The population in Mexico, misinformed, has ignored for multiple reasons, the measures established by the Ministry of Health and is convinced that the pandemic has reduced its danger. I don’t think this is happening. Epidemic curves are relatively predictable with a progressive period of rise, a maximum peak with or without a plateau, and a slower decline than the rise curve.
Most people get it in their own home. The reason is simple, if a member of that family nucleus is infected, its presence and constant contact with the members of the same household, results in contagion.
First, to be infected, there must be exposure to a sufficient amount of the virus. Based on infections with other coronaviruses and influenza viruses that have been studied over the past decades, it appears that small amounts of the virus may be contaminating.
Some experts believe that just being exposed to 1,000 SARS-CoV-2 particles is enough to spread it. For practical purposes we can take this figure as the magic number to explain how the contagion of the virus to which you can be exposed can occur when receiving these particles in a breath or by rubbing your eyes with contaminated hands: if you are exposed to 100 particles each once you breathe in (people take 15-20 breaths / min on average), in 10 breaths you would inhale 1,000 virus particles and the same would happen with 10 rubs of the eyes. Each of these situations puts us at risk of acquiring an infection. Therefore, the use of face masks, frequent hand washing and avoiding rubbing the eyes are effective measures to avoid contagion.
A single cough releases 3,000 tiny droplets of viruses that travel at 80 km / hour into the environment. Most of these droplets are large and fall rapidly to the ground due to gravity, but the smaller ones remain in the air and travel rapidly through a room. A sneeze releases 30,000 drops that travel at 300 km / hour. Most droplets are small and travel long distances (easily across a room, subway car, passenger truck, or confined space).
If a person is infected, he can expel 200 million viral particles in a sneeze that are dispersed in the environment around the infected person. Imagine! A single breath through the mouth releases 50-5,000 droplets. Most of these droplets travel little and fall quickly to the floor, table, or nearby furniture. If you breathe through your nose, the amount of drops released is much less.
It is very important to note that exhalation is weak, so viral particles from the lower respiratory tract (trachea and bronchi) are not easily expelled. Talking releases 200 drops or virus / minute. That is, a face-to-face conversation for five minutes would be enough to obtain a sufficient dose of 1,000 particles to become contaminated.
Symptomatic patients are not the only ones capable of infecting. We know that about 44% of all infections or transmissions that occur in a community are from people without symptoms (asymptomatic). A presymptomatic person can spread the infection within five days before symptoms appear. It has been reported that the Achilles heel of contagion by Covid-19 resides in asymptomatic patients.
The amount of virus released by an infected person changes during the course of infection and is also different from person to person. Viral load progressively increases until the person becomes symptomatic. So the next time you feel like you can go out without a mask or to a meeting with your friends, think about it.