Experts expect sixth wave in autumn

Santa Coloma de GramenetNeither health authorities nor epidemiologists hide their concern for September, when schools reopen and those who are still on holidays go back to work. With the recovery of the routine, which involves more mobility, a more intensive use of public transport and increased interaction in closed environments, the risk of contagion will also increase. And in Catalonia, which is slowly emerging from an unprecedented fifth wave due to the volume of accumulated infections (239,975 cases in just two months), the epidemiological situation is already serious: 9,000 positive cases are still being diagnosed every week and hospitals are treating 456 critically ill patients. With this explosive cocktail of high incidence and massive return to normality, the experts consulted by the ARA expect a new wave in autumn. Even the Catalan Health minister, Josep Maria Argimon, admitted on Tuesday that it a resurgence in Catalonia is "very likely".

If the forecasts are met, the autumn wave would be the sixth since March 2020. And it seems like it will not be the last in Catalonia. "It is certain that there will be new waves of covid, but if the delta variant is maintained, what will change will be the impact they have, basically thanks to vaccination", says the head of the service of preventive medicine and epidemiology of the Hospital Clínic, Antoni Trilla. The doctor and researcher at the University of Leicester Salvador Macip agrees with him, and believes it is "logical" to assume that there will be successive waves, as before. "However, this autumn will be different from last year and different measures will be needed to control the contagion curve", he explains. The two stress that the baseline number of diagnoses in September is likely to be very high, especially because of the outcome of the last few weeks and the increase in social contacts in August. The scenes of the last few nights in Barcelona and other cities, where street drinking parties have increased without any kind of protective measures, will have a full impact on the covid curve: "They are high-risk situations where more contagions will clearly appear that we can not yet see", warns Trilla.

This concern about the impact that September may have on the curve of the covid is not new. Around August last year, after a very harsh lockdown in spring and a summer full of outbreaks, there was also a sense of - justified - fear of a new wave: Catalonia experienced not one, but two before winter. According to experts, the difference between September 2020 and this year is the vaccination campaign: 70.9% of the population has begun to be vaccinated and 63.8% have the full vaccination schedule. "We have a high percentage of vaccinated people and now mortality will not be proportional to contagions. In each wave we will see a spike in hospitalisations and deaths, but not like last year", explains Macip.

This week, 151 people have lost their lives in Catalonia due to covid -an average of twenty per day-. Most of them were 80 years old or older and, most probably, many of them had been fully vaccinated for a long time. However, people over 65 usually have a weaker immune system and do not always respond to the stimuli of the vaccine. "Vaccines prevent especially severe forms of covid, but they do not protect at 100%. We know that without vaccines, with such a high number of infections, we would have seen again a dramatic mortality in old people's homes as in the first wave", says Trilla.

Vaccines and delta variant

The Catalan immunisation campaign has lost strength in recent weeks due to the summer holidays: if on 20 June 98,692 doses were inoculated, on 20 August half were administered, 50,631. This "transitory" stop generates some "concern" among authorities and experts. "But for the moment we have to be optimistic: if within two weeks the coverage does not increase or recover the weeks of August, then we will have to take more specific actions to recruit the undecided", says the doctor. Moreover, the fact that 7% of the population has received the first dose and has not yet received the second gives the authorities confidence. "In the face of the delta variant, it is important to have a large population with the full vaccine schedule", insists Trilla.

Vaccines are not the solution to the pandemic, but they are indispensable tools for controlling it. Although they also partly reduce the possibility of contagion, with previous variants the vaccines meant that those immunised were less involved in the chain of transmission. With the delta variant, this has changed radically: it is now more common for one infected person to also become infected and infect others. "There is still a decrease in infections thanks to the vaccines, but not as dramatically as before", admits the researcher. And even less so if those affected have only received the first dose, which is less effective against the mutation that originated in India.

Shielding schools

If the delta has decreased the protective effects of the vaccine (only in the infection, not in the protection against hospitalisation and death), this inevitably forces a modification of prevention measures. "We have already seen that those that worked in January were not useful in April and now they will not work in September. We have to adapt to the reality of each moment and it is clear that we have to make changes in the approach to hotspots of transmission," Macip points out. The doctor is referring mainly to work environments (encouraging teleworking or deploying hybrid models and staggering entrances) and public transport, where there will be crowds at peak times that may compromise epidemiological control.

However, if there is one point that worries experts, it is schools, which could become a hub for the spread of the virus, as it happened in the United Kingdom. There it was already seen that the delta circulated especially in schools because they were the places with less vaccinated population and, although the serious effects in children are minimal, they can transmit the virus at home. For this reason Minister Argimon has stated that he would like to reach 100% of first doses among the students over 12 years of age and 50% with a full vaccination schedule when the course begins, on 13 September. On Catalunya Ràdio radio station, Argimon has indicated that this implies around 300.000 people and that they could be vaccinated in a week.