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ing to perform. Reassuringly, SARS-CoV-2 doesn’t seem to be present in semen (Guo L 2020). Studies published until today showed viral RNA, but no infectious virus in semen (Li 2020) and viral RNA in vaginal fluid on only one occasion (Scorzolini 2020, Qiu L 2020). In a small study from Orléans, France, there was no transmission among discordant partners among five couples who continued sex while one partner was in the period of infectiousness (Prazuck 2020). Human corpses A recent stuy found that nasopharyngeal viral RNA stability in 79 corpses showed no time-dependent decrease. Maintained infectivity was supported by virus isolation up to 35 hours post-mortem (Heinrich 2020). There was no correlation between the post-mortem interval (time of death until cooling at 4°C; median 17,8 hours) and the viral RNA loads of corpses. According to the authors, their data indicate potentially high infectivity of human corpses, requiring careful and conscious handling.
Transmission Event Transmission of a virus from one person to another depends on four variables: 1. The nature of the virus; 2. The nature of the transmitter; 3. The nature of the transmittee (the person who will become infected); 4. The transmission setting.
Virus In order to stay in the evolutionary game, all viruses have to overcome a series of challenges. They must attach to cells; fuse with their membranes; release their nucleic acid into the cell; manage to make copies of themselves; and have the copies exit the cell to infect other cells. In addition, respiratory viruses must make their host cough and sneeze to get back into the environment again. Ideally, this happens before the hosts realize that they are sick. This is all the more amazing as SARS-CoV-2 is more like a piece of computer code than a living creature in sensu strictu (its 30,000 DNA base pairs are a mere 100,000th of the human genetic code). That doesn’t prevent the virus from being ferociously successful: • It attaches to the human angiotensin converting enzyme 2 (ACE2) receptor (Zhou 2020) which is present not only in nasopharyngeal and oropha-
Kamps – Hoffmann
