Περίληψη:
The novel coronavirus severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) spread rapidly during the first months of 2020 and
continues to expand in multiple areas across the globe. Molecular
epidemiology has provided an added value to traditional public health
tools by identifying SARS-CoV-2 clusters or providing evidence that
clusters based on virus sequences and contact tracing are highly
concordant. Our aim was to infer the levels of virus importation and to
esti-mate the impact of public health measures related to travel
restrictions to local transmission in Greece. Our phylogenetic and
phylogeographic analyses included 389 full-genome SARS-CoV-2 sequences
collected during the first 7 months of the pandemic in Greece and a
random collection in five replicates of 3,000 sequences sampled
globally, as well as the best hits to our data set identified by BLAST.
Phylogenetic trees were reconstructed by the maximum likelihood method,
and the putative source of SARS-CoV-2 infections was inferred by
phylogeographic analysis. Phylogenetic analyses revealed the presence of
89 genetically distinct viruses identified as independent introductions
into Greece. The proportion of imported strains was 41%, 11.5%, and
8.8% during the three periods of sampling, namely, March (no travel
restrictions), April to June (strict travel restrictions), and July to
September (lifting of travel restrictions based on thorough risk
assessment), respectively. The results of phylogeographic analysis were
confirmed by a Bayesian approach. Our findings reveal low levels of
onward transmission from imported cases during summer and underscore the
importance of targeted public health measures that can increase the
safety of international travel during a pandemic.
IMPORTANCE Our study based on current state-of-the-art molecular
epidemiology methods suggests that virus screening and public health
measures after the lifting of travel restrictions prevented SARS-CoV-2
onward transmission from imported cases during summer 2020 in Greece.
These findings provide important data on the efficacy of targeted public
health measures and have important implications regarding the safety of
international travel during a pandemic. Our results can provide a
roadmap about prevention policy in the future regarding the reopening of
borders in the presence of differences in vaccination coverage, the
circulation of the virus, and the presence of newly emergent variants
across the globe.
Συγγραφείς:
Kostaki, Evangelia Georgia
Pavlopoulos, Georgios A.
Verrou,
Kleio-Maria
Ampatziadis-Michailidis, Giannis
Harokopos, Vaggelis
and Hatzis, Pantelis
Moulos, Panagiotis
Siafakas, Nikolaos and
Pournaras, Spyridon
Hadjichristodoulou, Christos
Chatzopoulou,
Fani
Chatzidimitriou, Dimitrios
Panagopoulos, Periklis and
Lourida, Panagiota
Argyraki, Aikaterini
Lytras, Theodoros and
Sapounas, Spyros
Gerolymatos, Gerasimos
Panagiotakopoulos,
Georgios
Prezerakos, Panagiotis
Tsiodras, Sotirios
Sypsa,
Vana
Hatzakis, Angelos
Anastassopoulou, Cleo
Spanakis,
Nikolaos
Tsakris, Athanasios
Dimopoulos, Meletios Athanasios and
Kotanidou, Anastasia
Sfikakis, Petros
Kollias, Georgios and
Magiorkinis, Gkikas
Paraskevis, Dimitrios
