takes into consideration the COVID-19 cases in Tibet and high-altitude regions of Bolivia and Ecuador in comparison to the low lying regions. It suggested that the population in Bolivia, Ecuador and Tibet living above 3,000 meters (9,842 feet) reported significantly lower levels of confirmed infections than their lowland counterparts.
In the plateau region of Tibet, Qinghai and part of Sichuan, with a population of 9 million, there are only 134 confirmed cases which are drastically low in comparison to the number of cases in rest of China.
Ecuador is one of the worst-hit countries by COVID-19 in South America with more than 40,000 confirmed cases and over 3,000 deaths. The centre of the virus is the Pacific port of Guayaquil. There are fewer infected cases in the capital Quito, which is about the same size but is 2,800 metres above sea level.
Similarly, Bolivia has over 10,000 positive cases with over 300 deaths. The cases are concentrated in Santa Cruz which is 400 metres above sea level. It is home to about 15% of the population of the country but accounts for two-thirds of the virus cases. Whereas, in La Paz and its surrounding area, which is a highland area in Bolivia, has about 500 positive cases.
The reason explored by the study includes environmental factors including dry mountain air, high levels of UV radiation and the possibility that lower atmospheric pressure reduces the virus’s ability to linger in the air.
“The reason for decreased severity of the global COVID-19 outbreak at high altitude could relate to both environmental and physiological factors,” states the study.
“At sea-level, when people get coronavirus and their lungs get destroyed, it is as if they are climbing Mount Everest in just a couple of days, without oxygen,” said Gustavo Zubieta-Calleja, one of the authors of the study published in the journal Respiratory Physiology & Neurobiology. But “the low rate of infection in Bolivia’s high-altitude population is remarkable and clearly does not follow the often exponential infection rates reported in many countries”, concluded the scientists.
However, experts have questioned these factors. “The virus likes people. It doesn’t care about altitude,” says Peter Chin-Hong, who studies infectious diseases at the University of California at San Francisco. “But we’re still learning so much about this disease, and this does provide us with some good clues to try and understand its progression,” he added.
According to Clayton Cowl, a pulmonologist at the Mayo Clinic and a former president of the American College of Chest Physicians, that the trend might be related to acclimatization, the body’s ability to adjust temporarily to altitude, than to DNA.
Just three populations in the world have been found to have genetic adaptations to altitude: Himalayans, Ethiopian highlanders and Andeans. This is why the coronavirus is exploding on Peru’s Pacific coast, particularly Lima, where most residents descend from Andean ancestors, while the country’s mountain communities are thus far not greatly affected by the virus.
Andrew Luks, professor of medicine at the University of Washington, said that while the proposed link was “intriguing”, it “by no means establishes that high-altitude residence or high-altitude locations are protective against coronavirus”.