Responses to SARS-CoV-2 Vaccination in Patients with Cancer (ReCOVer Study): A Prospective Cohort Study of the Hellenic Cooperative Oncology Group.

Data on the effectiveness and safety of approved SARS-CoV-2 vaccines in cancer patients are limited. This observational, prospective cohort study investigated the humoral immune response to SARS-CoV-2 vaccination in 232 cancer patients from 12 HeCOG-affiliated oncology departments compared to 100 healthcare volunteers without known active cancer. The seropositivity rate was measured 2-4 weeks after two vaccine doses, by evaluating neutralising antibodies against the SARS-CoV-2 spike protein using a commercially available immunoassay. Seropositivity was defined as ≥33.8 Binding-Antibody-Units (BAU)/mL. A total of 189 patients and 99 controls were eligible for this analysis. Among patients, 171 (90.5%) were seropositive after two vaccine doses, compared to 98% of controls (p = 0.015). Most seronegative patients were males (66.7%), >70-years-old (55.5%), with comorbidities (61.1%), and on active treatment (88.9%). The median antibody titers among patients were significantly lower than those of the controls (523 vs. 2050 BAU/mL; p < 0.001). The rate of protective titers was 54.5% in patients vs. 97% in controls (p < 0.001). Seropositivity rates and IgG titers in controls did not differ for any studied factor. In cancer patients, higher antibody titers were observed in never-smokers (p = 0.006), women (p = 0.022), <50-year-olds (p = 0.004), PS 0 (p = 0.029), and in breast or ovarian vs. other cancers. Adverse events were comparable to registration trials. In this cohort study, although the seropositivity rate after two vaccine doses in cancer patients seemed satisfactory, their antibody titers were significantly lower than in controls. Monitoring of responses and further elucidation of the clinical factors that affect immunity could guide adaptations of vaccine strategies for vulnerable subgroups.

Environmental testing for SARS-CoV-2 in three tertiary-care hospitals during the peak of the third COVID-19 wave.

Contamination of surfaces has been implicated in transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We tested by real-time PCR for SARS-CoV-2 contamination environmental samples from three hospitals during the peak of the third pandemic wave. Overall, 19 of 463 (4.1%) samples tested positive: 12 of 173 (6.9%) samples from a COVID-19 hospital, 3 of 177 (1.7%) samples from a non-COVID-19 hospital, and 4 of 113 (3.5%) samples from a pediatric hospital with dedicated COVID-19 clinics. Most positive samples originated from emergency departments (EDs) (47.3%) and the intensive care units (ICUs) (26.3%) of the COVID-19 hospital. Positive samples belonged almost exclusively (18/19) to the highly transmissible B.1.1.7 cluster, that might explain environmental contamination at this stage of the pandemic. The frequency and efficiency of disinfection in high-risk patient areas, such as EDs and ICUs, should be reinforced, especially during this period where highly transmissible variants of concern are widespread.

Molecular Epidemiology of SARS-CoV-2 in Greece Reveals Low Rates of Onward Virus Transmission after Lifting of Travel Restrictions Based on Risk Assessment during Summer 2020.

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 estimate 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.

Transmission dynamics of SARS-CoV-2 within families with children in Greece: A study of 23 clusters.

There is limited information on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection clustering within families with children. We aimed to study the transmission dynamics of SARS-CoV-2 within families with children in Greece. We studied 23 family clusters of coronavirus disease 2019 (COVID-19). Infection was diagnosed by reverse-transcriptase polymerase chain reaction in respiratory specimens. The level of viral load was categorized as high, moderate, or low based on the cycle threshold values. There were 109 household members (66 adults and 43 children). The median attack rate per cluster was 60% (range: 33.4%-100%). An adult member with COVID-19 was the first case in 21 (91.3%) clusters. Transmission of infection occurred from an adult to a child in 19 clusters and/or from an adult to another adult in 12 clusters. There was no evidence of child-to-adult or child-to-child transmission. In total 68 household members (62.4%) tested positive. Children were more likely to have an asymptomatic SARS-CoV-2 infection compared to adults (40% vs 10.5%; P = .021). In contrast, adults were more likely to develop a severe clinical course compared with children (8.8% vs 0%; P = .021). In addition, infected children were significantly more likely to have a low viral load while adults were more likely to have a moderate viral load (40.7% and 18.6% vs 13.8% and 51.7%, respectively; P = .016). In conclusion, while children become infected by SARS-CoV-2, they do not appear to transmit infection to others. Furthermore, children more frequently have an asymptomatic or mild course compared to adults. Further studies are needed to elucidate the role of viral load on these findings.

A main event and multiple introductions of SARS-CoV-2 initiated the COVID-19 epidemic in Greece.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic. Chains of infections starting from various countries worldwide seeded the outbreak of COVID-19 in Athens, capital city of Greece. A full-genome analysis of isolates from Athens' hospitals and other healthcare providers revealed the variety of SARS-CoV-2 that initiated the pandemic before lockdown and passenger flight restrictions. A dominant variant, encompassing the G614D amino acid substitution, spread through a major virus dispersal event, and sporadic introductions of rare variants characterized the local initiation of the epidemic. Mutations within the genome highlighted the genetic drift of the virus as rare variants emerged. An important variant contained a premature stop codon in orf7a leading to the truncation of a possibly important for viral pathogenesis domain. This study may serve as a reference for resolving future lines of infection in the area, especially after resumption of passenger flight connections to Athens and Greece during summer of 2020.

Association Between Upper Respiratory Tract Viral Load, Comorbidities, Disease Severity, and Outcome of Patients With SARS-CoV-2 Infection.

BACKGROUND: There is limited information on the association between upper respiratory tract (URT) viral loads, host factors, and disease severity in SARS-CoV-2-infected patients. METHODS: We studied 1122 patients (mean age, 46 years) diagnosed by polymerase chain reaction (PCR). URT viral load, measured by PCR cycle threshold, was categorized as high, moderate, or low. RESULTS: There were 336 (29.9%) patients with comorbidities; 309 patients (27.5%) had high, 316 (28.2%) moderate, and 497 (44.3%) low viral load. In univariate analyses, compared to patients with moderate or low viral load, patients with high viral load were older, more often had comorbidities, developed Symptomatic disease (COVID-19), were intubated, and died. Patients with high viral load had longer stay in intensive care unit and longer intubation compared to patients with low viral load (P values < .05 for all comparisons). Patients with chronic cardiovascular disease, hypertension, chronic pulmonary disease, immunosuppression, obesity, and chronic neurological disease more often had high viral load (P value < .05 for all comparisons). In multivariate analysis high viral load was associated with COVID-19. Level of viral load was not associated with any other outcome. CONCLUSIONS: URT viral load could be used to identify patients at higher risk for morbidity or severe outcome.

In-flight transmission of COVID-19 on flights to Greece: An epidemiological analysis.

BACKGROUND: The emergence in China in late 2019 and subsequent progression of a pandemic of a respiratory disease named coronavirus disease 2019 (COVID-19) was highly facilitated by international travel. We present 5 cases of probable in-flight transmission in Greece. METHODS: We studied international passengers arriving to or departing from Greece from February 26 through March 9, 2020. Contact tracing extended up to 4 days before the onset of symptoms and focused on close contacts. Close contacts were defined as persons sitting within a distance of <2 m for >15 min, including passengers seated two seats around the index case and all crew members and persons who had close contact with the index case. RESULTS: We investigated 18 international flights with 2224 passengers and 110 crew members. Main countries of departure included Northern Italy, Israel and the United Kingdom. In accordance with the national surveillance investigation, in these flights there were 21 index cases and 891 contact traced cases. Six index cases were symptomatic during the flight. Of the 891 contact traced cases, 4 passengers and 1 crew member developed laboratory-confirmed infection (3 with COVID-19 and 2 with asymptomatic infection); they travelled on the same flight with two COVID-19 cases. CONCLUSIONS: Air travel has played a central role in the progression of the COVID-19 pandemic. However, there are scarce data about in-flight transmission. Our extensive investigation showed five cases of probable in-flight transmission. Efforts should be placed in order to ensure the prompt implementation of appropriate infection control measures on board.