The rate of contagion r announces us from another possible wave

At this point of pandemic we are all related to certain terms and what they imply. Let's talk about the famous number R0 or Rt. The basic number of playback

The rate of contagion r announces us from another possible wave

At this point of pandemic we are all related to certain terms and what they imply. Let's talk about the famous number R0 or Rt. The basic number of playback (also reproduction number or contagion rate) tells us the average number of secondary cases that each infected subject may come to infect. When it is above 1 (for each infected person another is contagious) the disease is transmitted and below 1 the COVID is being controlled.

In this number they intervene, for good and evil, many factors, for example, human behavior, protection measures, immunity that are reached or the effect of vaccination. If we serve the data and the graphics, we can clearly see that effectively the increase in this number is usually the anteroom of an epidemic wave.

According to data from the Carlos III Health Institute, on March 10, 2020 we had an R of 2.64. It would probably be greater since, as other parameters in the first wave, it is less reliable because the measurements were not as accurate or test. That number gradually lowered and remained below 1 from the end of March and until mid-May, when he climbed slightly and descended until the end of June. On July 1, it was 1.18 and on July 7, R of that wave was reached, 1.32 (remember the first outbreaks of the temporary in Lleida and in other areas of Spain). We had a summer of outbreaks in which the R number remained above 1 and a second long wave in time, all the summer and autumn.

With an R of 1.26 on October 20 (the highest in that period) that second wave continued to be extended, whose peak in accumulated incidence (number of cases per 100,000 inhabitants in 14 days) was reached by 9 November. If we continue to observe the R, it came down below 1 and returned again on December 11 (1.09), which marked the beginning of the third wave that almost overlapped with the second in Spain. The R went up (1.23 on December 15) until reaching 1.32 on January 5. On January 27, the incidence peak of the third wave was reached: 899.93 (First the rate of contagion is seen, then cases).

The number R descended and returned to 1 March 13. On April 9 it reached 1.15 (the highest figure of the fourth wave) and on April 26, the incidence peak of the fourth wave (235.59) was reached. As we see, 15-20 days after reaching the maximum R of each wave is reached the peak of incidence of that wave. R returned again and maintained below 1 to 18 June (1.01), rose up to a maximum of 1.74 on July 1 and July 27, this time 26 days later, the peak of incidence of the Fifth Ola (701,92).

Until October 13, R remitted below 1. At present, Spain registers an R of 1.05, although this figure, like all during the pandemic, is variable according to the Autonomous Communities. 12 autonomies are above 1. Only La Rioja (0.86), Andalusia (0.94), Castilla-La Mancha (0.95), Catalonia (0.95) and Cantabria (0.99), in addition to The autonomous cities of Ceuta (0.59) and Melilla (0.57), are kept below 1. If we serve only to these figures, are we in the anteroom of a sixth wave?

"R helps us to see the speed of transmission, but we are also pending other tendencies. In Spain and in some communities it is uploading that number and we could think of that possibility, but there are other factors, other parameters such as traceability, the percentage of positive or hospital admissions that do not go on that line. Take only the number R does not give us a complete picture of what may be happening, we must be very prudent, "explains José Jonay Ojeda, spokesman for the Spanish Society of Public Health and Health Administration (SESPAS).

Ojeda adds that within the Public Health Commission, a job is pending: "The current traffic light does not contemplate the effect of vaccination. Therefore, this tool, and this I say it very carefully, could be overestimating the risk." In that sense, Sespas spokesman emphasizes that we are in "the second best scenario of the pandemic". "The first was in June last year, after leaving confinement, when we had the lowest incidence, at this time we are with the second lowest incidence of the pandemic, it is the perfect moment precisely to maintain that traceability of cases (detect them And follow them to break the transmission chain). And to that the greatest protection that vaccination has to be added ".

Without wanting to be agrolers, remember that in that best scenario of the pandemic last year the situation went hand in hand and we were not able to maintain traceability. And, after the first wave, the worst we have lived was the third, last winter. Could we live a sixth wave now that the cold arrives, although of less magnitude?

"There are two factors that play against us, clearly. On the one hand, the perception of risk. We have many months of pandemic, people are tired, the situation has improved a lot in recent months and with the desired of measures (aprote , Hospitality ...) People can interpret it as there are no longer contagion and that is a big risk. This perception of risk is a factor that we have not been able to measure throughout the pandemic, as a tool, "says Ojeda.

"The other factor against is the arrival of winter and that we make more life indoors, where we already know that the virus is transmitted much more, and several bridges arrive, we have already seen that when this happens people go to leisure mode and It relaxes. These factors could explain an increase in R, but we have to continue testing so that the cases are not escaped, especially since there are still unobscured groups, not because they have not necessarily wanted, and in certain population groups the effectiveness From the vaccines, he slows over time, hence the reinforcement doses. You have to be careful, "says Sespa spokesman.

Let's also remember that each variant has different contagiousness. Thus, while in the original strain of Coronavirus for each infected person, something more than two were infected, with Delta for each infected person, five, according to data from the US CDC (centers for control and disease prevention). The first cases of Delta Plus have been detected in Spain, could it influence an increase in the R number?

"Right now there are not many cases, this variant is being monitored that is starting to circulate. In the future it could be a variant that causes epidemic waves, if it were dominant I could explain the waves in other countries but it is difficult to know what role it plays, if It is because of that alone or by other factors such as the relaxation of measures or a lower vaccination rate, "says Ojeda, who reviews that health authorities should watch it and continue making adequate decisions according to epidemiological evolution, and citizens should remember that The pandemic has not finished yet. In that aspect, we must continue to fulfill the measures that have helped us, especially now that cold and indoors are coming: distance, mask and ventilation.

Updated Date: 30 October 2021, 09:58

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