THL: Proportion of the EG.5 variant in coronavirus infections rising – epidemic situation calm

Publication date 15 Sep 2023

The Omicron XBB sub-variant EG.5 is spreading globally. The proportion of the sub-variant in coronavirus infections detected in Finland is growing as well. The epidemic situation remains calm.

According to the coronavirus genome surveillance carried out by the Finnish Institute for Health and Welfare (THL), the EG.5 variant was first detected in Finland in early June. In July, it accounted for around 5% of all detected infections, and in August, the proportion rose to approximately 27%. 

Combined, the different XBB sub-variants account for 95% of all detected infections. XBB sub-variants efficiently evade the immunity generated by previous vaccines, contributing to their pathogenicity in the population. The different XBB sub-variants are very similar in terms of transmissibility and pathogenicity. The EG.5 and its sub-variants contain a spike protein mutation that enhances the virus's ability to evade immunity. It can therefore spread more easily than other current variants. According to current information, the EG.5 variant does not cause more severe symptoms than the other circulating variants. 

Small quantities of the BA.2.86 variant have also been reported around the world. This new variant has already been detected in Swedish and Danish patient samples and Norwegian wastewater analyses. The variant has been reported to have caused a small epidemic in a UK long-term care facility. Most of the patients did not require hospitalisation, and no one died. 

The BA.2.86 variant is being monitored due to its exceptional spike protein structure. It has not yet been detected in Finland. 

"It is likely that it will also be detected in Finland during the autumn. However, it is still difficult to assess how it's going to spread," says Erika Lindh, Senior Researcher at THL. 

"As the number of coronavirus samples analysed is relatively small both in Finland and globally, variants are detected with a greater delay than before. The number of cases must be relatively high before conclusions can be drawn on the epidemiological significance of an individual variant or the severity of the disease it causes," Lindh continues.

THL continuously monitors the coronavirus epidemic situation and the accumulated research data. 

EG.5 now the most prevalent coronavirus variant in wastewater 

The total amount of coronavirus RNA in Finnish wastewater remained at a steady low level throughout August. In early September, the amount of coronavirus in wastewater started to rise slightly in all monitored localities except Tampere.

Based on wastewater data, the EG.5 variant emerged as the prevailing variant in Finland in early August. 

According to the latest data, the relative proportion of the EG.5 variant now exceeds 50% in all monitored localities. In addition to the EG.5 variant, the CH.1.1. and other XBB sub-variants are still detected in wastewater. In late August, these were still detected in Helsinki, Jyväskylä, Kuopio, Tampere and Turku, but no longer in Espoo, Joensuu, Oulu and Vaasa, where the EG.5 was the only coronavirus variant detected.

Wastewater surveillance was on summer break during the last three weeks of July, so there is no RNA quantity and variant data for that period.

The BA.2.86 variant has not yet been detected in Finnish wastewater. 

"THL monitors the situation weekly and continues to develop wastewater surveillance. In addition to coronavirus surveillance data, we aim to be able to provide up-to-date information on the incidence of influenza and RS viruses in Finnish wastewater," says Tarja Pitkänen, Chief Specialist at THL.

Further information

Genomic surveillance of SARS-CoV-2

Detected coronavirus variants in wastewater

Weekly report on wastewater surveillance for coronavirus (in Finnish)

Erika Lindh (coronavirus variants)
Senior Researcher, Finnish Institute for Health and Welfare
[email protected]

Tarja Pitkänen (coronavirus wastewater surveillance)
Chief Specialist, Finnish Institute for Health and Welfare
[email protected]

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