The WHO has declared that the COVID19 disease is already a pandemic. Let us remember that this word means that there is a sustained, efficient and continuous transmission of the disease simultaneously in more than three different geographical regions. This is not synonymous with death: it does not refer to the lethality of a virus but to its transmissibility and geographical spread. No, we are not all going to die.
But why are the health authorities now insisting so much on these containment and isolation measures and why are they so necessary?
In an epidemic caused by an infectious agent, the number of cases increases progressively as time passes. To understand how an epidemic spreads in a population, three types of individuals must be taken into account: those who can contract the infection, those who are already infected, and those who have recovered and are no longer susceptible to becoming ill.
At first the number of susceptibles is high and the number of infected increases rapidly. As time goes by, the number of susceptibles decreases (because they have been cured, they have been immunized, we have vaccinated them or they have died). There are fewer people to infect and we are at the peak of the epidemic. This is called the density limit: the minimum number of individuals necessary to continue the disease . Once the pathogen has reached it, it can no longer be transmitted as effectively in the population and the number of cases decreases. So are the epidemic curves.
How fast the epidemic is going and how sharp that curve is depends on many factors. Among others, the transmissibility of the virus and whether the population is more or less susceptible to infection. The problem with this SARS-CoV-2 coronavirus is that it is very communicable and, being new, the population has not had previous contact with it, they have no immunity and, in principle, we are all susceptible to getting sick.
Knowing where we are on the epidemic curve is very difficult.
If the epidemic is going very fast and the curve is very sharp, one of the most serious problems is the collapse of the health system. It is not the same to have 10 cases in 10 days than 100 in a single day. Although 80% of cases of SARS-CoV-2 infection can be asymptomatic or mild, in 16% it can cause pneumonia and in 4% it can be fatal (provisional figures).
Pneumonia is not colds, they can be very serious and in many cases require going to a hospital and even being admitted. That is the big problem, that the capacity limit of the health system is exceeded and it collapses.
What remains above the capacity limit may be deaths.
That is why it is so important to stop the curve, the intervention measures. The goal is not for people not to get infected, this is probably already inevitable, but to delay and reduce the peak of the epidemic. For that, there are containment measures that are applied in the first days of the curve. It is when you have few and very localized foci, you know how they have been infected, you can diagnose and isolate the infected and follow up the people who have been in contact with that person and put them in quarantine.
Isolating the lights could slow down the curve
But sometimes that is not enough and the number of infected increases. As I said, knowing where we are on the epidemic curve is very difficult. That is when you must adopt more drastic measures, social quarantines, which must be as effective and sustainable over time and as least disruptive as possible.
What are those measurements? What real benefit will each have to stop the curve and what risk does it pose for the life of the citizen? That is a very difficult and complex decision. That is what the health authorities and governments are for, which are primarily responsible.
Therefore, we are now in the phase of braking the curve. Perhaps you are one of that 80% of healthy people who will become infected and will pass it in a more or less mild way. But your actions can help slow the curve or cause us to exceed the capacity of the system. We have to shield our hospitals and protect our toilets. We have to protect the weakest, those most susceptible to getting sick and even dying, not only from the virus but also from the health collapse. Older people with previous pathologies are the most vulnerable.
That is why all these measures that are being announced to us are so important. They are difficult, uncomfortable, they will affect us financially, but they are necessary. The best thing for a virus is a lot of people, close together and moving. The less we move and the further apart we are, the better.
10 basic tips to #BrakeTheCurve:
- Don’t panic, being alert is not an alarm.
- Wash your hands often and use good sneezing and coughing.
- Exercise social distancing: no kisses, hugs, handshakes. Look for alternatives.
- Do not go to crowded places: cultural, sporting and entertainment events.
- Avoid traveling if it is not absolutely essential. Reduce your trips on public transport.
- If you can, cut back on meetings and work from home.
- If you have any symptoms, stay home and use the phones indicated for them.
- Do not go to the hospital if it is not absolutely essential.
- Take care and protect especially the most vulnerable people, with previous pathologies and of legal age.
- Above all keep calm, there is also good news about the coronavirus.
This will pass, but we have to manage to stop the blow. Remember: you are the vaccine!
Ignacio López-Goñi, Professor of Microbiology, University of Navarra
This article was originally published on The Conversation. Read the original.
