Later than usual, probably due to the persistence of high temperatures, the overall incidence of acute respiratory infections (ARI) is on the rise, a trend that, according to health authorities, indicates "the beginning of the epidemic waves of autumn-winter". While health centers are preparing for an increase in cases, only a quarter of the vulnerable population of Catalonia has been vaccinated against flu and covid, a significantly lower percentage than last year at this time .
In the last two weeks, the curve of the respiratory syncytial virus (RSV) and the flu has skyrocketed. The covid, on the other hand, maintains a more stable behavior, according to data from the Information System for the Surveillance of Infections in Catalonia (Sivic). "The RSV has been delayed by a couple of weeks, but we can already see that it is showing a change in trend that is beginning to resemble the epidemic phases," explains Jacobo Mendioroz, Deputy Director General of Surveillance and Response to Public Health Emergencies. What is normal, he points out, is that the rise of the respiratory syncytial virus is two weeks ahead of that of the flu, but this season they started the rise at the same time and have been climbing bravely for two weeks. The Department of Health calculates, in accordance with previous exercises, that the epidemic peak will take place in two or three weeks, but there are some unknowns.
Unknowns, for example, about the behavior of covid. There has never been a triple circulation, because some viruses impose themselves on others. At the height of covid, the flu practically disappeared from the scene for two seasons. "Right now it is difficult to interpret the behavior of covid, it has been oscillating for a few weeks, and even if it shows a slight rise, I would say it is stable", analyzes Mendioroz. "We will see if for the first time we will have a triple circulation of viruses, which I rather doubt, but it cannot be ruled out. We are in somewhat unknown territory". The evolution of this week and the next is being watched closely for the possibility of this triple wave that has never been seen before.
What would be the consequences? If covid and flu had the same intensity, the impact on the healthcare system would be the equivalent of twice a wave of flu, with a similar amount of income and morbidity, experts say.
One of the indicators of the beginning of this season's flu and RSV waves is the number of infections among people aged 15 to 44, the segment that has the most interaction and mobility. "After a couple of weeks it reaches the most vulnerable population", Mendioroz points out. For this reason, it is important that the population and the healthcare system are prepared: consultations and income will increase.
Of the 3,144 flu diagnoses made in Catalonia in week 46, from November 13 to 19 (2,354 the previous season), nearly half (1,438) correspond to patients aged 15 to 44. The percentage of positive samples has skyrocketed in the last two weeks.
Another of the unknowns of the season is the effect of vaccinations on children. For the first time, this autumn children between 6 and 59 months have begun to be immunized against the flu, which are added to people over 60 and to the population with risk diseases as vaccinable segments. However, the percentage of families who have opted for this protection is low (17% up to the age of four). The immunization of babies up to six months against the respiratory syncytial virus (RSV), one of the main causes of hospitalization in children under the age of five, due to the bronchiolitis and pneumonia it causes, also debuted this autumn.
Health centers are starting to notice bronchiolitis. In the last week analyzed, 680 cases were diagnosed in Catalonia - half corresponding to children under one year old - while two weeks ago there were 413. The curve is clearly pointing upwards, with a significant delay compared to previous campaign, when the peak was reached in week 47, the current one, with 1,872 diagnoses, and the curve started to go down.
Now that the indicators are starting to rise, which heralds epidemic phases, "it's a good time to start getting vaccinated against the flu and covid if you haven't already," says Mendioroz. "If any vulnerable person doubted it because it was hot, that has changed this week, and there is still time to acquire immunity for what is to come in about two weeks," he adds.
In fact, a relaxation is observed among groups susceptible to immunization: people over 60 and people with vulnerability factors. Only 26.62% of candidates have been immunized against the flu, the lowest percentage in recent years (last year at this time the rate was 33.22% and reached maximum, 43%, at the end of February). 55% of those over 80 are vaccinated.
With regard to covid, the vaccine coverage rate of the susceptible population remains at 22.59%, when a year ago it stood at 33.06% and reached the limit (47%) in February. Also in this case, the over 80 group is the most immunized (45%). Currently, there are 342 patients hospitalized for covid in Catalonia. It's the lowest number in the last four seasons in Week 46, but it's the highest in the last six weeks. On the other hand, there are ten people admitted to Catalan hospitals due to the coronavirus.
