Joaquin Azpilicueta, M.D.

Viral infections tend to have common symptoms and signs that help the diagnosis and early care but they show differences among individuals that can be deceptive. They can also show differences as they mutate. Some of us might show more symptoms from the upper respiratory airways or digestive or lung, etc. In the case of Omicron we see less lung infection, less neurologic symptoms (loss of smell and taste), more upper airways or gastroenterological involvement (cough, vomiting…)


We are going to see how and why taking our temperature is an easy and effective way to add security for ourselves and our community in this pandemic.

Viruses might tend to become endemic, i.e., “cohabitate” with a population due to vaccination and herd immunity; then these interindividual differences are higher both in kind and intensity. This seems to be the trend we are seeing in this wave of the Omicron variant, a set of “decoupled” curves with a disproportionate relationship between cases as compared with hospitalizations or deaths.

The main issue with Omicron is its enormous transmissibility. Overall, the severity and mortality are much less important in proportion to the number of cases, but as the number of cases is so high, every health care system risks to be put in high stress if we don’t control the transmission and reduce as much as we can the number of cases. In other words, we need to protect ourselves to protect the others.

We know what to do: get vaccinated, keep the social distance and use the protection tools, especially the masks. All this is necessary but not sufficient: we should check our symptoms and perform self-tests to make sure we detect as early as possible an infection and take the proper action.

Antigen Self-tests are a key method of surveillance but, as any test in medicine, they are not perfect. This means that they can have false negative results; when they are positive, we know we are infected for sure, but a negative test is not a warranty of not being infected. These false negative results tend to happen precisely in the early days of the infection (2-3 days) because the result depends on what is called the “viral load”, i.e., the “number” of viruses present in the body. You can find a very clear and educational infographic explanation of the value of tests in this link:

During these early days of the infection, when the test might be frequently negative, most often the patient has symptoms. Acting early is key to contain the spread of the virus and to protect ourselves seeking care early.

Loss of smell and taste was one of the most perceptive and alarming symptoms of the Covid19 infection but the Omicron variant is affecting less the neurologic system ( Hence, fever, cough and tiredness are the 3 main early symptoms that can trigger the alert (

Thermometry is and has been a key element for early detection of infected people. Unfortunately, not all thermometers are equally effective and the non-contact thermometers have been massively used in an ineffective and inefficient manner. Non-contact thermometers have been proven to be useless as a screening tool (Sullivan, S.J.L., Rinaldi, J.E., Hariharan, P. et al. Clinical evaluation of non-contact infrared thermometers. Sci Rep 11, 22079 (2021) Nature Briefing.

Measuring our temperature frequently is a key piece of the protective measures that we need to observe. Acquiring an accurate, reliable, easy to use, noninvasive thermometer is an effective and efficient investment in our health and our beloved ones’.