- February 2023
- Giovanni Franzo et al.
Vaccines against PPV1 have been used since the early 80s and have largely been administered in the last 30 years. However, despite broad application, an increase in SMEDI cases has been reported in the last few years in Europe. This increase is often associated with the new variant 27a or 27a-like strains that have become predominant in Europe . It has been suggested that the appearance of 27a over the last decades is the result of viral adaptation to vaccine pressure on a viral population circulating in a partially immune population. Even though constant monitoring of PPV1 using molecular epidemiological approaches is of pivotal importance, viral sequence data are scarce especially in low-income countries. To fill this gap, a collection of 71 partial VP2 sequences originating from eight African countries during the period 2011–2021. The observed pattern largely reflected what has been observed in high-income regions, i.e., 27a-like strains were more frequently detected than less virulent NADL-8-like strains. A phylogeographic analysis supported this observation, highlighting that the African scenario has been largely shaped by multiple PPV1 importation events from other continents, especially Europe and Asia. The existence of such an international movement coupled with the circulation of potential vaccine-escape variants requires the careful evaluation of the control strategies to prevent new strain introduction and persistence.