July 26, 2021

19 – The data do not support the scaremongering generated by the Delta variant of the coronavirus


The United Kingdom has been for many the mirror in which to look at themselves in this latest phase of the pandemic. The severity of its restrictions and its agile vaccination rhythm caused the largest decrease in infections in the entire European continent in March. But focusing too much on another country and rushing to conclusions also carries its risks. This has happened with the Delta variant of SARS-CoV-2, originating from India and predominant in the British Isles, and its impact on the evolution of the health crisis.


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It is true that this lineage has caused an unexpected increase in cases in the UK. This June there have been figures that were not seen since March, with up to 11,000 positives a day after hitting the ground in May with less than 3,000. This has forced the Government of Boris Johnson to delay the de-escalation until July 19 – promised for June 21 – while that rising curve has been growing and going viral. But to what extent is it serious and can it concern other neighboring countries such as Spain?

Assuming that no increase in transmission is trivial, the most important thing is to observe its impact on healthcare pressure. The Delta variant has been shown to be 64% more contagious than the British (or Alpha) variant and already accounts for 99% of the cases identified in the United Kingdom. That would explain the rise in infections, but it is not the only thing. Delta has not had a commensurate impact on hospitalizations or deaths, as some rumors suggest.

The devastation has been announced with the arrival of all the variants – British, South African, Brazilian and Indian – and it has not arrived with any of them.

Rafael Toledo
– Professor of Immunoparasitology at the University of Valencia

The British health system has registered in the last 24 hours more than 15,000 cases and 204 new admissions. But just a month ago, when the peak began, there were 3,300 cases and 134 hospitalizations in one day. That is, a month ago new hospitalizations represented 4% of newly diagnosed cases, and now 1.36%. The death toll from COVID-19, meanwhile, also remains stable. But this could change, since fatality is a lagging indicator.

“It must be taken into account that there is always a gap between infections, income and deaths,” recalls Rafael Toledo, professor of Immunoparasitology at the University of Valencia. With caution ahead, the expert goes to the latest COVID report from the British system, which shows that “deaths are much lower than those produced by the Alpha variant.” From February 1 to June 14, of the 1,700 deaths recorded in the UK, 1,614 were linked to the Alpha variant and 73 to the Delta.

Even so, Toledo prefers to take the example of Scotland, “where infections have been rising for six weeks, and there has been no impact on hospitals.” “The evolutionary trend is that the most transmissible, but less pathogenic variants predominate; that is, those that cause less serious diseases,” he reassures. Regarding current scaremongering, the parasitologist recalls that it has previously occurred with all the variants prior to this –Alpha, Beta or Gamma–. “The devastation was announced with all of them and in no case has it come.”

In addition, the vaccines work against the Delta variant. The latest data published by the Government of Boris Johnson reveal that there are reasons for optimism. The first study carried out by the British Public Health Agency (PHE, Public Health England) showed that the effectiveness was reduced to 31% with the first Pfizer or AstraZeneca vaccine, while against the Alpha variant the protection with a single dose is of the 49%. With the full regimen, results are improved: 88% protection against symptomatic disease caused by Alpha and 80% by Delta. However, other research aimed at measuring its impact on healthcare pressure yielded new and encouraging percentages.

Hospitalizations for the Delta variant were reduced 94% with the first dose of Pfizer and 71% with the first dose of AstraZeneca. With both doses, 96% and 92%. Another study from the Scottish health service, published in The Lancet, shows that the risk of admission increases with respect to the Alpha mutation, but mostly affects the young population that has not yet been vaccinated. “It is extremely encouraging to see vaccines break the link between hospitalizations and the Delta variant,” stated UK Secretary of State for Vaccination Nadhim Zahawi.

In fact, if the age pyramid of those infected by this mutation is observed, most of them occupy the youngest age ranges, especially between 20 and 29 years. It is a less vulnerable group, but more exposed to the virus due to its social culture, its high mobility and that in many cases it has not yet received the vaccine (or at least not the full regimen). All of this, inevitably, is going to have an effect on the contagion curve.



“When the incidence is very low, the rises are more abrupt. It is easier to double an AI of 30 than one of 150. The important thing is that in England, the rise in the curve of hospitalized and deceased is very slight. Let’s see here, we would not call it a wave “, says Javier Álvarez, advisor to the Asturian Ministry of Health and scientific disseminator.

In fact, following the theory of the ecological niche, the Delta will predominate in a few weeks also in Spain. “What these variants do is compete with each other and select the best one. That is, the one that is transmitted the most,” explains Roger Paredes, clinical virologist and researcher at the Germans Trias i Pujol Hospital, in Badalona. “That lineages are replaced is something normal that happens with any virus, and after Delta, another will come,” adds Rafael Toledo. Assuming their predominance, the important thing is to know how they will affect the healthcare data.

What can we expect in Spain?

After two consecutive days with the incidence in slight increase, it is worth wondering if a future similar to that of the United Kingdom awaits Spain. The answer of the experts is that no. “The incidence no longer makes any sense, but you have to look at the care indicators and those of the deceased”, recommends Javier Álvarez. It must also be taken into account that “we have greatly increased mobility, even more than a year ago, when we were coming out of the state of alarm with leaden feet. This is going to be associated with more cases among young people, who are it is unvaccinated and the one that moves the most, but not necessarily to a new variant “, explains the popularizer.

The Delta is not even classified as a “worrying variant” by the Ministry of Health, but rather “of interest”, since it has been detected in 1% of the sequenced cases.

On the other hand, the Delta is not even classified as a “worrying variant” by the Ministry of Health, but “of interest”, since it has been detected in 1% of sequenced cases in Spain. And even if these increase, the pattern of hospitalizations and deaths may be different and more encouraging than that of the United Kingdom. The reason is simple: the vaccination strategy is different. “There they increased vaccination coverage by putting a first dose and lengthening the second. That is why there is a very high level of vaccination among the population, but almost all (around 80%) with first doses,” explains the Valencian parasitologist. On the contrary, the priority here has been to complete the pattern in the most vulnerable, a strategy supported by science.

What both experts agree on is that “you cannot legislate based on incidents and infections, because luckily they are not translating into healthcare pressure or serious cases,” argues Toledo. “What you have to do is manage the expectations, “recommends Álvarez.” Many people thought that with vaccination the disease was completely eliminated, but we will continue to have infections every day between now and December, “he bet.

Although the cumulative incidence has risen slightly to 93 cases per 100,000 inhabitants, hospital beds are 2% occupied and ICU beds 7%. “We have the same control of transmission as a year ago, but with much less damage both at the healthcare and economic level,” acknowledges the Asturian advisor. “I do not see the need to approach the pandemic in a different way, especially due to the social cost that it could have and that it is having,” concludes Toledo.

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