In December 2021, we investigated a COVID-19 outbreak in a German high school, marking the first case of the previously rare viral variant B.1.640.2, potentially originating from Cameroon. The full-length SARS-CoV-2 sequences from infected individuals were classified within the B.1.640.1 and B.1.640.2 pangolin lineages (IHU variant). The Robert Koch Institute confirmed that this variant had been identified only once before in Germany, without an associated outbreak.

The index case, an adult returning from a three-week development aid mission in the Republic of the Congo, introduced the atypical variant to the school via his children. This led to further transmission to a vulnerable hospital ward and subsequently several other communities. A unique biphasic pattern in CT-value courses over 3-4 weeks was observed in all cases, coinciding with the period immediately following the mandatory 10-14 day quarantine, underscoring the distinctive features of the B.1.640.2 variant.

Additionally, it was established that the index case and another known case likely infected each other on an airplane, highlighting the variant's transmission dynamics. These findings underscore the unpredictability of SARS-CoV-2 variant emergence and their potential introduction into new geographical areas and vulnerable settings from abroad.

Despite these challenges, early management strategies and research into the clinical signs associated with self-quarantine proved effective in controlling the outbreak. This instance further illustrates the critical importance of continuous vigilance and preparedness in the global response to emerging SARS-CoV-2 variants.