COVID-19, caused by the SARS-CoV-2 virus, has presented a wide array of symptoms, with changes in body temperature being a notable aspect of the illness. Understanding how this virus interacts with the body’s thermoregulation system is important, as temperature shifts can be both a common indicator of infection and a more prolonged, challenging issue for some individuals. These temperature changes are not always straightforward fevers and can manifest in various ways, influencing how individuals experience the disease.
How the Body Regulates Temperature
The human body maintains a stable internal temperature, around 37°C (98.6°F), through a process called thermoregulation. This system is controlled by the hypothalamus, a region in the brain that acts like a thermostat. The hypothalamus monitors the body’s temperature and makes adjustments to keep it within a healthy range.
When the body needs to cool down, the hypothalamus triggers processes like sweating and vasodilation, where blood vessels near the skin surface widen to release heat. Conversely, if the body is too cold, it initiates shivering to generate heat and vasoconstriction, narrowing blood vessels to conserve warmth. This balancing act, involving the skin, sweat glands, and blood vessels, ensures cellular functions operate optimally.
Common Temperature Manifestations in COVID
A common temperature-related symptom during acute COVID-19 infection is fever. A fever indicates a body temperature of 38°C (100.4°F) or higher. This elevated temperature helps the body’s immune system create an inhospitable environment for the virus and activate its defenses.
Chills are also common, often experienced as the body’s core temperature rises rapidly. Not everyone with COVID-19 will develop a fever. The presence and severity of fever can vary. A very high fever (40°C or higher) has been associated with more severe outcomes.
Beyond Fever Atypical Temperature Experiences
Beyond acute fever and chills, COVID-19 can lead to prolonged temperature regulation issues. Some individuals experience persistent low-grade fevers, where their temperature remains slightly elevated for an extended period after the acute phase. These elevations can be confusing and contribute to ongoing feelings of unwellness.
Temperature fluctuations are also reported, where individuals might feel unusually hot or cold without a measurable fever. This dysregulation can include feeling warm to the touch or having chills, despite a normal thermometer reading. Such experiences highlight a disruption in the body’s internal temperature control mechanisms. These atypical temperature sensations, including heat intolerance, are recognized as symptoms of long COVID.
Underlying Mechanisms of COVID’s Impact
COVID-19’s impact on body temperature regulation involves an interplay between the virus and the host’s immune response. The SARS-CoV-2 virus can trigger an inflammatory response, leading to the release of signaling molecules called cytokines. These inflammatory mediators can interact with the hypothalamus, the brain’s thermoregulatory center, resetting the body’s temperature set point higher.
This cytokine-hypothalamus interaction can lead to the production of pyrogens, substances that signal the brain to raise body temperature, resulting in fever. Additionally, the virus may directly affect the hypothalamus, impairing its ability to adapt to temperature changes and disrupting thermoregulatory pathways. This direct and indirect influence on the hypothalamus can contribute to fluctuations and dysregulation of body temperature, including abnormally low body temperature, which has been associated with severe cases and poorer outcomes.