Shedding of infectious SARS-CoV-2 despite vaccination

Riemersma, Kasen K.; Haddock, Luis A; Wilson, Nancy A.; Minor, Nicholas R.; Eickhoff, Jens; Grogan, Brittany; Kita-Yarbro, Amanda; Halfmann, Peter; Segaloff, Hannah E; Kocharian, Anna; Florek, Kelsey; Westergaard, Ryan P.; Bateman, Allen C.; Jeppson, Gunnar E.; Kawaoka, Yoshihiro; O’Connor, David H.; Friedrich, Thomas C.; Grande, Katarina M

doi:10.1371/journal.ppat.1010876

Cited by 40 publications

(12 citation statements)

References 49 publications

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“…These figures have basically provided some evidence about the growing relevance of vaccinates as a possible source of transmission. Beyond the German data, other authors have highlighted that fully vaccinated people equally spread SARS-CoV-2 infection [ 108 ], showing viral loads similar to unvaccinated individuals. Similarly, the relative need for further checks of the spread of the infection in vaccinated and unvaccinated people was proposed by several authors [ 109 , 110 ].…”

Section: Resultsmentioning

confidence: 99%

SARS-CoV-2—The Role of Natural Immunity: A Narrative Review

Diani

Leonardi²,

Cavezzi

et al. 2022

JCM

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Background: Both natural immunity and vaccine-induced immunity to COVID-19 may be useful to reduce the mortality/morbidity of this disease, but still a lot of controversy exists. Aims: This narrative review analyzes the literature regarding these two immunitary processes and more specifically: (a) the duration of natural immunity; (b) cellular immunity; (c) cross-reactivity; (d) the duration of post-vaccination immune protection; (e) the probability of reinfection and its clinical manifestations in the recovered patients; (f) the comparisons between vaccinated and unvaccinated as to the possible reinfections; (g) the role of hybrid immunity; (h) the effectiveness of natural and vaccine-induced immunity against Omicron variant; (i) the comparative incidence of adverse effects after vaccination in recovered individuals vs. COVID-19-naïve subjects. Material and Methods: through multiple search engines we investigated COVID-19 literature related to the aims of the review, published since April 2020 through July 2022, including also the previous articles pertinent to the investigated topics. Results: nearly 900 studies were collected, and 246 pertinent articles were included. It was highlighted that the vast majority of the individuals after suffering from COVID-19 develop a natural immunity both of cell-mediated and humoral type, which is effective over time and provides protection against both reinfection and serious illness. Vaccine-induced immunity was shown to decay faster than natural immunity. In general, the severity of the symptoms of reinfection is significantly lower than in the primary infection, with a lower degree of hospitalizations (0.06%) and an extremely low mortality. Conclusions: this extensive narrative review regarding a vast number of articles highlighted the valuable protection induced by the natural immunity after COVID-19, which seems comparable or superior to the one induced by anti-SARS-CoV-2 vaccination. Consequently, vaccination of the unvaccinated COVID-19-recovered subjects may not be indicated. Further research is needed in order to: (a) measure the durability of immunity over time; (b) evaluate both the impacts of Omicron BA.5 on vaccinated and healed subjects and the role of hybrid immunity.

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Section: Resultsmentioning

confidence: 99%

SARS-CoV-2—The Role of Natural Immunity: A Narrative Review

Diani

Leonardi²,

Cavezzi

et al. 2022

JCM

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“…As vaccines were made available using a tiering system based on age and at-risk status, most working age individuals would likely have received at least one dose by summer 2021 when environmental sampling positivity rates declined. Some studies suggest that vaccine status has no effect on viral titre and shedding by infected individuals (Boucau et al ., 2022; Riemersma et al ., 2022); however, other studies suggest that infectious viral titre and/or shedding duration is reduced in vaccinated individuals (Ke et al ., 2022; Plante et al ., 2022; Puhach et al ., 2022; Tian et al ., 2022). Additionally, a ferret model study found a significant reduction in viral titre in both nasal wash and oral swabs amongst animals vaccinated with only a primer dose of Astra-Zeneca vaccine 7 days after viral challenge (Marsh et al ., 2021).…”

Section: Discussionmentioning

confidence: 99%

Surface sampling for SARS-CoV-2 in workplace outbreak settings in the UK, 2021-22

Nicholls¹,

Spencer²,

Chen

et al. 2023

Preprint

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Aims: To utilise environmental surface sampling to evaluate areas of SARS-CoV-2 contamination within workplaces to identify trends and improve local COVID-control measures. Methods and Results: Surface sampling was undertaken at 12 workplaces that experienced a cluster of COVID-19 cases in the workforce between March 2021 and March 2022. 7.4% (61/829) of samples collected were positive for SARS-CoV-2 RNA by qPCR with only 1.8% (15/829) of samples identified with crossing threshold (Ct) values below 35.0. No sample returned whole genome sequence inferring RNA detected was degraded. Conclusions: Few workplace surface samples were positive for SARS-CoV-2 RNA and positive samples typically contained low levels of nucleic acid. Although these data may infer a low probability of fomite transmission or other forms of transmission within the workplace, Ct values may have been lower at the time of contamination. Workplace environmental sampling identified lapses in COVID-control measures within individual sites and showed trends through the pandemic. Significance and Impact of the Study: Prior to this study, few published reports investigated SARS-CoV-2 RNA contamination within workplaces experiencing cases of COVID-19. This report provides extensive data on environmental sampling identifying trends across workplaces and through the pandemic.

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“…According to reports, the prevalent delta variant can replicate roughly 1000 times more than its ancestors and exhibits immune-evasive characteristics. 229 According to current research, coronavirus antibodies made for the original strain (Wuhan strain) may only be half as potent as those made for the delta variation. 230 Even worse is that those who have the delta strain of the virus are shedding a lot more virus.…”

Section: Conclusion and Future Perspectivementioning

confidence: 92%