In a study from Massachusetts General Hospital, scientists examined the severity of the SARS-CoV-2 omicron BA.2 subvariant (the strain making a re-emergence this fall).
They found that the BA.2 subvariant is less severe than the previous delta variant and less severe to an even greater extent than the original omicron variant.
This pattern revealed in study suggests that the severity of SARS-Cov-2 may be diminishing.
In the study, the team aimed to provide an accurate assessment of the severity of SARS-Cov-2 variants above and beyond previous studies.
They used a method called entropy balancing to account for potential confounding factors such as prior infections, vaccinations, treatments, and comorbidities.
The team applied this method to data leveraged from the Mass General Brigham’s electronic health record system that’s linked to a COVID-19 vaccine registry.
They found among 102,315 confirmed COVID-19 cases from March 3, 2020 to June 20, 2022, there were 20,770 labeled as delta variants, 52,605 labeled as omicron B.1.1.529 variants (the original omicron variant), and 28,940 labeled as omicron BA.2 subvariants.
Mortality rates were 0.7% for delta, 0.4% for the original omicron variant, and 0.3% for omicron BA.2.
After adjustments, the odds of death were more than 2-times higher for the delta and the original omicron variant compared with omicron BA.2.
Patients with delta and original omicron variants were also more likely to need hospitalizations, invasive ventilation, and intensive care admissions.
The team says while the SARS-CoV-2 virus always has the potential to mutate to a more deadly form, when you look at the recent trajectory of delta, omicron BA.1, to omicron BA.2, the virus seems to be getting intrinsically less severe. Hopefully this trend will continue.
If you care about COVID, please read studies about how vitamin B may help fight COVID-19, and scientists find the cause of ‘brain fog’ in long COVID.
The study was conducted by Zachary Strasser et al and published in the JAMA Network Open.
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