COVID 19 Term result of coronavirus and WANTse contraction, disease in English and suffix 19 in reference to the year 2019 in which it was discovered as a ZOONOSIS or human pathology derived from an animal species. In turn, covid 19 is an apheresis of SARS-CoV 2, which is the scientific name of the coronavirus that has become epidemic and then a pandemic. This name is because the symptomatology was initially similar to the 2003 SARS-CoV and the 2012 MERS-CoV. Other ailments attributable to the disease have appeared. Covid 19 is a protein (and not a living being) that to reproduce needs the human cell. How do you do that? By assembling to proteins that are on the surface of the cell, called RECEPTORES which achieves with the appendages located in the lipid membrane of the virus, which make up its crown. This allows the virus to penetrate into the cell, which, deceived, begins to massively reproduce the virus. In 28 cycles it can generate 1 . 000 . 000 . 000 viral particles. The PCR test, (Polymerase Chain Reaction) which is used, among many other tests, to determine if a person is infected, does something similar, requiring time to achieve cycles that create a sufficient viral load that rely on not resulting in a false negative. So far 2 receptors have been found that covid 19 can use to infect us: the first of which is ACE2, which is the one used by SARS-CoV of 2003. ACE2 requires another protein to perform its function: a protease, the enzyme TMPRSS-2, which, in turn, processes another protein that protrudes from the contour of the virus (the protein S or Spike, spike) and that gives it the appearance of star or crown. The viral protein S is thus recognized by ACE2 and then the virus enters the cell. ACE2 is widespread: from the cerebral cortex and hypothalamus to the muscle and, although present in lung cells, there is more ACE2 in the testicle, kidney, gallbladder, blood vessels, endocrine organs and, above all, in the digestive tract, from the mouth to the rectum, with the highest concentrations in duodenum and small intestine. This dissemination is due to ACE2 developing important physiological functions, such as regulating blood pressure by transforming the hormone vasoconstrictora angiotensin II into the vasodilator angiotensin 1-7. A second receiver described recently is CD147, also called basigina or EMMPRIN ( 8 ). CD147 is an important protein for cell recognition, for example, during gametogenesis and nervous system development, as well as for blood group determination. One of its denominations is due to the induces the production of proteases that help destroy the extracellular substance, the material that gives consistency to our tissues. The distribution of this molecule is ubiquitous! . It is found in lungs, but with greater abundance in many other organs such as those of the central nervous system, endocrine glands, liver and gallbladder, kidney, pancreas, muscle and, again, especially in the digestive tract. The CD147 has affinity with the same protein S of the virus surface as ACE2, but it is unclear whether both receptors are equally important or if CD147 is secondary. For the reasons exposed, people with chronic basic pathologies, such as diabetes, hypertension, renal failure and respiratory conditions are permanently aggravated and many, if they are over 70, end up dying.