A new study of 40,000 Britons infected with Covid-19 shows that compared to the Alpha variant, the Delta variant doubles the risk of hospitalization. It is also 40 to 60% more transmissible.
- Compared to people infected with the Alpha variant, those affected by the Delta variant have a 2.6 times higher risk of being hospitalized.
- Among those infected, 74% were not vaccinated and 24% were partially vaccinated.
- Only 1.8% of Covid-19 cases had received both doses of the vaccine, which underlines the effectiveness of the vaccine in limiting severe forms of Covid-19.
People infected with the Delta variant of SARS-CoV-2 are at twice the risk of hospitalization than those infected with the Alpha variant. This is confirmed by a study of more than 40,000 cases that occurred in England between March 29 and May 23, 2021 and published in the journal The Lancet Infectious Diseases.
According to its authors, the risk of being hospitalized for emergency care or being admitted to hospital within 14 days of infection is also 1.5 times higher with the Delta variant than with the variant Alpha.
“This study confirms previous findings that people infected with the Delta variant are significantly more likely to require hospitalization than those infected with the Alpha variant, although most of the cases included in the analysis were unvaccinated. We already know that vaccination offers excellent protection against Delta and as this variant accounts for over 98% of Covid-19 cases in the UK it is vital that people who have not received two doses of the vaccine do so. as soon as possible”recalls Dr. Gavin Dabrera, consultant epidemiologist at the National Infection Service and lead author of the study.
A risk of hospitalization multiplied by 2.6
First reported in India in December 2020, the Delta variant is up to 50% more transmissible than the Alpha variant first identified in the UK, and is now the majority in all countries worldwide.
In the case of the current study, researchers analyzed healthcare data from 43,338 positive cases of Covid-19 in England between March 29 and May 23, 2021. Virus samples were collected and subjected to a whole genome sequencing to find out which variant had caused the infection.
During this period, 34,656 cases of the Alpha variant (80%) and 8,682 cases of the Delta variant (20%) were recorded. The proportion of contaminations with the Delta variant has gradually increased to represent 65% in mid-May 2021.
About one in 50 patients were hospitalized within 14 days of their first positive test. This represented 2.2% Alpha cases and 2.3% Delta cases. After taking into account factors known to affect susceptibility to serious illness from Covid-19, the researchers found that the risk of being hospitalized was increased 2.26 times with the Delta variant.
74% of people hospitalized were not vaccinated
However, the study demonstrates the effectiveness of vaccination to avoid developing a severe form of the disease and being hospitalized. In this study, only 1.8% of Covid-19 cases had received both doses of the vaccine. 74% of cases were unvaccinated and 24% were partially vaccinated.
“Our analysis highlights that in the absence of a vaccine, the risk of hospitalization is high and that the Delta variant will impose a greater burden on health care than the Alpha variant. Full vaccination is essential to reduce the risk of symptomatic infection with the Delta variant and, most importantly, to reduce the risk of serious illness and hospitalization”concludes Dr. Anne Presanis, one of the main authors of the study.
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