Coronavirus symptoms can look like the flu, a cold, allergies, even acute mountain sickness. What should climbers know about false positive rapid COVID tests at high altitudes?

COVID has given us a lot to think about. We learned coronavirus symptoms look like the flu, a cold or even allergies. But, now, we are learning about COVID tests and the questions they raise.  

[Related Reading: Not All Symptoms Lead to Coronavirus]

It was thought all COVID tests were created equal. Later, we learned that proctored tests were better for travel and home tests were acceptable for employment or school, sometimes. And now, following the mountain climbing season in the Himalaya and Karakoram ranges, which include Mount Everest, Broad Peak Mountain and K2, we are discovering cold weather can lead to false positives for COVID-19.  

Mountaineers needing medical assistance are — sometimes testing positive for COVID-19 while at high altitudes in cold weather. But later, these same mountaineers test negative for the disease when they arrive at a medical facility and receive a PCR test.  

“There were several COVID cases during the spring 2022 climbing season in the Himalaya and Karakoram regions. Some were true COVID cases, while others were acute mountain sickness, HAPE, HACE or the flu,” said David Koo, the associate director of operations for Global Rescue and a former combat medic and emergency nurse who was deployed to Nepal for the climbing season.  

COVID Symptoms for a German Mountaineer

A German Global Rescue member who was mountain climbing needed a helicopter field rescue from Broad Peak, the 12th-highest mountain in the world, located in the Karakoram on the border of Pakistan and China. It rises 26,414 feet/8,051 meters above sea level. Broad Peak is a challenging, steep climb with dangerous upper sections and a summit ridge that has turned back some of the best mountaineers, according to climbing expert Alan Arnette. “It is not an easy mountain,” he said.  

During an ascent from 13,779 feet/4,200 meters to 16,404 feet/5,000 meters, the member declared he was weakening, but pushed forward, according to the expedition leader. Unfortunately, his condition worsened. By the middle of the section trek, he felt frail and could not walk. He was placed on a donkey until they reached the Broad Peak base camp at 16,404 feet/5,000 meters.  

By then, the member had a severe cough, a fever of 102.56° F/39.2° C, an oxygen saturation level of 75% and was unable to fully sleep or eat well. He tested positive for COVID-19 using an antigen kit. The expedition leader contacted Global Rescue and an airborne medical evacuation was initiated.  

The member was transported to a hospital in Skardu, where he was evaluated and diagnosed with acute mountain sickness and given antibiotics, IV fluids, nebulization and medication for the fluid in the lungs while at the hospital. He was re-tested for COVID-19 using a PCR test, which was negative, unlike the result given to him at more than 16,000 feet/5,000 meters on Broad Peak Mountain where the temperatures dip well below freezing (1° F/-17° C) and even lower with the wind chill factor (-15° F/-26° C). 

Why False Positive?


What causes a false positive rapid COVID test? Does altitude affect the efficacy of a COVID-19 test? Does cold weather do the same?  

“Most of the at-home tests authorized by the Food and Drug Administration (FDA) should be stored at 35° F (1.6° C) or above. Below that temperature, the testing liquid can freeze, potentially decreasing its effectiveness,” according to a report in VeryWellHealth. 

COVID-19 test makers account for weather changes, according to the FDA. The tests should be performed in temperatures around 59–86° F (15–30° C).  

“Since shipping conditions may vary, test developers perform stability testing to ensure that the test performance will remain stable when tests are stored at various temperatures, including shipping during the summer in very hot regions and the winter in very cold regions,” according to the FDA 

For example, BinaxNow tests recommend storing the tests at 35.6–86° F (2–30° C). Ellume advises users to keep their tests at 59–95° F (15–35° C). Both must be used at room temperature, generally 70° F (21° C). 

Tests kept outside in cold temperatures are likely to lose some effectiveness. If it’s cold out, let the unopened test sit inside for at least two hours until it reaches room temperature, according to the FDA.  

“If a test kit is exposed to extreme temperatures, if you’re in the Rockies or the Himalayas for example — anywhere it’s below freezing — the results may not be reliable.  You may want to repeat the test and also monitor yourself for symptoms. As a guide, we do not rely only on test results to determine your medical condition.  A medical professional will review the result with accompanying signs and symptoms,” Koo said.  

Some rapid antigen tests are delivered and left outside someone’s home or workplace before the owner can pick them up. If the weather is cold, will your test kit be damaged? Probably not.  

“If you’re in a part of the world where the temperature dipped to 35° F (2° C) after the carrier dropped it off and [it] didn’t get colder, just let it warm up to room temperature and there really shouldn’t be any issues with it,” according to Michael Blaivas, MD, FACEP, FAIUM, an emergency physician and chief medical officer at Anavasi Diagnostic. 

Unlike in cold temperatures, rapid antigen COVID tests do not fare well in extreme heat and may be irreversibly damaged. “Storing at higher temperatures means proteins in the tests can be denatured — permanent changes to protein structure, just like when you cook an egg,” according to a report 

When In Doubt, Call Us


So far, there is no evidence that high altitude decreases the efficacy of an antigen test. But heat can permanently ruin a test kit. Cold weather can diminish a test’s accuracy but letting the kit contents warm up to room temperature should restore its efficacy.  

[Related Reading: Mission Briefs April The Himalayas Special Edition] 

Not certain about your COVID test? Medical advisory services are included with every Global Rescue travel protection services membership. Global Rescue’s member services team is available 24/7/365 triaging calls and getting medical questions immediately to the Global Rescue medical operations team.  

“Global Rescue’s medical advisory service is here to answer questions and provide guidance for our members’ concerns,” said Garret Dejong, senior specialist in medical operations at Global Rescue. “No request is too small. Call us whenever you have a medical question during your travels. Ask immediately to protect against things getting worse.”