Duration of SARS-CoV-2 shedding: A systematic review.

Background: Positive viral severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cultures indicate shedding of infectious virus and corresponding transmission risk of coronavirus disease 2019 (COVID-19). The research question of this systematic review was: Is there a discernible pattern in the timing of SARS-CoV-2 virus isolation, and what is the proportion of positive and negative results for isolation of SARS-CoV-2 virus with viral culture relative to the onset of clinical symptoms or the day of diagnosis, as indicated by longitudinal studies? Methods: We systematically searched PubMed and Embase from inception to 16 February 2023 for English-language studies with serial viral culture testing within symptomatic or asymptomatic SARS-CoV-2 infected persons during the post-vaccination period. Outcomes of interest were the daily culture status per study and the overall daily culture positivity rate of SARS-CoV-2. We critically appraised the selected studies using the Newcastle-Ottawa quality assessment scale. Results: We included 14 viral shedding studies in this systematic review. Positive viral SARS-CoV-2 cultures were detected in samples ranging from 4 days before to 18 days after symptom onset. The daily culture SARS-CoV-2 positivity rate since symptom onset or diagnosis showed a steep decline between day 5 and 9, starting with a peak ranging from 44% to 50% on days -1 to 5, decreasing to 28% on day 7 and 11% on day 9, and finally ranging between 0% and 8% on days 10-17. Conclusions: Viral shedding peaked within 5 days since symptom onset or diagnosis and the culture positivity rate rapidly declined hereafter. This systematic review provides an overview of current evidence on the daily SARS-CoV-2 culture positivity rates during the post-vaccination period. These findings could be used to estimate the effectiveness of public health control measures, including treatment and preventive strategies, to reduce the spread of COVID-19.

Hybrid Immunity to SARS-CoV-2 from Infection and Vaccination-Evidence Synthesis and Implications for New COVID-19 Vaccines.

COVID-19 has taken a severe toll on the global population through infections, hospitalizations, and deaths. Elucidating SARS-CoV-2 infection-derived immunity has led to the development of multiple effective COVID-19 vaccines and their implementation into mass-vaccination programs worldwide. After ~3 years, a substantial proportion of the human population possesses immunity from infection and/or vaccination. With waning immune protection over time against emerging SARS-CoV-2 variants, it is essential to understand the duration of protection, breadth of coverage, and effects on reinfection. This targeted review summarizes available research literature on SARS-CoV-2 infection-derived, vaccination-elicited, and hybrid immunity. Infection-derived immunity has shown 93-100% protection against severe COVID-19 outcomes for up to 8 months, but reinfection is observed with some virus variants. Vaccination elicits high levels of neutralizing antibodies and a breadth of CD4+ and CD8+ T-cell responses. Hybrid immunity enables strong, broad responses, with high-quality memory B cells generated at 5- to 10-fold higher levels, versus infection or vaccination alone and protection against symptomatic disease lasting for 6-8 months. SARS-CoV-2 evolution into more transmissible and immunologically divergent variants has necessitated the updating of COVID-19 vaccines. To ensure continued protection against SARS-CoV-2 variants, regulators and vaccine technical committees recommend variant-specific or bivalent vaccines.

Enterococcus spp. and S. aureus colonization in neutropenic febrile children with cancer.

INTRODUCTION: Febrile neutropenia is one of the most serious treatment-related complications in cancer patients. Susceptible to rapidly progressing infections, which result in prolonged hospitalization and use of broad-spectrum antibiotics, neutropenic patients are subject to colonization by multiresistant agents, which enhances the risk of infections. METHODS: In this study we included samples collected with nasal, oropharyngeal and anal swabs from hospitalized children with febrile neutropenia following chemotherapy, between March 2014 and 2015, aiming to elucidate colonization by S. aureus and Enterococcus spp., as well as their resistance profile. RESULTS: S. aureus was found in 22% of the patients and 14% of the events. Methicillin-resistant S. aureus colonized 13.6% of patients. Including anal swabs in the screening increased the identification of colonized patients by 20%. Enterococcus spp. was found in 27% of patients and 17% of episodes. Enterococcal isolates resistant to vancomycin, accounting for 25% of the total, were not isolated in anal swabs at any time, with the oropharyngeal site being much more important. The rate of infection by Enterococcus spp. was 4.5% of all patients and 16% among the colonized patients. CONCLUSION: Especially in this population, colonization studies including more sites can yield a higher chance of positive results. Establishing the colonization profile in febrile neutropenic children following chemotherapy may help to institute an empirical antibiotic treatment aimed at antibiotic adequacy and lower induction of resistance, thereby decreasing the risk of an unfavorable clinical outcome.