A study published Dec. 28 in Experimental Physiology says that when taking your temperature measurements for COVID, you should be doing so in two different places: your finger and your eye. The reason you need these two measurements is because you should be measuring your deep, core body temperature. According to the researchers, even a 1 degree increase in deep body temperature could “indicate the onset of fever by a viral infection.” And while there are several ways to directly measure core body temperature, they are too expensive, invasive, and time consuming to be widely used in public settings. This is why researchers recommend measuring two sites for the most accurate deep body temperature estimate—one central and one peripheral. According to the study, the reason the eye is favored over the forehead for central temperature is because it produces the highest temperature, and the same goes for the fingertips in terms of peripheral temperature. And for more up-to-date information, sign up for our daily newsletter. The problem with measuring only the forehead is that it only measures someone’s surface temperature. And this can “fluctuate independently” from the core body temperature, according to the researchers. “Using a surface temperature scanner to obtain a single surface temperature, usually the forehead, is an unreliable method to detect the fever associated with Covid-19,” study co-author Michael J. Tipton, PhD, a professor at the University of Portsmouth, said in a statement. “Too many factors make the measurement of a skin temperature a poor surrogate for deep body temperature; skin temperature can change independently of deep body temperature for lots of reasons. Even if such a single measure did reflect deep body temperature reliably, other things, such as exercise, can raise deep body temperature.” And for more on fevers, These Are the Worst Things You Can Do if You Have a Fever. As we know, the coronavirus can present in many different ways. And while an early Feb. 2020 study from China found that a fever was the most common symptom in COVID patients, it is possible for someone to have the coronavirus and not have a fever. In fact, researchers from the December study said that at least 11 percent of coronavirus patients never have a fever, and even those who go on to exhibit this symptom later in their illness can “be contagious several days before the onset of fever.” Therefore, a temperature check alone may not be the best indicator of COVID. And if you’re worried about getting sick, This Strange Symptom Could Be the Only Sign You Have COVID, Study Says.ae0fcc31ae342fd3a1346ebb1f342fcb If you have a fever, that doesn’t necessarily mean you have the coronavirus. This is especially true when relying on just a forehead temperature scan to detect a fever. As the researchers note, someone’s surface temperature can rise on their forehead due to a number of factors that may not be infection, such as “ambient temperature, exercise, alcohol consumption, food consumption, sunburn, and various skin conditions.” And for more coronavirus symptoms to look out for, discover The Earliest Signs You Have COVID, According to the Mayo Clinic.