In an almost mathematical way since March 2020, each wave of COVID-19 has followed the same pattern: the number of infections escalates and, between one and two weeks later, hospitalizations in the ward, ICUs and, finally, deaths. The pandemic has been transformed since the arrival of vaccines, but the latest increase in transmission in Spain has not worked exactly like that. Although it had already been observed, it is in this seventh wave that it has been clearer that the contagion curve has pulled up from that of hospitalized patients, but not from the one that measures admissions to intensive care. ICUs have been spared the onslaught of the coronavirus.
The indicators and the way to measure and manage the pandemic have changed and it is no longer so easy to know what level of transmission of the virus there is, but once the curve of the sixth wave went down, there was an increase that the experts describe as "important". In fact, the accumulated incidence among those over 60, the only one that Health now gives, is 583 cases per 100,000 inhabitants. However, the number of ICU admissions has remained stable since they were freed from the effects of the wave in January and December: since last April 19, the occupancy rate has not risen above 4%.
The curve for intensive care remains flat, although that of less seriously hospitalized patients has risen. It is significant to compare it with previous rallies, for example the one that occurred last summer. With 15,000 cases reported in mid-July, two weeks later there were more than 1,600 people in the ICU. Now, with the same figure reported on May 10, 15 days later the number of patients in intensive care did not reach 400. And that taking into account that now the infections reported are those of people who were they test, only older and vulnerable.
But it is not just a matter of figures, those inside corroborate it: "During this last wave it has not been like on previous occasions, both in intensity in number and in severity of cases. At first we dragged patients from the previous one who had been hospitalized for a long time, but we have even come to be without any", says María Cruz Martín, head of the Intensive Medicine Service of the Torrejón de Ardoz Hospital. At the ICU of the Hospital del Sureste, in Madrid, no patients with coronavirus have arrived this time. "It has been very noticeable, the only one we have has been around for three months," confirms a service nurse.
For the professor at the University of Alcalá de Henares Pedro Gullón, "the fatality and hospitalization rate has been falling more and more throughout the pandemic", but in the last wave "a change in pattern has been more clearly observed ". The epidemiologist points out that the ICUs have not been filled because "the transmission has not been as high" as in the sixth, but above all because of the immunity that the population has already achieved: "Many of the booster doses were given in the recent months and there is also a great immunity acquired through the infection", which means that those who catch the virus again "have very little chance of it developing seriously".
There is a gap between the data for hospitalized patients and those admitted to the ICU. The former have risen with the escalation of cases. Gullón points to two possible reasons: on the one hand, that immunity "is stronger against the most severe, that is, death and ICU, a little worse for hospitalization and much worse for contagion." But, in addition, he believes that "not very serious" people may be admitted to the ward who in other waves of the pandemic, with the most saturated care level, "it is possible" that they would not have "fulfilled the hospitalization criteria."
The seventh wave "has caught us with good immunity and has fitted in well despite withdrawing all protection measures," believes Fernando García Artalejo, professor of Preventive Medicine and Public Health at the Autonomous University of Madrid, who still insists on that the pandemic is not over yet. As a differentiating factor compared to other waves, he points out that immunity "is even greater." And Javier Segura, president of the Madrid Public Health Association, agrees: "It is clear that ómicron has behaved differently from the previous variants. We have enough data to confirm a lower lethality and severity and that the vaccine has protected us less against contagion, but much in the face of gravity," he says.
Even so, the public health doctor believes that there is a lot of uncertainty and that right now the pandemic "is being less enlightened" due to changes in notifications. In fact, what has happened with the ICU admission curve does not crystallize in the same way in the death curve and Health continues to register figures of between 50, 60 or even 70 deaths per day. Gullón points out that it is possible that those who become more seriously ill are increasingly very vulnerable people, due to age or previous pathologies, "who do not go through the ICU." Segura points to another unknown, that of the excess mortality registered by the Carlos III Health Institute in May, of just over 3,300 people. "We have to wait for the figures to consolidate," he adds.
The experience shared by the hospitals confirms that at the same time the profile of the person who occupies the ICU currently also responds more and more to this pattern of very frail people. Martín, from the Torrejón de Ardoz Hospital, points to this, who in recent weeks has seen "in general" "older" patients, many of them vaccinated "and a high percentage, with immunosuppression and comorbidities." The Andalusian Society of Intensive Medicine and Coronary Units, which has reported "stability" in ICUs despite the increase in cases in the community, asserts this: they are people who "develop serious illness due to some degree of immunosuppression, either by other underlying pathologies or by treatments".
At this point, Segura believes that it would be useful to have specific data on the population's immunity, which is why he is betting that Health carry out a new seroprevalence study. "We do not know exactly what the level is, nor do we have information on cellular immunity," says the expert, for whom it is now interesting to know how the protection of the oldest, the first to be vaccinated, is. Precisely the Public Health Commission authorized this week a new booster dose for those over 80 years of age, who are expected to be vaccinated around the summer.
But in addition, experts differentiate between admissions and deaths from coronavirus and with coronavirus. It's the so-called "incidental" COVID, a phenomenon that was already seen in the sixth wave but that has worsened in this one and that implies that many of the patients admitted are not due to a serious illness derived from the virus, but rather respond to other factors but are also infected. There are, experts point out, many of these cases in which COVID can precipitate death, but they are usually people who were already very vulnerable.
Currently, Health does not break down the data in these groups, although, as confirmed by the department led by Carolina Darias a few weeks ago, it negotiates with the communities with this objective in order to give a more reliable image of the situation. “We have admitted patients for other critical pathologies that have been positive for COVID during screening and patients with other types of respiratory infections such as pneumonia due to the flu and pneumococcus with a positive PCR,” Martín exemplifies. A profile "completely different in clinical management", but that does require maintaining double circuits and "extreme precautionary measures" because "although the pictures are much milder", the pandemic, says the doctor, "should make us remain alert ".