Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2022 Apr 11;19(8):4586.
doi: 10.3390/ijerph19084586.

Is the SARS CoV-2 Omicron Variant Deadlier and More Transmissible Than Delta Variant?

Bao V Duong  1 , Puchanee Larpruenrudee  1 , Tianxin Fang  1 , Sheikh I Hossain  2 , Suvash C Saha  1 , Yuantong Gu  3 , Mohammad S Islam  1
Affiliations
Review

Is the SARS CoV-2 Omicron Variant Deadlier and More Transmissible Than Delta Variant?

Bao V Duong et al. Int J Environ Res Public Health. .

Abstract

Genetic variants of severe acute respiratory syndrome coronavirus (SARS-CoV-2) have been globally surging and devastating many countries around the world. There are at least eleven reported variants dedicated with inevitably catastrophic consequences. In 2021, the most dominant Delta and Omicron variants were estimated to lead to more severity and deaths than other variants. Furthermore, these variants have some contagious characteristics involving high transmissibility, more severe illness, and an increased mortality rate. All outbreaks caused by the Delta variant have been rapidly skyrocketing in infection cases in communities despite tough restrictions in 2021. Apart from it, the United States, the United Kingdom and other high-rate vaccination rollout countries are still wrestling with this trend because the Delta variant can result in a significant number of breakthrough infections. However, the pandemic has changed since the latest SARS-CoV-2 variant in late 2021 in South Africa, Omicron. The preliminary data suggest that the Omicron variant possesses 100-fold greater than the Delta variant in transmissibility. Therefore, this paper aims to review these characteristics based on the available meta-data and information from the first emergence to recent days. Australia and the five most affected countries, including the United States, India, Brazil, France, as well as the United Kingdom, are selected in order to review the transmissibility, severity and fatality due to Delta and Omicron variants. Finally, the vaccination programs for each country are also reviewed as the main factor in prevention.

Keywords: COVID-19; Delta variant; Omicron variant; SARS-CoV-2; severity and mortality; transmissibility; variants of concern.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Comparison structure of SARS-CoV-2 and Delta variant.
Figure 2
Figure 2
The new COVID-19 variant: Omicron (B.1.1.529).
Figure 3
Figure 3
Total cases in Australia and the most affected countries from 4 January 2020 to 22 March 2022 [64].
Figure 4
Figure 4
Total cases in proportion to population in Australia and the most affected countries from the first emergence to March 2022.
Figure 5
Figure 5
New South Wales local COVID-19 cases from 7 to 14 August 2021 (accessed 14 August 2021) [66].
Figure 6
Figure 6
New South Wales cases by different age groups (accessed 8 September 2021) [66].
Figure 7
Figure 7
The timeline of SAR-CoV-2 cases in Australia and the most affected countries from 26 October 2020 to 21 March 2022: (a) Delta variant; (b) Omicron variant.
Figure 8
Figure 8
Delta variant droplet transmission.
Figure 9
Figure 9
Delta variant aerosol transmission.
Figure 10
Figure 10
Comparison between Delta and Omicron outbreaks in the most affected countries and Australia: (a) cases by Delta variant; (b) cases by Omicron variant.
Figure 11
Figure 11
SARS-CoV-2 sequences by variant in Australia and the most affected countries from 26 October 2020 to 21 March 2022: (a) Australia, (b) Brazil, (c) France, (d) India, (e) the UK, and (f) the US.
Figure 12
Figure 12
Hospitalized cases comparison by age group between the current Delta and previous outbreaks in Australia [66].
Figure 13
Figure 13
The comparison of severity during the peaks of Delta and Omicron outbreaks in: (a) Australia, (b) France, (c) the UK, and (d) the US.
Figure 13
Figure 13
The comparison of severity during the peaks of Delta and Omicron outbreaks in: (a) Australia, (b) France, (c) the UK, and (d) the US.
Figure 14
Figure 14
Total deaths in Australia and the most affected countries from 4 January 2020 to 22 March 2022 [64].
Figure 15
Figure 15
Total deaths proportion to population in Australia and the most affected countries from the first emergence to March 2022.
Figure 16
Figure 16
Mortality during the peak of Delta outbreaks in: (a) Australia, (b) Brazil, (c) France, (d) India, (e) the UK, and (f) the US [64].
Figure 17
Figure 17
Mortality during the Omicron outbreaks in Australia and the most affected countries from 6 January to 21 March 2022 [64].
Figure 18
Figure 18
The vaccination programs in Australia and the most affected countries from the beginning to March 2022: (a) Australia, (b) Brazil, (c) France, (d) India, (e) the UK, and (f) the US.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Hasnain M., Pasha M.F., Ghani I. Combined measures to control the COVID-19 pandemic in Wuhan, Hubei, China: A narrative review. J. Biosaf. Biosecur. 2020;2:51–57. doi: 10.1016/j.jobb.2020.10.001. - DOI - PMC - PubMed
    1. Yang R., Gui X., Gao S., Ke H., Xiong Y. Clinical progression and changes of chest CT findings among asymptomatic and pre-symptomatic patients with SARS-CoV-2 infection in Wuhan, China. Expert Rev. Respir. Med. 2021;15:411–417. doi: 10.1080/17476348.2021.1840358. - DOI - PubMed
    1. Duan S., Zhou M., Zhang W., Shen J., Qi R., Qin X., Yu H., Zhou C., Hu Q., Yu X.-J. Seroprevalence and asymptomatic carrier status of SARS-CoV-2 in Wuhan City and other places of China. PLoS Negl. Trop. Dis. 2021;15:e0008975. doi: 10.1371/journal.pntd.0008975. - DOI - PMC - PubMed
    1. Dash D.P., Sethi N., Dash A.K. Infectious disease, human capital, and the BRICS economy in the time of COVID-19. MethodsX. 2021;8:101202. doi: 10.1016/j.mex.2020.101202. - DOI - PMC - PubMed
    1. Khurshid A., Khan K. How COVID-19 shock will drive the economy and climate? A data-driven approach to model and forecast. Environ. Sci. Pollut. Res. 2021;28:2948–2958. doi: 10.1007/s11356-020-09734-9. - DOI - PMC - PubMed

Publication types

Supplementary concepts