Low-frequency variants in mildly symptomatic vaccine breakthrough infections presents a doubled-edged sword

The panzootic potential of SARS-CoV-2

Each year, SARS-CoV-2 is infecting an increasingly unprecedented number of species. In the present article, we combine mammalian phylogeny with the genetic characteristics of isolates found in mammals to elaborate on the host-range potential of SARS-CoV-2. Infections in nonhuman mammals mirror those of contemporary viral strains circulating in humans, although, in certain species, extensive viral circulation has led to unique genetic signatures. As in other recent studies, we found that the conservation of the ACE2 receptor cannot be considered the sole major determinant of susceptibility. However, we are able to identify major clades and families as candidates for increased surveillance. On the basis of our findings, we argue that the use of the term panzootic could be a more appropriate term than pandemic to describe the ongoing scenario. This term better captures the magnitude of the SARS-CoV-2 host range and would hopefully inspire inclusive policy actions, including systematic screenings, that could better support the management of this worldwide event.

COVID-19 Infection Risk Following Elective Arthroplasty and Surgical Complications in COVID-19 Vaccinated Patients: A Multicenter Comparative Cohort Study

Background

We aimed to determine symptomatic Coronavirus disease 2019 (COVID-19) rates within 1 month of elective arthroplasty for vaccinated individuals and to determine whether vaccination guarantees protection against COVID-19 after arthroplasty (primary outcome). In addition, the 90-day surgical complications were compared to those of an unvaccinated group (secondary outcome).

Methods

A prospective cohort study was conducted on elective joint arthroplasty patients at 3 tertiary hospitals in 2 major cities (Tehran and Isfahan) in our country (Iran). The outcomes of the COVID-19-vaccinated group were assessed between October 2021 and March 2022. Ninety-day surgical complications were compared with a historical cohort of unvaccinated patients treated earlier in the pandemic (April 2020-March 2021).

Results

The study included 1717 consecutive patients: 962 vaccinated and 755 unvaccinated. In the vaccinated group, 38 patients (3.9%) contracted COVID-19, 4 (10.5%) were hospitalized again, and none required intensive care unit admission. The multivariate logistic regression analysis revealed that COVID-19-positive cases are more likely to be female (odds ratio [OR] = 12.5), to have visitors to their home (OR = 4.7), and to stay longer in the hospital (OR = 1.2) than COVID-19-negative cases. Compared to unvaccinated patients, the postoperative COVID-19 rate was not significantly different (3.9% vs 2.4%, P = .07). The incidence of surgical complications was similar between the 2 groups (P > .05).

Conclusions

The vaccination does not provide a guarantee that a patient will not contract COVID-19 following their arthroplasty surgery, especially in a region with a high rate of COVID-19. We believe reasonable perioperative COVID-19 precautions may be warranted even in vaccinated patients.

Structural Evolution of Delta (B.1.617.2) and Omicron (BA.1) Spike Glycoproteins

The vast amount of epidemiologic and genomic data that were gathered as a global response to the COVID-19 pandemic that was caused by SARS-CoV-2 offer a unique opportunity to shed light on the structural evolution of coronaviruses and in particular on the spike (S) glycoprotein, which mediates virus entry into the host cell by binding to the human ACE2 receptor. Herein, we carry out an investigation into the dynamic properties of the S glycoprotein, focusing on the much more transmissible Delta and Omicron variants. Notwithstanding the great number of mutations that have accumulated, particularly in the Omicron S glycoprotein, our data clearly showed the conservation of some structural and dynamic elements, such as the global motion of the receptor binding domain (RBD). However, our studies also revealed structural and dynamic alterations that were concentrated in the aa 627–635 region, on a small region of the receptor binding motif (aa 483–485), and the so-called “fusion-peptide proximal region”. In particular, these last two S regions are known to be involved in the human receptor ACE2 recognition and membrane fusion. Our structural evidence, therefore, is likely involved in the observed different transmissibility of these S mutants. Finally, we highlighted the role of glycans in the increased RBD flexibility of the monomer in the up conformation of Omicron.

Low-frequency variants in mildly symptomatic vaccine breakthrough infections presents a doubled-edged sword

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC) has raised questions regarding vaccine protection against SARS-CoV-2 infection, transmission, and ongoing virus evolution. Twenty-three mildly symptomatic "vaccination breakthrough" infections were identified as early as January 2021 in Alachua County, Florida, among individuals fully vaccinated with either the BNT162b2 (Pfizer) or the Ad26 (Janssen/J&J) vaccines. SARS-CoV-2 genomes were successfully generated for 11 of the vaccine breakthroughs, and 878 individuals in the surrounding area and were included for reference-based phylogenetic investigation. These 11 individuals were characterized by infection with VOCs, but also low-frequency variants present within the surrounding population. Low-frequency mutations were observed, which have been more recently identified as mutations of interest owing to their location within targeted immune epitopes (P812L) and association with increased replicative capacity (L18F). We present these results to posit the nature of the efficacy of vaccines in reducing symptoms as both a blessing and a curse-as vaccination becomes more widespread and self-motivated testing reduced owing to the absence of severe symptoms, we face the challenge of early recognition of novel mutations of potential concern. This case study highlights the critical need for continued testing and monitoring of infection and transmission among individuals regardless of vaccination status.