The Delta variant, first identified in India, is spreading rapidly in many parts of the world and is going to replace the Alfa variant, discovered in England.
been identified in at least 92 countries and in the United Kingdom it now accounts for almost all cases (99%).
In Italy the estimates range from 17 to 26% with the forecast of a rapid rise in these percentages.
Do you get infected after 5-10 seconds?
The most striking feature of the Delta is its great transmissibility: some calculations made mainly on data from the United Kingdom, suggest that the Delta is about 60% more transmissible than the Alpha variant, which in turn was 50% more transmissible than the strain we had in Europe last year.
In Australia, the announcement of the premier, Gladys Berejiklian, made a sensation, declaring that the cluster of Bondi (a beach near Sydney) originated from a frighteningly fleeting encounter between two unvaccinated people, and without a mask, for 5-10 seconds inside a shopping mall.
The deduction was made on the basis of some CCTV footage and after an investigation into the contacts of the Chief Health Officer state, Kerry Chant. Queensland Head of Healthcare Dr Jeannette Young said: At the start of this pandemic, I said 15 minutes of close contact was a time to watch out for. Now it seems like 5 to 10 seconds are worrying. The risk is much higher now compared to just a year ago.
Respiratory aerosols accumulate in the same way that cigarette smoke accumulates – he stressed and continued -. In an enclosed space where ventilation is inadequate the virus still in the air. So if you walk around that area and breathe that air, you could be infected.
When do you risk it?
At that time in Sydney, masks were not mandatory (not even indoors) and there is also to consider that less than 5% of the Australian population received both doses of the vaccine.
The estimate of 5-10 seconds – although coming from official sources, starting with the Queensland health officer – are an empirical deduction which must find confirmation e not based on any study.
for true thatthe virus travels through the air and can fill closed, poorly ventilated environments for hours after release from an infected subject.
If previously a risky contact was considered to be talking to someone indoors for more than 15 minutes, in the presence of a much more contagious virus this parameter of minutes can certainly go down, but we are not certain about this.
The most powerful weapons remain ventilation and mask – in addition, of course, to vaccines, which reduce the possibility of contagion by about 50%.
Delta, what we really know: transmissibility and symptoms
clear that Delta has a substantial transmission advantage: Patient Zero in the recent Sydney outbreak was a limo driver who caught the virus from a passenger.
He was not vaccinated, he wore a face mask, he was not tested regularly.
In New South Wales, of which Sydney is the capital, officials report one domestic transmission close to 100% compared to 25% of previous strains. More than five million people in and around Greater Sydney have now been stranded for a 14-day lockdown. From the most recent UK studies we know that Delta has an overall advantage on paper of 60-70% over Alpha. In a place like the UK where so many people are vaccinated or cured, this advantage is reduced to 30-40%but in Australia just under 5% of the fully vaccinated adult population, with 29% receiving only a first dose.
In addition to the estimate on the greater contagiousness, we know that the Delta variant causes slightly different symptoms: headache, sore throat, runny nose and fever.
The rarest cough is loss of smell not even listed in the top ten symptoms.
Thus the risk that younger people – who are already less likely to develop serious illnesses – may mistaking these symptoms for a bad cold and not getting tested.
Another detail of the Delta quite sure that it can be linked to a greater risk of hospitalization: according to a Scottish study published in The Lancet on June 14, the Delta variant associated with approximately twice as many hospitalizations as the Alpha variant.
What we don’t know
even a little more resistant to vaccines, especially after one dose: The UK National Health System (PHE) found that three weeks after a first dose, the vaccines provided 33% protection against symptomatic disease caused by the Delta variant, compared to around 50% protection for the Alpha variant , but the same vaccines after two doses are 96% effective against hospitalizations.
What we still don’t know to what the advantage in transmissibility is due, if a specific booster of vaccine against this variant will be needed e whether it is more or less lethal.
The latter point is the most difficult to measure, as there have not yet been enough deaths to systematically compare those associated with Delta and other variants, plus, those who received two doses of the vaccine in the UK tend to be older. and clinically more vulnerable and for this reason it can happen that they worsen even after complete vaccination. Finally, remember that, on average, there is a 3% of people on whom the vaccine has no effect. In fact, no vaccine is 100% effective.
Delta variant: insights
June 29, 2021 (change June 29, 2021 | 15:08)
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