SARS-CoV-2 Omicron BA.2 much less serious than Delta and authentic Omicron

In a up to date JAMA Community Open find out about, researchers estimate the severity of an infection with the serious acute breathing syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 subvariant in comparison to that brought about via the Delta and Omicron variants.

Learn about: Estimates of SARS-CoV-2 Omicron BA.2 Subvariant Severity in New England. Symbol Credit score: CI Pictures /


The SARS-CoV-2 Omicron (B.1.1.529) variant has been reported to be extra contagious however steadily, much less destructive than earlier variants in a lot of international locations, together with Canada, England, and Scotland.

Extra not too long ago, a number of Omicron subvariants have turn into dominant circulating traces during the arena, thus making it tough to resolve the severity of infections with those new subvariants. As well as, cohort research that experience sought to measure the Omicron BA.2 lineage severity have proven inconsistent effects, thus necessitating additional analysis.

In regards to the find out about

Within the provide find out about, researchers believe a number of confounding components, together with the adjusted dangers of loss of life, hospitalization, admission to an extensive care unit (ICU), and invasive air flow to check the severity of infections between SARS-CoV-2 Omicron BA.2, Delta, and Omicron variants.

Coronavirus illness 2019 (COVID-19) circumstances in adults and kids had been known between March 3, 2020, and Might 21, 2022. Eligible members both had a good polymerase chain response (PCR) take a look at or the digital well being file (EHR) had flagged them with a verified or suspected COVID-19 standing. When the illness used to be came upon, circumstances had been labeled into considered one of 3 teams: Delta, Omicron, or Omicron subvariant-infected.

Through examining the dominance of variants on residual diagnostic exams, duration limitations had been known. Delta circumstances happened between June 27, 2021, and December 5, 2021. Omicron circumstances had been known between December 26, 2021, and February 21, 2022. The Omicron BA.2 subvariant used to be assigned to any case between March 21, 2022, and Might 21, 2022.

The incident date of the an infection used to be the primary certain PCR or flag akin to a affected person. A affected person used to be regarded as newly contaminated with SARS-CoV-2 in the event that they reported every other certain PCR take a look at or new flag greater than 90 days after the incident date.

A minimal information ground requirement of a minimum of two analysis information six months aside within the 3 years ahead of the COVID-19 analysis used to be important to postulate enough data associated with a affected person to evaluate their comorbidity historical past and file their results. As well as, every affected person’s vaccination standing used to be divided into considered one of 4 classes 21 days previous to the affected person’s COVID-19 incident date, which integrated unvaccinated, the primary dose simplest, absolutely vaccinated, or absolutely vaccinated with a booster vaccine dose.

In-hospital mortality inside 30 days since COVID-19 analysis used to be the main result. Hospitalization, invasive air flow, and ICU hospitalizations had been regarded as secondary results. The affected person used to be labeled as having secondary results if those occasions happened inside 30 days of the COVID-19 incident date.

Learn about findings

The SARS-CoV-2 Delta, Omicron, and Omicron BA.2 traces had been assigned to twenty,770, 52,605, and 28,940 circumstances, respectively.

Each and every workforce’s demographics differed quite from the others. For instance, the Omicron variant had the bottom share of fellows who examined certain for SARS-CoV-2, whilst the Delta variant had probably the most important share. As well as, Omicron subvariant sufferers had been quite older, with a median age of 49.5 years.

All 3 populations contaminated via the 3 assessed variants reported an identical comorbidities. Significantly, an important choice of circumstances involving folks affected by power pulmonary illness, together with 4,529, 2,829, and seven,877 sufferers from the Omicron BA.2, Delta, and Omicron cohorts, respectively.

The Delta variant used to be related to 148 documented fatalities inside 30 days after an infection, while the Omicron and Omicron BA.2 variants had been related to 203 and 76 recorded deaths, respectively. This accounted for 0.7% of the Omicron BA.2 subvariant circumstances, 0.4% of the Omicron circumstances, and nil.3% of the known Delta infections.

After using entropy balancing to account for components like intercourse, gender, race and ethnicity, comorbidities, vaccination standing, remedies, and prior an infection, Delta mortality used to be upper than Omicron subvariant mortality, whilst Omicron variant mortality used to be upper than Omicron subvariant mortality.

After adjusting for covariates, the Omicron BA.2 subvariant used to be related to a considerably decrease chance of hospitalization than Delta. Then again, the Omicron variant used to be much more likely than the subvariant to motive hospitalization.

ICU admission used to be much more likely for Delta than Omicron subvariant infections. In a similar way, Omicron variant infections had been much more likely to lead to ICU admission than the ones because of the subvariant. 


The find out about findings confirmed that the SARS-CoV-2 Omicron BA.2 subvariant used to be a lot much less serious than the Delta and Omicron variants after bearing in mind many confounding variables related to SARS-CoV-2 results. After accounting for a number of variables, comparable to drugs, vaccines, and prior infections, the severity profile of SARS-CoV-2, about those novel variants, seems to be lowering.

Magazine reference:

  • Strasser, Z. H., Greifer, N., Hadavand, A., et al. (2022). Estimates of SARS-CoV-2 Omicron BA.2 Subvariant Severity in New England. JAMA Community Open 5(10):e2238354. doi:10.1001/jamanetworkopen.2022.38354

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