Researchers have found that people living in higher altitudes, especially 3,000 meters (9,842 feet) above the sea level are less likely to get infected with COVID-19 as compared to their lowland counterparts.
The Washington Post quoted a peer-reviewed study, published in the journal Respiratory Physiology & Neurobiology, in which researchers from Australia, Bolivia, Canada and Switzerland review the epidemiological data from Bolivia, Ecuador and Tibet. The study concluded that Tibet’s infection rate was “drastically” lower than that of lowland China, three times lower in the Bolivian Andes and four times lower in the Ecuadoran Andes.
Cusco in Peru, a picturesque Andean valley, the high-altitude city of 420,000 residents, had recorded only three death of tourists from Mexico, China and Britain, at the start of Peru’s strict national lockdown. Since then, there has not been any other COVID-19 fatality in the entire region, even as the disease has claimed more than 4,000 lives nationally. The rate of infection has also remained low. Just 916 of Peru’s 141,000 cases come from the Cusco region. It is being estimated that coronavirus gets ‘soroche’ (the Quechua word for altitude sickness) at higher-altitude.
Similarly, Ecuador has suffered one of Latin America’s worst outbreaks, with more than 38,000 reported cases and more than 3,300 deaths, according to official figures. But it has been centred on the Pacific port of Guayaquil. Bolivia’s 8,387 cases have been concentrated in the department of Santa Cruz, just a few hundred feet above sea level. But the department of La Paz, home to the world’s highest capital, has had just 410 cases.
The researchers hypothesize that people living at high altitudes might be benefiting from a combination of an ability to cope with hypoxia (low levels of oxygen in the blood) and a natural environment hostile to the virus — including dry mountain air, high levels of UV radiation and the possibility that lower barometric pressure. All these things reduce the virus’s ability to linger in the air, the media reported further.
Just three regions in the world have found to have genetic adaptations to altitude: Himalayans, Ethiopian highlanders and Andeans. Yet Clayton Cowl, a pulmonologist at the Mayo Clinic and a former president of the American College of Chest Physicians, suspects the trend may be more closely related to acclimatisation, the body’s ability to adjust temporarily to altitude, than to DNA.
Cowl notes that prolonged exposure to altitude triggers a chain reaction in the lungs involving a protein known as ACE2 that might prevent pulmonary shunting, a problem common among COVID-19 patients.
Generally, when a part of the lung is damaged, the body redirects the flow of blood toward healthier areas that can absorb oxygen in a better way. Shunting stops that process of redirection, resulting in hypoxia. It is, according to Cowl, a common element reported among 30 per cent of COVID-19 patients who exhibit mild symptoms yet have unusually low levels of oxygen in their blood — and who sometimes take a sudden turn for the worse.
But researchers are still looking for more evidence to establish the link between the two.
“The virus likes people. It doesn’t care about altitude,” says Peter Chin-Hong, a researcher on infectious diseases from the University of California in 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.