Omicron variant responsible for 91% of Amsterdam coronavirus infections

An analysis of a random sample of positive coronavirus test swabs showed that nearly 91 percent of infections in the greater Amsterdam area were caused by the newer, highly contagious Omicron variant. The variant has been responsible for a majority of infections in the Amsterdam area since at least December 22, and became dominant in the Netherlands about a week later.

A total of 69 test samples collected were found to contain the Omicron variant out of 76 samples analyzed at random, according to the ARGOS Consortium. These were collected by the regional branch of the GGD serving Amsterdam, Aalsmeer, Amstelveen, Diemen, Ouder-Amstel, and Uithoorn.

About 10 percent of samples analyzed on December 12 contained the Omicron variant, which grew to become just shy of 50 percent by December 20. A week later, the figure was at 80 percent.

As the Omicron variant displaced the Delta variant in the region, a corresponding increase in infections was also witnessed. An average of 1,065 residents of Amsterdam tested positive for the coronavirus each of the past seven days, a 42 percent increase compared to the previous week, according to raw data from the RIVM. The average was at 874 in the seven-day period ending November 28, when daily infections in the Netherlands was at a peak but the Omicron variant had only just been discovered in the country.

With the variant now dominant in the Netherlands, a month-long trend in declining coronavirus figures has reversed. Nearly 15,000 infections were reported each of the past seven days, a 23 percent increase compared to the previous period, recent data from the RIVM showed.

ARGOS stands for Amsterdam Regional Genomic Epidemiology and Outbreak Surveillance. The group includes researchers from the GGD Amsterdam, the Amsterdam University Medical Center, and inBiome.