A recent epidemiological update by the European Center for Disease Prevention and Control (ECDC) indicated that a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron sublineage was likely to increase coronavirus disease 2019 (COVID-19) case numbers.
The ECDC has classified SARS-CoV-2 BQ.1 variant and its sublineages as a variant of interest (VOI). BQ.1 is a sublineage of BE.1.1.1, a sublineage of Omicron BA.5, with additional amino acid substitutions in the spike protein’s receptor-binding domain (RBD). The BQ.1 sublineage also has a sublineage designated BQ.1.1. The BQ.1.1 sublineage carries R346T as an additional change compared to BQ.1.
Recently, a preprint study evaluated the neutralization of SARS-CoV-2 pseudoviruses by sera of individuals triple-vaccinated for COVID-19, who also had an infection with Omicron BA.1, BA.2, or BA.5 variant. The study observed that BQ.1 was associated with a nearly four-fold decline in neutralization activity relative to BA.5. It also reported that the BQ.1 variant was resistant to therapeutic monoclonal antibodies (mAbs) such as Evusheld and bebtelovimab.
SARS-CoV-2 BQ.1 in Europe
Data from the Global Initiative on Sharing Avian Influenza Data (GISAID) EpiCoV show that BQ.1 and BQ.1.1 are present at significant levels in the European Union (EU) or European Economic Area (EEA). France, Belgium, Italy, The Netherlands, and Ireland are the EU/EEA countries with the highest reports of the variant in week 40 of 2022. The United Kingdom and Switzerland are the non-EU/EEA countries with the highest reports of this variant.
It has been estimated that the variant accounted for 11% of COVID-19 cases in the United States (US) during week 42, 2022. Moreover, the variant may be present at high levels but remains undetected due to gaps in global sequencing coverage. The current levels of the BQ.1 are not high enough to impact the epidemiologic situation in affected countries.
Any significant effect on case numbers due to BQ.1 may occur in the forthcoming weeks or months based on the current BQ.1 proportion in each country. Growth advantage estimates of SARS-CoV-2 BQ.1 revealed that the doubling time for COVID-19 cases caused by the variant is about a week or less, varying across settings. Immune escape is likely to drive the observed growth rate.
It might also be possible that BQ.1 has higher intrinsic transmissibility than BA.5. Currently, there are no signs that BQ.1 causes much more severe disease than BA.5. Based on the observations on the increasing growth rate of BQ.1, BQ.1 will likely increase COVID-19 numbers in the coming weeks/months in the EU/EEA.
Modeling indicated that more than 50% of COVID-19 cases would be caused by BQ.1 or BQ.1.1 by early December 2022 in the EU/EEA. Further, most COVID-19 cases (>80%) will be due to the BQ.1 variant and its sublineage by early 2023. It is anticipated that countries with the highest burden of BQ.1 will probably witness the predominance of the variant sooner than other nations.
The BQ.1 variant may become dominant in the EU/EEA by the end of 2022, coinciding with the winter holidays. The anticipated increase in social contacts and case numbers due to the dominant BQ.1/BQ.1.1 sublineages during winter might lead to high viral transmission and a consequent public health concern.
The ECDC recommends that countries be vigilant for signs of increasing BQ.1 in circulation. Besides, genomic sequencing and sensitive testing policies are necessary to accurately estimate the burden of these variants contributing to increases in severe outcomes in the population. Countries must continue strengthening existing sentinel systems and collect information on lab-confirmed cases, hospitalizations, admissions to intensive care units, and hospital bed occupancy.
Countries must continue sequencing positive samples and share data in a timely manner. Improvements in vaccination coverage must be ensured, particularly among at-risk individuals who have not completed recommended schedules. The winter/fall vaccination campaigns should offer additional vaccine boosters, with priority for individuals at risk of severe disease.
New SARS-CoV-2 Omicron-adapted vaccines have been approved for use as boosters in those aged 12 or above in the EU/EEA. The variant-adapted vaccines must be restricted for use as boosters, and current mAbs based on the original SARS-CoV-2 strain may still be continued. Existing monovalent vaccines based on the original strain may still be used if variant-adapted vaccines are unavailable.