The Delta variant is the fastest, fittest and most formidable version of the coronavirus that causes COVID-19 the world has encountered, and it is upending assumptions about the disease even as nations loosen restrictions and open their economies, according to virologists and epidemiologists.
Vaccine protection remains very strong against severe disease and hospitalizations caused by any version of the coronavirus, and those most at risk are still the unvaccinated, according to interviews with 10 leading COVID-19 experts.
But the evidence is mounting that the Delta variant, first identified in India, is capable of infecting fully vaccinated people at a greater rate than previous versions, and concerns have been raised that they may even spread the virus, these experts said.
As a result, targeted use of masks, social distancing and other measures may again be needed even in countries with broad vaccination campaigns, several of them said.
Israel recently reinstated mask-wearing requirements indoors and requires travelers to quarantine upon arrival.
U.S. officials are considering whether to revise mask guidance for the vaccinated. Los Angeles County, the most populous in the United States, is again requiring masks even among the vaccinated in indoor public spaces.
Even in Canada, where hospitalizations and COVID-19 cases continue to decline, national data from the Public Health Agency of Canada warns the Delta variant stands a chance of unravelling some of that progress. The data suggests that, despite ground gained on COVID-19 nationally, the Delta variant may result in “greater than previously expected resurgence this fall and winter.”
“The biggest risk to the world at the moment is simply Delta,” said microbiologist Sharon Peacock, who runs Britain’s efforts to sequence the genomes of coronavirus variants, calling it the “fittest and fastest variant yet.”
Viruses constantly evolve through mutation, with new variants arising. Sometimes these are more dangerous than the original.
The major worry about the Delta variant is not that it makes people sicker, but that it spreads far more easily from person to person, increasing infections and hospitalizations among the unvaccinated.
Public Health England said on Friday that of a total of 3,692 people hospitalized in Britain with the Delta variant, 58.3 per cent were unvaccinated and 22.8 per cent were fully vaccinated.
In Canada, though COVID-19 cases are declining, Variants of Concern represent the majority of reported COVID-19 cases — approximately 70 per cent. For the week of June 20, 2021, cases of the Delta variant sat at 39 per cent, while Alpha cases sat around 38 per cent — the first time the two variant cases were reported in similar proportions.
In Singapore, where Delta is the most common variant, government officials reported on Friday that three-quarters of its coronavirus cases occurred among vaccinated individuals, though none were severely ill.
Israeli health officials have said 60 per cent of current hospitalized COVID-19 cases are in vaccinated people. Most of them are age 60 or older and often have underlying health problems.