When India was hit by a tsunami of new cases in the spring, the situation was too complex to blame the second wave of covid on the new variant found in the country. In the UK, that same variant, which we know today as Delta variant, was identified in April, as the British government proceeded to the first reopenings:
- how contagious is the Delta variant?
- how dangerous is it?
- how much does the first dose of a vaccine protect?
- and full immunization?
Today this version of the coronavirus is responsible for more than 90% of covid cases in the country, at the center of a third pandemic wave muffled – fortunately – by vaccines. But British scientists are certainly not watching the new outbreaks with their hands in their hands. Their valuable tracking work has allowed them to gather new information on the Delta variant, now present in 80 different countries.
Contagiousness and vaccine resistance. The Delta variant (B.1.617.2, initially called “Indian”) is thought to be over 60% more contagious than the Alpha variant (B.1.1.7, initially called “English”) which had previously established itself in UK. The increased transmissibility could explain the resurgence of infections in Nepal and some Southeast Asian countries. Delta also seems capable of at least partially evading the defenses developed thanks to vaccines, if nothing else in those who have had only one dose: A single injection of Pfizer or AstraZeneca vaccine reduces the risk of contracting symptomatic covid by 33% – while for the Alpha variant a single dose reduces the risk by 50%.
After the second dose, the effectiveness against the Delta variant increases to 60% in those vaccinated with AstraZeneca and 88% in those protected by Pfizer. In short, the protection offered decreases, but not so dramatically: it is therefore a priority to complete the vaccination cycle.
Severe forms and hospitalizations. According to a Scottish study, some preliminary data suggest that people infected with the Delta variant run a two times higher risk of hospitalization for covid, compared to those affected by the Alpha variant. However, there is still no certainty about the ability of this version of the coronavirus to cause a more serious disease.
Vaccines are certainly doing their job and warding off the most severe forms in those who are covered. The rush of new cases, which in England double every 11 days, is not accompanied by a proportional increase in hospital admissions. According to Public Health England, those who have received a dose of any vaccine run a 75% lower risk of hospitalization for covid than those who are not vaccinated, while in those who are protected with a double dose the risk of hospitalization falls by 94%.
The privilege of being vaccinated. And while Europe measures the ability of vaccines to moderate the impact of the Delta variant, in countries where vaccines have not yet arrived due to Western selfishness, a devastating impact is feared. In Africa, where most nations have less than 5% of the population vaccinated, vaccines will never arrive in time to counter the spread of the contagious Delta variant. Cases of the Delta variant have been reported in the Democratic Republic of the Congo after an outbreak in the capital Kinshasa, Malawi, Uganda.
In South Africa the Delta has been identified in commercial ports and among naval crews with frequent relations with India, but has not taken hold in the rest of the population. The country is in fact in the midst of a third wave of cases caused by the Beta variant (B.1.351, formerly known as “South African”) identified last year. The prevalence of another stronger variant has so far prevented the spread of the new one, a phenomenon that seems to be underway also in Brazil, where the Gamma variant is still widespread (P.1, “Brazilian”).
In the USA. The Delta variant is responsible for one in five cases of covid in the United States today, where its prevalence has doubled in the past two weeks. Here, with the number of vaccinated people falling and a vast disparity in the number of immunized people from one state to another, a “patchy” spread is expected, with outbreaks located mainly in localities with less than 30% of vaccinated population.