ECDC Epidemiological Update: COVID-19 Transmission in the EU/EEA & SARS-CoV-2 Variants

#17,661

Since the world declared the COVID emergency to be over more than a year ago, and most countries have systematically dismantled their surveillance, testing, and reporting capabilities (see No News Is . . . Now Commonplace), we find ourselves in the unenviable position of trying to judge the significance of new, emerging variants, with precious little real-time data.

COVID rates, and hospitalizations, do appear to be rising.  But exactly what is driving those increases is difficult to say.  Several new variants have emerged, but the lack of testing, and reporting, makes drawing firm conclusions difficult. 

There are conflicting reports, and some clearly worried officials (see UKHSA To Move COVID/Flu Jabs Forward Due To Concerns Over BA.2.86), but for now the official line from most health agencies is `there is no evidence' that these new variants pose any greater threat than previous ones.

Today the ECDC has published a lengthy epidemiological update, which - among other things - calls for better surveillance and reporting in the face of these emerging variants, and for an aggressive COVID vaccination campaign for the most vulnerable this fall. 

They also provide a fairly optimistic assessment on the likely impact of the highly mutated BA.2.86 variant, although they admit that it is based on very limited information. 

Due to its length, I've only posted the highlights, and an excerpt from the BA.2.86 risk assessment. Follow the link to read it in its entirety.

Epidemiological update: COVID-19 transmission in the EU/EEA, SARS-CoV-2 variants, and public health considerations for Autumn 2023

Epidemiological update
7 Sep 2023

In recent weeks, signals of SARS-CoV-2 transmission have increased from previously very low levels in the EU/EEA.

Key messages

• In recent weeks, signals of SARS-CoV-2 transmission have increased from previously very low levels in the EU/EEA. Factors unrelated to the genetic evolution of SARS-CoV-2 likely contributed to observed increases in epidemiological indicators, such as large gatherings and increased travel during the seasonal holidays, as well as waning levels of immunological protection against infection – but not severe disease – in the population.
• Nonetheless, SARS-CoV-2 remains capable of acquiring mutations that facilitate its continued circulation at unpredictable times throughout the year. Recently observed increases in SARS-CoV-2 transmission have coincided with the emergence and subsequent dominance of a group of related Omicron sub-lineages, XBB.1.5-like variants carrying the F456L mutation.
• In August 2023, sporadic detections of a new highly mutated Omicron sub-lineage, BA.2.86, were reported within and outside the European Union/European Economic Area (EU/EEA). Although very few case detections have been confirmed globally, low-level community transmission of this variant is suspected in multiple countries. In terms of mutations, the variant is highly divergent from currently circulating SARS-CoV-2 variants bringing the possibility of increased reinfections if it successfully outcompetes currently circulating variants in the EU/EEA.
• There is no indication that infection with XBB.1.5-like+F456L variants or BA.2.86 are associated with more severe disease or a reduction in vaccine effectiveness against severe disease when compared to currently circulating variants. Older people and those with underlying conditions remain at increased risk of severe outcomes if infected.
• The completeness and timeliness of epidemiological and virological COVID-19 surveillance data in the EU/EEA has decreased significantly in the past year. The emergence of BA.2.86 underscores the importance of continued vigilance for SARS-CoV-2 by strengthening representative surveillance systems in primary and secondary care to detect trends in COVID-19 transmission and severe disease. Where possible, all SARS-CoV-2-positive specimens from representative surveillance systems should be sequenced and reported to the Global Initiative on Sharing All Influenza Data (GISAID) and/or The European Surveillance System (TESSy) to facilitate the continued assessment of circulating variants.
• Vaccination efforts should focus on protecting those at risk of progression to severe disease, e.g. people aged over 60 years and other vulnerable individuals irrespective of age (such as people with underlying comorbidities or immunocompromised conditions). As we approach autumn vaccination campaigns, countries should carefully consider factors that have previously limited booster vaccine uptake and address them. So that vaccination campaigns adequately protect population groups that remain at risk of severe COVID-19 disease, countries should assess their readiness to detect and respond to epidemiological signals of increased COVID-19 transmission. They should also assess their ability to identify and reach high-risk groups. Communication campaigns that engage healthcare professionals and the wider public play a critical role in highlighting the importance of staying up to date with COVID-19 vaccination for high-risk groups

(SNIP)

As of 24 August, ECDC has classified BA.2.86 as a variant under monitoring (VUM) because of a high number of spike protein mutations that were predicted to evade vaccine-induced immunity against SARS-CoV-2 infection [10]. It is still too early to confirm that these mutations confer a growth advantage for BA.2.86, and it is not yet possible to predict the impact of these mutations on the variant’s transmission fitness relative to currently circulating XBB-derived variants. Across the EU/EEA, the vast majority of the population has developed hybrid immunity through a combination of vaccination and at least one prior infection.

Preliminary pseudovirus neutralisation studies for BA.2.86 show that serum from individuals with hybrid immunity—particularly following booster vaccination and infection with recent XXB-derived variants—is able to effectively neutralise BA.2.86 in vitro, indicating that a combination of hybrid immunity coupled with recent infection confers some protection against BA.2.86 infection [11,12].

It is unlikely that BA.2.86 variants are associated with any increase in infection severity compared to currently circulating variants, or a reduction in vaccine effectiveness against severe disease. However, older individuals and those with underlying conditions remain at increased risk of severe outcomes, if infected. Given the very limited number of confirmed BA.2.86 detections globally, epidemiological studies to formally assess severity and vaccine effectiveness relative to other circulating variants are not yet available.

          (Continue . . . )

While there are some encouraging signs (see here, and here) that BA.2.86 may not be the game-changer that many first feared, ultimately, we probably won't know for sure for weeks or perhaps months. 

Meanwhile, viral evolution never stops.