THL monitors coronavirus variants circulating in Finland – sublineage XBB.1.5 of Omicron variant not yet detected
The XBB.1.5 sublineage of the Omicron variant of COVID-19 was rapidly becoming more common in the United States in December 2022. According to the monitoring data of the Finnish Institute for Health and Welfare (THL), the XBB.1.5 sublineage has not been found in Finland. THL is also actively monitoring the situation due to the increasing number of infections in China and assessing the need for more effective monitoring of virus variants.
Since December 2020, the occurrence of various coronavirus variants in Finland has been monitored by means of “whole-genome sequencing”. It is used to identify the lineages of viruses circulating in the population and the mutations occurring in them.
At the moment, THL sequences around 350–400 coronavirus positive samples from different hospital districts every week. The number of samples to be sequenced corresponds to approximately 3.5 per cent of the coronavirus positive samples confirmed by laboratory testing in Finland.
Monitoring makes it possible to reliably identify the virus variants circulating in Finland. The results are reported to the National Infectious Diseases Register and as a summary to THL’s website after 2–3 weeks from sample collection.
The XBB.1.5 sublineage is not known to cause a more serious disease compared to other Omicron virus variants
Omicron’s XBB.1.5 sublineage is believed to originate in the United States, but according to media information, it has also been found in the United Kingdom and India and based on data from the international coronavirus sequence database, also in Israel and Trinidad and Tobago.
“The viruses of the XBB.1.5 sublineage are estimated to be highly infectious, but they are not currently known to cause a more serious disease than other Omicron variants,” says Jari Jalava, Chief Specialist at THL.
In Finland, the majority of coronavirus findings have represented the BA.5 variant of Omicron during the second half of 2022. Early forms of the XBB sublineage constituted less than 10% of the sequenced samples in Finland at the end of last year.
The Omicron XBB is a combination of the Omicron sublineages BA.2.10.1 and BA.2.75. The XBB.1.5 sublineage, which has become common in the United States, originated from the XBB sublineage.
Information on coronavirus variants circulating in Finland is also obtained through wastewater monitoring. The first wastewater observations on the early forms of the XBB sublineage of the Omicron variant were made in Espoo and Helsinki at the end of October 2022.
The same variants circulate in China and in Europe
The number of coronavirus infections has increased considerably in China and the growth is expected to continue in the coming weeks. The situation is the result of the country’s relaxed restrictions and the population’s low level of protection against the disease.
According to current information, the same coronavirus variants already circulating in Europe also exist in China.
The European Centre for Disease Prevention and Control (ECDC) states that China has started to report more and more sequence data towards the end of 2022. The majority of samples taken in December 2022 represented the Omicron sublineages BA.5.2 (35%) and BF.7 (24%). Omicron XBB’s share of the reported sequence findings was 4%. The XBB.1.5 sublineage has not yet been found.
“New forms of the virus can spread quickly around the globe. During the coronavirus pandemic, we have seen that it is practically impossible to stop infectious virus variants at national borders. The best way to protect yourself against coronavirus is to get the recommended coronavirus vaccinations. All coronavirus vaccines used in Finland provide good protection against serious forms of the disease,” Jalava says.
Further information
SARS-CoV-2 coronavirus genome monitoring (in Finnish)
Coronavirus variants in wastewater
Jari Jalava
Chief Specialist
THL
tel. +358 29 524 6629
[email protected]
