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An outbreak of COVID-19 after a pilgrimage to Medjugorje due to Delta sub-lineages
Alessandra Lo Presti1, Salvatore Rubino2, Gabriele Ibba2
1Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy.
Introduction:
A COVID-19 outbreak occurred at the end of October 2021 among pilgrims returning from Medjugorje (Bosnia and Herzegovina).
Methodology:
Whole genome sequencing (WGS) of SARS-CoV-2, epidemiological data, and phylogenetic analysis were used to reconstruct outbreak dynamics.
Results:
The results suggest that only in one case, associated with the SARS-CoV-2 sub-lineage AY.9.2, it is possible to trace back the place of contagion to Medjugorje, while the other cases were likely to be acquired in the country of origin.
Conclusions:
The combined use of phylogenetic data derived from WGS, and epidemiological data allowed us to study epidemic dynamics and to formulate a possible hypothesis on the place of exposure to SARS-CoV-2. The identification of different sub-lineages of the SARS-CoV-2 Delta variant also suggested that different chains of transmission contributed to the outbreak.
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