Study Suggests Delta COVID-19 Variant Doubles Risk of Hospitalization

The COVID-19 Delta variant has a hospitalization rate about double that of the Alpha variant that spread throughout the United States, according to new research from Public Health Scotland and the Universities of Edinburgh and Strathclyde published on Monday by The Lancet.

“In summary, we show that the Delta VOC [Variant of Concern] in Scotland was found mainly in younger, more affluent groups,” the study reads in summary.

“Risk of COVID-19 hospital admission was approximately doubled in those with the Delta VOC when compared to the Alpha VOC, with risk of admission particularly increased in those with five or more relevant comorbidities. Both the Oxford–AstraZeneca and Pfizer–BioNTech COVID-19 vaccines were effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalisation in people with the Delta VOC, but these effects on infection appeared to be diminished when compared to those with the Alpha VOC.” 

The researchers note that they “had insufficient numbers of hospital admissions to compare between vaccines in this respect. The Oxford–AstraZeneca vaccine appeared less effective than the Pfizer–BioNTech vaccine in preventing SARS-CoV-2 infection in those with the Delta VOC. Given the observational nature of these data, estimates of vaccine effectiveness need to be interpreted with caution.”

Chris Robertson, professor of public health epidemiology at the University of Strathclyde, said during a news briefing on Monday that the Delta variant became the dominant strain in the country sometime around mid-May, and is responsible for 75% of all positive cases in Scotland.

“If you test positive, then two doses of the vaccine or one dose for 28 days roughly reduces your risk of being admitted to hospital by 70%,” Robertson told reporters, according to Reuters.

The Pfizer BioNTech Covid-19 vaccine, which was 92% effective against the Alpha Covid-19 variant, protected against infection from the Delta variant 79% of the time. The Oxford-AstraZeneca vaccine protected 60% against the Delta variant, compared to 73% for the Alpha variant.

“The Delta variant does increase the risk of hospitalization,” Jim McMenamin, Covid-19 National Incident Director for Public Health Scotland, said during a press conference according to Politico Europe. "However, what we are able to see from the information available to us is that our vaccines are still highly effective."

“The vaccines are the most important tool we have against Covid-19,” Mary Ramsay, Public Health England’s head of immunization, added in a statement. “It is absolutely vital to get both doses as soon as they are offered to you, to gain maximum protection against all existing and emerging variants.”

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