Severity of the Omicron SARS‐CoV‐2 variant compared with the previous lineages: A systematic review

The Omicron variant was first detected in October 2021, which evolved from the original SARS‐CoV‐2 strain and was found to possess many mutations. Immune evasion was one of the notable consequences of these mutations. Despite Omicron exhibiting increased transmissibility, the rates of hospitalizatio...

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Published in:Journal of cellular and molecular medicine 2023-06, Vol.27 (11), p.1443-1464
Main Authors: Arabi, Maryam, Al‐Najjar, Yousef, Mhaimeed, Nada, Salameh, Mohammad A., Paul, Pradipta, AlAnni, Jamal, Abdelati, Ali A., Laswi, Ibrahim, Khanjar, Bushra, Al‐Ali, Dana, Elshafeey, Abdallah, Mhaimeed, Omar, Burney, Zain, D'Souza, Ashton, Sinha, Pratyaksha, Bhatti, Mohammad, Pillai, Krishnadev V., Homssi, Moayad, Bshesh, Khalifa, Yagan, Lina, Zakaria, Dalia
Format: Article
Language:English
Subjects:
Alpha
Asymptomatic
Beta
COVID-19
COVID-19 Vaccines
Databases, Factual
death
Delta
Female
Hematology
Hospitalization
Humans
ICU
Immune response (humoral)
Infant
Infant, Newborn
Infections
Mutation
Neonates
Omicron
Patient admissions
Pregnancy
Pregnancy Complications, Infectious
Review
SARS-CoV-2 - genetics
SARS‐CoV‐2
Severe acute respiratory syndrome coronavirus 2
severity
Systematic review
Ventilators
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Summary:The Omicron variant was first detected in October 2021, which evolved from the original SARS‐CoV‐2 strain and was found to possess many mutations. Immune evasion was one of the notable consequences of these mutations. Despite Omicron exhibiting increased transmissibility, the rates of hospitalizations and deaths among patients infected with this variant were substantially lower when compared to other strains. However, concluding that the Omicron variant is less severe than other variants of SARS‐CoV‐2 requires consideration of multiple factors, including the vaccination status of infected patients as well as any previous infections with other variants. This review compiled data about any reported indicators of severity in Omicron‐infected patients, including studies comparing Omicron with other variants while adjusting for confounders. A comprehensive search was conducted using different databases to target any studies about Omicron. In total, 62 studies met our inclusion criteria and were included in this study. Many studies reported a significantly reduced risk of hospitalization, ICU admission, need for oxygenation/ventilation, and death in Omicron‐infected patients compared to patients infected with other variants, such as Delta. Some studies, however, reported comparable severity in Omicron infected patients as to other variants emphasizing a substantial risk for severe illness. Furthermore, the COVID‐19 vaccines were less effective against Omicron relative to previous lineages, except after receiving the booster dose. One study recommended vaccination during pregnancy, which may help prevent future cases of severe SARS‐CoV‐2 pneumonia in neonates and young infants due to the transfer of humoral response from the mother.
ISSN:1582-1838
1582-4934
DOI:10.1111/jcmm.17747