Omicron Variant: Prevalence, Transmissibility, and Pathogenicity

Abstract

The Omicron variant that caused a huge surge in COVID-19 infections worldwide has been studied in terms of prevalence, infectivity, and virulency. The first study conducted in South Africa showed the low pathogenic nature of the Omicron variant compared to the Delta and original Wuhan variants. The deaths, ICU admissions, length of the hospital stay, and also the need of oxygen support all reduced greatly in Omicron infected patients as compared to the earlier variants. The share of the Omicron variant in Delhi (India) rose rapidly. In two weeks (December 21, 2021-January 3, 2022), the omicron prevalence increased from 38% to 81%. Because of the Omicron variant, in the last week of January 2022, Delhi’s caseload surged nine folds. The cases analysed in Delhi, Mumbai, and throughout India revealed that the number of deaths during the Omicron wave was much lower compared to the Delta and Wuhan variants.

Prevalence and Pathogenicity of Omicron Varian

“…2). On December 28, the cases surged to 9,184 daily new infections [23]. The apparent surge was due to the higher Omicron prevalence of 39.9% reported on December 27.…”

“…Vaccine breakthrough infections that occurred in India in HCWs [21] and the general population [22] have been discussed. The dynamics of the spread and severity of the Omicron variant have also been described [23], [24]. In the city of Sendai (Japan), a new Omicron subvariant has been identified which has genetic information of both the B.A.1 and B.A.…”

Omicron Wave in India, Mumbai, and Delhi: Prevalence and Pathogenicity

“…The new infections recorded till December 27 were still at the baseline below 8,000 (Fig. 2 and [26]). This number is baseline infections recorded when the second pandemic wave receded.…”

“…This number is baseline infections recorded when the second pandemic wave receded. When the share of the Omicron variant increased to 39.9% on December 27, the apparent Omicron surge was noticed as the new registered cases increased to 9,184 on December 28 [26], [27]. On January 10, the Omicron share in the total new daily cases rose to 78.53% which was reflected in the high caseload (167,067) [27] registered on this date as shown in Fig.…”

“…A mere 2% prevalence of Omicron in Mumbai has not caused any noticeable increase in infections until 20 th December. On this date, 191 new cases were reported [26] which remained the baseline cases recorded when the second Delta wave receded. An increase in the new infections was apparent after December 21 (312 cases).…”