Why Is Covid19 So Contagious?
In about two months, Covid19 has become a pandemic. The alert is not so much for its dangerousness as for its rapid spread, which puts health systems in check.
According to the WHO, Covid-19 (Coronavirus disease 2019) is more serious than the flu, mainly because no one has immunity. In addition, the contagion capacity is greater. That is mostly aerial, through droplets of saliva.
In the cases of MERS, SARS or influenza A, as we have seen from the WHO figures mentioned, the mortality was very high (up to 40%), but the contagiousness was rather reduced if we compare it with the normal virus flu or Covid-19.
On this occasion, it seems that we are faced with a very worrisome virus because it is highly contagious, which means that the affected population is much larger and that, therefore, the final death figures are more.
It doesn’t just hide in saliva
We will know if we are infected by a genetic detection of the virus in body fluids, generally in saliva, but also in feces and sometimes other fluids. In the acute process of the disease, in 80% of patients the virus is detected in saliva.
The proportion decreases in recovery (up to 30%) to possibly disappear. It is worrisome, however, that while in saliva it decreases, in the following days it increases in feces, constituting a potential risk of fecal / oral contamination (the contamination that possibly occurred in the “case zero” from an animal to a human being ).
It is not clear if there are false negatives, which is possible in any screening test, or if there are asymptomatic carriers, as in other types of flu; that is, people who can infect others without having the symptoms of the flu, or who, after having passed it, continue to present the virus. These data will become clearer in the near future, although the general opinion as this article is being written is that they are not the main source of contagion.
We have no immunity against it
Every day new information about SARS-CoV-2 comes out, sometimes denying the previous one. But one of the things that seems plausible is that, like previous viruses, it is a zoonosis. That is, a passage of the virus from one animal species to another. This in principle makes it more dangerous for humans, since we do not have a specific immunity against it or similar organisms.
It is, therefore, a new virus for the human species.
As in other cases, it is supposed to have occurred with the consumption of wild meat: possibly a bat – a natural reservoir of coronavirus – infected an animal that was a bridge with humans. And it is very likely that the “zero case” of the infection occurred in the Wuhan market, with the pangolin as the main suspect.
There is no treatment
Specific treatments are being made with antiviral drugs that have shown some efficacy in other viral diseases such as AIDS or SARS, among others. However, as in the case of the flu, there is still no treatment for this new viral disease.
The race to make a vaccine on time has started. In Europe, China, the United States and other countries it is already being developed, although it is under “construction”. Its efficacy has yet to be proven in experimental animals and in people. It is not about having a vaccine but that it is effective. In a hurry, it is possible that in the next flu campaign we could have a generic vaccine for the flu or specific for the coronavirus. Meanwhile, we will have to keep waiting.
What is a coronavirus?
It is a common and vulgar virus that, among other pathologies, can cause a simple cold. What is new about this type or species of coronavirus is that it had not been identified before in humans. Previously, we have had some similar outbreaks and other viruses.
- SARS (acronym for Severe Acute Respiratory Syndrome: Coronavirus that had an epidemic outbreak in 2003 that began in the Chinese city of Guandong and then spontaneously disappeared. It came from small mammals (possibly civets, which are eaten in China) and affected 8,500 people, with more than 800 deaths.
- MERS (acronym for Middle Eastern Respiratory Syndrome): Coronavirus endemic to dromedaries and camels in Arabia and East Africa, although it is thought to have been transmitted by bats. It first broke out in Lebanon in 2012 (2,000 cases with 712 deaths).
- Avian influenza or influenza A : Produced by various subtypes of the influenza virus (orthomyxovirus). It also produced an outbreak that started in Hong Kong, where people slept in close contact with chickens and birds. It is a zoonosis that affects birds and only sporadically affects people. There have been several outbreaks of avian flu (1997, 2003, 2013), the latest and best known is influenza A, in which it seems that the reservoir is waterfowl, in addition to poultry. The DNA of this virus is already included in the annual influenza vaccines because it has become one of those that participate in the influenza epidemics. According to the WHO, it has produced 861 cases with 455 deaths.
