Omicron variant now causing up to 15% of Dutch coronavirus infections; Vaccines less effective against it

The Omicron variant of the SARS-CoV-2 coronavirus now accounts for 10 to 15 percent of infections in the Netherlands, RIVM director Jaap van Dissel told the Tweede Kamer on Tuesday. Without a booster shot, the current Covid-19 vaccines used in the Netherlands are expected to be about four to five times less effective preventing an Omicron variant infection than a Delta variant infection. The Delta variant has been the most dominant variant in the country since July. 

The Omicron variant is already causing a slightly larger share of infections in Amsterdam, Van Dissel said. It is expected to displace the Delta variant to become the dominant variant in the country by the end of the year.

Van Dissel also said that 85 percent of the people who were infected with the Omicron variant were fully vaccinated. This figure was about 62 percent regarding the Delta variant. People who previously were infected with coronavirus also seemed to be less protected against the Omicron variant, he said. Of the group that contracted the Omicron variant, about 3 percent previously recovered from the coronavirus. With the Delta variant this was slightly more than 1 percent.

Although a full course of vaccination provides reasonable protection against the Omicron variant in the short term, the effectiveness is expected to decrease quickly, Van Dissel said. A booster shot can "upgrade" the protection level against the Omicron variant. The effectiveness of the booster shot will also decrease over time, but less quickly, Van Dissel predicted.

"The vaccine was made against the Wuhan variant, which has not been circulating for a long time," explained Van Dissel. The Delta and Omicron variants are so different that the vaccine no longer recognizes them well, he added.

Van Dissel emphasized that it is still uncertain whether Omicron is as pathogenic as the Delta variant. During his presentation to the public health committee, he also showed the same graphs he showed Cabinet members last week, which showed that an extension of the evening lockdown could likely lead to over 4,000 Covid-19 patients requiring intensive care at the same time. Currently, the ICU system has a maximum capacity of about 1,200 spaces, with roughly 700 ready for Covid-19 cases.

Shortly after Van Dissel’s presentation to some Cabinet members, ministers and mayors were asked to attend emergency meetings about the state of the pandemic in the Netherlands. Later on Saturday, the Netherlands announced a full lockdown to last until January 14.