• Amarildo Prendi

Vaccination Reduces Risk of Hospitalization From all SARS-CoV-2 Variants, Study Says

A team of scientists from the USA has recently examined the risk of hospitalization in patients infected with extra deadly variants of severe acute respiratory syndrome coronavirus two (SARS-CoV-2).



The findings reveal that patients infected with alpha, beta, gamma, and delta variants have a greater risk of hospitalization than those infected with the original viral strain that emerged in Wuhan, China, in late December 2019. The study is currently available on the medRxiv* preprint server while awaiting peer review.


A total of 23,170 cases with available viral genome sequencing data have been analyzed in the study. The sequencing analysis revealed that non-VOCs/VOIs have been dominantly circulating in Washington State at the beginning of the pandemic. However, by March 2021, the essential VOCs/VOIs gained dominance by replacing the previously circulating variants.


Among all VOC-infected COVID-19 cases, 38.4% were associated with the alpha variant, 1% with the beta variant, 8.8% with the gamma variant, and 8.7% with the delta variant. Among all VOI-infected cases, 16% were associated with the epsilon variant, and 3% have been with other examined VOIs. Apart from VOC/VOI cases, about 24% of enrolled cases were associated with the authentic SARS-CoV-2 strain. Regarding demographics, about 91% of enrolled instances were under the age of 60 years, and 94% were unvaccinated.


Risk of hospitalization

A total of 726 hospitalized cases were identified in the evaluation (3.1%). Among these cases, 247 were with alpha infection, 12 with beta infection, 127 with gamma infection, and 74 with delta infection. The highest risk of hospitalization was observed for gamma infections, followed by beta, delta, and alpha infections. Other examined variants did not exhibit any significant impact on the risk of hospitalization.


Changing proportion of infections due to variant lineages in Washington over study period. Variant fraction is calculated from a 21-day rolling average from our full sequenced dataset spanning from December 1, 2020 to June 30, 2021 and normalized to 100% to better observe changes in percentage of infections from variant lineages compared to total infections.

Changing proportion of infections due to variant lineages in Washington over study period. Variant fraction is calculated from a 21-day rolling average from our full sequenced dataset spanning from December 1, 2020 to June 30, 2021 and normalized to 100% to higher observe changes in proportion of infections from variant lineages compared to total infections.


Vaccination status and risk of hospitalization

A separate set of analyses was conducted in the study to compare the risk of hospitalization among variant-specific COVID-19 cases stratified by the vaccination status.


The analysis considering only unvaccinated cases revealed that in contrast to patients with original SARS-CoV-2 infections, the gamma-infected patients have the highest risk of hospitalization, accompanied by delta- and alpha-infected patients.


In contrast, no significant influence of VOCs on the risk of hospitalization was found in the analysis that considered only vaccinated cases. In a separate analysis considering all COVID-19 cases irrespective of viral variants, it was observed that vaccinated patients have a comparatively decrease risk of hospitalization than unvaccinated patients.


Relative Risk of Hospitalization by Variant Lineage. Risk of hospitalization is compared to individuals infected with an ancestral lineage. Error bars represent 95% CI. Estimates are adjusted for age, sex assigned at birth, and vaccination status.

Relative Risk of Hospitalization by Variant Lineage. Risk of hospitalization is compared to folks infected with an ancestral lineage. Error bars represent 95% CI. Estimates are adjusted for age, sex assigned at birth, and vaccination status.

Study significance

The study indicates that sufferers infected with SARS-CoV-2 VOCs have a higher risk of hospitalization. However, the risk can be decreased by COVID-19 vaccination. These findings highlight the need for hospital preparedness and mass vaccination in controlling COVID-19 associated morbidity and mortality.


Originally published: News Medical

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