The coronavirus variant of concern first discovered in India, known as Delta, is more likely to lead to hospitalisations that the Alpha variant first detected in Kent, data suggests, raising further concerns about its spread across the UK.
The Delta variant, also known as B.1.617.2, is the dominant variant in the UK – accounting for up to 75% of new coronavirus cases. It is believed to be more transmissible that the Alpha variant, and somewhat more resistant to Covid vaccines, particularly after just one dose.
Now a new report from Public Health England has not only revealed that confirmed cases of the variant in the UK have risen to 12,431 up from 6,959 the week before, but that it appears to be linked to an increased risk of hospitalisation compared with Alpha variant.
An analysis of 38,805 sequenced cases in England revealed that the Delta variant was associated with a 2.61 fold higher risk of hospitalisation within 14 days of specimen date compared with the Alpha variant. There was a 1.67 times higher risk of A&E care within 14 days. These figures take into account factors such as age, sex, ethnicity, area of residence and vaccination status .
Data from Scotland supported the findings, also pointing to a more than twofold higher risk of hospitalisation for those infected with the Delta variant compared with the Alpha variant.
“Confirmatory analyses are required to confirm the magnitude of the change in risk and to explore the link to vaccination in more detail,” the document states.
Prof Adam Finn, of the University of Bristol and a member of the Joint Committee on Vaccination and Immunisation said: “Although only a small number of cases end up in hospital, the proportion is about twice as high for Delta cases than Alpha cases in both England and Scotland.” he said. “The number of cases is still small, but if this trend continues and case numbers continue to rise quickly, that would point to a larger number of people being seriously affected as this variant continues to replace the alpha variant over coming weeks.”
Meaghan Kall, an epidemiologist at PHE tweeted that the growth rate for the Delta variant remains similar to the week before, and that its prevalence is rising in all regions of the UK.
“One shining light however is that vaccination still appears to be making an impact on spread,” she said, noting 73% of Delta cases are in unvaccinated people and only 3.7% Delta cases are in people who’ve had both doses, while only 5% of people hospitalised with this variant have had both jabs.
Dr Jenny Harries, chief executive, UK Health Security Agency, stressed the importance of Covid jabs. “If you are eligible and have not already done so, please come forward to be vaccinated and make sure you get your second jab. It will save lives,” she said.
The data comes as overall Covid cases in the UK continue to rise: on Thursday 4,330 new cases were reported, up from 3,165 the day before – a 37% rise.
Hospitalisations are also showing signs of an uptick in some parts of the country, highlighting that while the link between infections and severe disease has been weakened by the vaccination programme it has not been severed.
Prof Christina Pagel, director of UCL’s Clinical Operational Research Unit, said the new PHE report is concerning. “Every technical report seems to bring worse news. Added to increased transmissibility and some vaccine escape, we now have evidence that your chance of being hospitalised might be twice as high with the Delta variant than with the Alpha variant,” she said. “This makes it harder for vaccines to weaken the link between cases and hospitalisations.”
Prof Danny Altmann at Imperial College, London, agreed.
“This just adds to our ongoing concerns about the currently growing impact of the Delta variant. We knew it was more transmissible than our previously most concerning alpha variant and has rapidly been replacing it as the dominant strain. We also know that it has more profound immune evasion and poses an enhanced threat particularly to all who have so far received no vaccine or only one dose. To this we now add a further concern that those infected may have a raised chance of progressing to hospitalisation,” he said. “This is not where we wanted to be.”
Deenan Pillay, professor of virology at UCL and member of the Independent Sage group of experts, suggested the data threw further doubt on the easing of restrictions later this month.
“These are the sorts of data which make it more difficult to carry on with the roadmap as planned. This is the first time we’ve had a hint that the variant is associated with a greater risk of hospitalisation” he said.
“If a virus is more transmissible, a key driver can be a higher amount of viral replication and what goes along with that is more severe disease. That’s still to be confirmed, but it may be one explanation for what we are seeing.”
Pillay added that it is important that rules are adhered to despite the feeling that we are coming out of lockdown.
“There should be no laxity of protective measures like social distancing and the rest of it. Infections are rising and it’s essential people know the risks,” he said.