Globally, there has been a 4% increase in the number of new deaths from in week 2 January (10 – 16, 2022) compared to the previous week
Geneva: As of January 20, 2022, the Omicron variant has been identified in 171 countries. It has a substantial growth advantage over Delta, and it is rapidly replacing Delta globally. There is now significant evidence that immune evasion contributes to the rapid spread of Omicron, but further research is needed to better understand the relative contribution of intrinsic increased transmissibility and immune evasion in explaining transmission dynamics.
The Omicron variant comprises four lineages including B.1.1.529, BA.1, BA.2 and BA.3. While the BA.1 lineage has previously been the most dominant, recent trends from India, South Africa, the United Kingdom, and Denmark suggest that BA.2 is increasing in proportion. Drivers of transmission and other properties of BA.2 are under investigation but remain unclear to date, the World Health Organization stated here today.
WHO stressed that studies are needed to better understand the properties of BA.2, including comparative assessments of BA.2 and BA.1 for key characteristics such as transmissibility, immune escape and virulence.
Omicron has been found to have a significant growth advantage, higher secondary attack rates and a higher observed reproduction number compared to Delta.
There is evidence that the Omicron variant infects human bronchus tissue faster and more efficiently than Delta and outcompetes Delta in competition experiments using cells derived from the human nose, but not in lung-derived cells. This points at a predominance of viral replication in the upper respiratory tract that may confer, at least to some extent, a transmission advantage independent of immune evasion.
The overall threat posed by Omicron largely depends on four key questions: (i) how transmissible the variant is; (ii) how well vaccines and prior infection protect against infection, transmission, clinical disease and death; (iii) how virulent the variant is compared to other variants; and (iv) how populations understand these dynamics, perceive risk and follow control measures, including public health and social measures (PHSM).
Disease severity
Globally, there has been a 4% increase in the number of new deaths from in week 2 January (10 – 16, 2022) compared to the previous week, with highest increases in the South-East Asia Region (12%) and the Region of the Americas (a 7% increase) of WHO.
Using samples from the lower respiratory tract, researchers at Hong Kong University found that the Omicron variant replicates up to 70 times faster in the human bronchi compared to the Delta variant and the wild-type SARS-CoV-2 virus. In contrast, the Omicron variant showed relatively much slower replication in the lung. A similar finding was reported in the United Kingdom where Omicron showed a reduction in replication kinetics compared to Delta and the original SARS-CoV-2 strain. These observations could further support a reduction in intrinsic severe clinical presentation of patients infected with the Omicron variant.
In terms of symptoms, preliminary data from the United Kingdom show that Omicron infections appear to be associated with more frequent sore throat than for Delta, and reduction in frequency in loss of smell and taste (31), although these findings need to be interpreted with caution given increase circulation of other respiratory viruses, and potential co-infection.
Nevertheless, despite lower severity, significant increases in hospitalization, severe disease and death are occurring and likely to continue in the coming weeks, with significant pressure on health services, given the high incidence levels of community transmission. Moreover, current evidence about severity and hospitalization comes largely from countries with high levels of population immunity (post-infection and vaccine-derived), and there remains uncertainty about the severity of Omicron in populations with lower vaccination coverage and prior exposure to other SARS-CoV-2 variants.
Based on the currently available evidence, the overall risk related to Omicron remains very high, WHO stated. Omicron has a significant growth advantage over Delta, leading to rapid spread in the community with higher levels of incidence than previously seen in this pandemic. Despite a lower risk of severe disease and death following infection than previous SARS-CoV-2 variants, the very high levels of transmission nevertheless have resulted in significant increases in hospitalization, continue to pose overwhelming demands on health care systems in most countries, and may lead to significant morbidity, particularly in vulnerable populations.
The case incidence of COVID-19 continues to increase globally with a 20% weekly increase in week 2 (January 10-16, 2022) compared to the previous week. However, the global rate of increase does appear slower given that there was a 55% increase that was reported for week 1 (January 3-9, 2022 ) compared to week 52 (December 27, 2021–January 2, 2022).
During week 2, the South-East Asia Region and the Eastern Mediterranean Region of WHO reported the highest increases in case incidence of 145% and 68%, respectively. However, a decrease of 27% was reported in the African Region following a peak in week 52, 2021.
The large increase in the South-East Asia Region is mainly driven by the increase in the number of cases in India which reported 1 594 160 million new cases compared to 638 872 cases the previous week (a 150% increase). In the Eastern Mediterranean Region, the highest numbers of new cases were reported from Morocco (46 104 vs 31 701 new cases, a 45% increase); Lebanon (45 231 vs 38 112 new cases, a 19% increase) and Tunisia (39 487 vs 13 416 new cases, a 194% increase).
In the WHO European Region, the increase in weekly case incidence has slowed, with a 10% increase in week 2 compared to 31% in week 1 (January 2 – 9, 2022). However, differences within the Region are reported; while a decline or plateauing is starting to be observed in a few countries in Western Europe, many Eastern European and Central Asian countries are seeing high growth rates, with the highest increases seen in week 2 in Kazakhstan (54 927 vs 6672 new cases in week 1, a 723% increase), Uzbekistan (4744 vs 1223 new cases, a 288% increase) and Kosovo (2990 vs 842 new cases, a 255% increase).
The increase in weekly case incidence has also slowed in the WHO Region of the Americas, with a 17% increase as of January 16 compared to 78% as of January 9, mainly driven by the decrease in the number of new cases in the United States of America. However, large increases in case incidence continued to be seen in Central and South America and the Caribbean and Atlantic Ocean Islands, with the largest increases in cases in week 2 reported in Martinique (13 540 vs 1835 new cases, a 638% increase), El Salvador (1343 vs 289 new cases, a 365% increase) and Ecuador (42 992 vs 10 532 new cases, a 308% increase).
In the WHO Western Pacific Region, the rate of increase in case incidence has begun to slow, mainly driven by the trend in Australia. During week 2 of 2022, an increase of 38% was reported while in week 1, a 122% increase compared to their previous week was reported.
In South Africa, where Omicron was first reported and is now the dominant variant, there has been a sustained decrease in reported cases since the peak was reported in mid-December 2021. Moreover, the decline in the incidence of cases seen in much of the southern Africa is now starting to be seen in other countries, particularly those which reported an early introduction of Omicron and rapid replacement of Delta.
Also read:
- Why are experts concerned about Omicron?
- Omicron figures sketchy as just 1% sample is processed for Genome testing
– global bihari bureau
