The Delta coronavirus variant, first identified in India, carries about double the risk of hospitalization compared with the Alpha variant, first identified in the U.K., according to research from Scotland released today.
While vaccination is providing roughly 70 percent protection from hospitalization, it’s vital people receive their second dose, since protection shortly after the first dose is limited, the authors stressed.
The Delta variant has become dominant in Scotland since mid-May, and now accounts for around 75 percent of all positive cases, said Chris Robertson, professor of public health epidemiology at the University of Strathclyde, during a briefing. And more younger people are among those hospitalized.
The study is in line with Public Health England, which has said the Delta variant is more transmissible than Alpha and suggested it could cause more hospitalizations. But PHE has also called for more evidence.
The latest data comes ahead of the U.K. Prime Minister Boris Johnson’s announcement this evening on whether pandemic restrictions will be eased, with a delay most likely on the cards.
“The Delta variant does increase the risk of hospitalization,” said Jim McMenamin, COVID-19 National Incident Director for Public Health Scotland. “However, what we are able to see from the information available to us is that our vaccines are still highly effective.”
The BioNTech/Pfizer vaccine provided 79 percent protection against infection from the Delta variant, compared with 92 percent against the Alpha variant, at least two weeks after the second dose, the study found.
The Oxford/AstraZeneca vaccine, meanwhile, offered 60 percent protection against the Delta variant compared with 73 percent for the Alpha variant.
The researchers, from Universities of Edinburgh and Strathclyde and Public Health Scotland, said the different efficacy rates may reflect that is takes longer to develop immunity with the Oxford/AstraZeneca jab. But they also cautioned it’s not possible to directly compare the vaccines since they’ve been prioritized for different groups of people.
Across both vaccines, the data also showed a “worrying” slightly higher risk of hospitalization with the Delta variant than Alpha after two vaccine doses, noted Robertson.
The results from this analysis, published today as an externally peer-reviewed research letter in the Lancet, was based on community testing among 5.4 million people in Scotland from April 1 to June 6.
“There is much work that needs to be done to substantiate the information,” cautioned McMenamin. “But a full understanding of what those will mean … can only follow if we are able to combine the analysis that’s been done in other parts of the U.K. or internationally.”