Omicron has a substantial growth advantage over the Delta strain of COVID-19 and is rapidly replacing Delta globally, particularly because it is able to evade the human immune system, says WHO’s technical briefing paper for member states.

COVID-19, and particularly its Omicron strain, continues to spread, says a technical brief produced by the World Health Organisation. It says that available evidence suggest that the overall risk related to Omicron remains very high.

As of 20 January 2022, the Omicron variant had been identified in 171 countries across all six WHO regions. The briefing paper says that there has been a four per cent increase in the number of new deaths globally in the week between 10 and 16 January 2022 compared to the previous week. The highest increases of 12 per cent has been reported from WHO’s South-East Asia Region that includes India. The Americas region has reported a seven per cent increase.

“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),” the paper says.

The paper says that Omicron has a substantial growth advantage over Delta, and it is rapidly replacing Delta globally, particularly because it is able to evade the human immune system. “There is now significant evidence that immune evasion contributes to the rapid spread of Omicron,” the WHO paper says.

Higher levels of incidence

Experts point out the Omicron has a significant growth advantage over Delta and is 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” says the WHO.

On the question of the effectiveness of vaccines, the paper reiterates that “there is a growing body of evidence on vaccine effectiveness for Omicron, with data available from 15 observational studies from five countries.”

In addition, increased risk of reinfection has been reported by South Africa, the United Kingdom, Denmark, and Israel.

Priority actions suggested by the group for member states (governments) include surveillance and testing, vaccination (with particular focus among populations designated as high priority and prioritising those yet to be vaccinated or incompletely vaccinated), infection prevention and control, public health and social measures, contact tracing and quarantine and risk communication and community engagement.

The WHO group of experts has also recommended travel-related measures that will adjust international travel measures in a timely manner. Simultaneously, it has cautioned against blanket travel bans, saying that this “can adversely impact global health efforts during a pandemic by disincentivizing countries to report and share epidemiological and sequencing data.”