Another incentive for those who still hesitate to get vaccinated?
A large British study published this Saturday in The Lancet Infectious Diseases strongly suggests that people infected with the Delta variant, now hegemonic in France and in many countries, are twice as likely to be hospitalized as those infected with the variant. Alpha, majority until mid-spring.
This observation is especially true for the unvaccinated, the others being a priori very protected against the serious forms.
Read alsoCovid-19: why the Delta variant is suspected of causing more serious forms
The authors, most often members of Public Health England or researchers in British universities, analyzed the evolution of 43,338 cases tested positive between March 29 and May 23.
8682 had been contaminated with the Delta variant and 34,656 with the Alpha variant, according to the sequencing data.
The former were slightly younger than the latter (median age of 29 versus 31).
After adjusting the data for age, ethnicity, and vaccination status (among others), the risk of being hospitalized was 2.26 times greater with Delta variant infection than with the variant. Alpha (with a margin of error).
If we also take into account patients who simply went to the emergency room without necessarily being hospitalized, the risk is 1.45 times higher.
Results:
Adjusted analysis (for age, date, ethnicity, area, IMD, vax status and travel abroad) found
- Admission: Hazard Ratio 2.26 (1.32–3.89)
- A&E attendance OR admission: HR 1.45 (1.08-1.95) pic.twitter .com / oSLcbtlZvi
- Meaghan Kall (@kallmemeg) August 27, 2021
However, several biases can impact these results.
Hospitalizations unrelated to Covid may have been taken into account in error, which could lead to an underestimation of the risk of severe form in the event of infection with the Delta variant.
Conversely, if certain characteristics such as comorbidities were not analyzed, the results obtained could be slightly overestimated.
The “worst” epidemic wave averted?
It is interesting to note that these ratios are similar if we look at the subgroup of only unvaccinated within the sample (risk respectively 2.32 and 1.43 times higher). As for the vaccinated (with at least one dose) and hospitalized, their number "is too low to determine whether the risk [of hospitalization] was higher or similar for patients infected with the Delta variant compared to those with the Alpha variant. », Write the authors. Indeed, vaccines always protect very strongly against hospitalizations and severe forms with an effectiveness of about 90%, have shown many studies. Suddenly, it is difficult to say if there is a relatively greater risk with one variant compared to another.
The Delta variant would therefore not only be more contagious than Alpha, but also more serious in the sense that it would increase the risk of being hospitalized. Previous studies carried out in Scotland, Canada or Singapore had already suggested such a phenomenon, but they were often only at the pre-publication stage. "To our knowledge, this study is the largest assessment of the risk of hospitalization for the Delta variant using cases confirmed by whole genome sequencing, providing significant evidence of an increased risk compared to the Alpha variant," write the authors of this new work.
"Our analysis shows that if the vaccine was not available, an epidemic due to the Delta variant would place a greater burden on the health system than if it were caused by the Alpha variant," concluded one of the experts. between them, Anne Presanis. Thursday, Olivier Véran had also indicated that this epidemic wave would probably have been "the worst" if there had not been the vaccination.
