Explained: Omicron rising, but Delta still dominant

Most cases in Europe

Data from the World Health Organization (WHO) shows that seven of the ten countries with the highest number of cases in the last seven days are in Europe, the other three being the United States, South Africa and Vietnam.

Omicron has now spread to 106 countries, the WHO has reported. In the week between December 13 and 19, more than 41.77 lakh new cases were detected across the world, of which over 26.11 lakh (63%) came from Europe, the WHO said in its weekly report.

Besides the UK, Spain too recorded its highest-ever single day case count of nearly 50,000 on Tuesday, while France said it expected the daily count of cases to exceed one lakh very soon due to the spread of the Omicron variant. The country is currently averaging over 50,000 cases a day.

For the time being, though, both France and Spain have decided against any fresh restrictions for the Christmas. Germany and Portugal have announced post-Christmas restrictions. In Germany, no more than 10 people would be allowed in private gatherings from December 28, while nightclubs would shut down, the BBC reported. Portugal has ordered pubs and nightclubs to close down from December 26.

Vaccines

Israel is preparing to provide a fourth dose of the coronavirus vaccine to its healthcare workers and older population. Coronavirus cases have been rising in Israel as well, with more than 900 infections being reported on Tuesday.

Pharmaceutical major AstraZeneca said it had begun work on developing an Omicron-specific vaccine. “Together with Oxford University, we have taken preliminary steps in producing an Omicron variant vaccine, in case it is needed and will be informed by emerging data,” the company said in a statement.

Delta still dominant

Although most of the new cases around the world, especially in Europe, are believed to have been caused by the Omicron variant, the WHO said Delta continued to be the dominant variant of concern globally.

Of the over 10.51 lakh genome sequences done between October 20 and December 19 across the world, close to 10.1 lakh, or about 96%, were found to be of the Delta variant, and only about 17.000 (less than 2%) were of Omicron.

The WHO numbers was based on the sequences deposited in public databases such as GISAID. Individual countries have confirmed many more Omicron cases. The UK, for example, has reported more than 45,000 confirmed cases of Omicron infection till now. Not all genome sequences are immediately deposited in the global public databases.

But the WHO said the Delta variant had not completely gone away.

“Following the classification of Omicron as a variant of concern, many countries have adopted targeted sequencing strategies to detect the variant. The change in sampling strategy, away from community-based surveillance sequencing, may result in biases in the proportions of variants being reported. Thus, the recent declines in the proportion of Delta variant reported by some countries may reflect changes in sampling strategy, rather than declines in the proportion of Delta variant cases among all Covid-19 cases,” the WHO said.

It said the overall risk related to the Omicron variant remained “very high”.

“Recent evidence indicates that Omicron variant has a growth advantage over the Delta variant and is spreading rapidly… It remains uncertain to what extent the observed rapid growth rate can be attributed to immune evasion, intrinsic increased transmissibility, or a combination of both. There are still limited data on the clinical severity of Omicron. Hospitalisations in the UK and South Africa continue to rise, and given rapidly increasing case numbers, it is possible that healthcare systems may become overwhelmed,” it said.

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