News of the new coronavirus variant Omicron triggered alarm and a sell-off last week in financial markets as countries imposed new curbs over fears the strain could resist vaccinations and upend a nascent economic re-opening after a two-year slowdown.

The World Health Organization (WHO) warned that deciding the severity level of Omicron could take "days to several weeks" in the absence of information that its symptoms differed from those of other variants.

Asian markets and oil prices regained some composure as investors settled in for a few weeks of uncertainty as they await more details.

On November 25, South African scientists announced the detection of the new variant, scientifically known as B.1.1.529. Here are some facts to get you up to speed about Omicron. 

1. Why is Omicron so worrying?

The new variant contains large number of mutations which may reduce vaccine effectiveness considerably.

It has more than 30 mutations of the spike protein that viruses use to get into human cells – about double the number of Delta's. It makes this variant substantially different from the original coronavirus that current COVID-19 vaccines were designed to counter.

However, its actual ability in terms of transmissibility, severity and vaccine resistance is still unclear.

2. Which countries have reported cases of the new variant?

As of November 29, dozens of countries have confirmed cases of the variant.

Potentially more contagious than previous variants, Omicron has been detected in countries and regions including Australia, Belgium, Botswana, Britain, Canada, Denmark, France, Germany, Israel, Italy, the Netherlands, South Africa and China's Hong Kong. 

3. What measures have been taken since the variant's detection?

Australia, Brazil, Canada, the European Union, Iran, Japan, Thailand, the United States and other countries and regions have already imposed travel restrictions on flights from South Africa as they seek to buy time to assess whether the Omicron variant is more transmissible than the currently dominant Delta variant.

Israel announced it would ban the entry of foreigners and re-introduce counterterrorism phone-tracking technology. Japan has also announced the suspension of arrivals of all foreign nationals starting from November 30.

South Africa has denounced the measures as unfair and potentially harmful to the economy, saying it was being punished for its scientific ability to identify variants early.

4. How dangerous is the new variant compared to others such as Delta variant?

The WHO said it's not yet clear whether Omicron is more easily spread from person to person compared to other variants, even though the number of people testing positive has risen in South Africa where this variant was first detected.

It's also not yet clear whether Omicron causes more severe disease, but preliminary data suggests that there are increasing rates of hospitalization in South Africa, which however may be due to increasing overall numbers of people becoming infected.

The WHO confirmed that there is currently no information to suggest that symptoms associated with Omicron are different from those from other variants, as understanding the level of severity of the Omicron variant will take days to several weeks.

5. Do we need new vaccines especially for Omicron?

As scientists are racing to study Omicron, the pharmaceutical companies have announced efforts to upgrade their vaccine to better combat the new variant.

The mRNA vaccine developers such as Pfizer/BioNTech, Moderna and Johnson & Johnson have been testing the effectiveness of their vaccines against the new variant.

"We expect more data from the laboratory tests in two weeks at the latest," according to Pfizer/BioNTech's statement. The company said the upcoming data will show if their vaccine needs an adjustment for an update.

Chinese vaccine developer Sinovac Biotech said it is studying the variant's influence on its inactivated vaccine and evaluating the necessity for developing a vaccine against Omicron as soon as possible. Another drug maker, CanSino Biologics, said it is paying close attention to Omicron and has dived into the process of data collection and analysis of the variant.

(With inputs from Reuters and Xinhua)