Duration of viable virus shedding in SARS-CoV-2 omicron variant infection

Abstract

Clinical features of SARS-CoV-2 Omicron variant infection, including incubation period and transmission rates, distinguish this variant from preceding variants. However, whether the duration of shedding of viable virus differs between omicron and previous variants is not well understood. To characterize how variant and vaccination status impact shedding of viable virus, we serially sampled symptomatic outpatients newly diagnosed with COVID-19. Anterior nasal swabs were tested for viral load, sequencing, and viral culture. Time to PCR conversion was similar between individuals infected with the Delta and the Omicron variant. Time to culture conversion was also similar, with a median time to culture conversion of 6 days (interquartile range 4-8 days) in both groups. There were also no differences in time to PCR or culture conversion by vaccination status.

Viral dynamics of Omicron and Delta SARS-CoV-2 variants with implications for timing of release from isolation: a longitudinal cohort study

“…This is consistent with previous data showing no major differences in Omicron infection duration when compared to Delta 16 or time to culture or PCR conversion between the two variants. 15 Similar to the findings of Boucau et al 15 , we found no significant difference in culture or PCR conversion in boosted participants when compared to those who were fully vaccinated. This suggests that the population level protection provided by COVID-19 booster vaccination doses against Omicron 17,18 result from protection against infection rather than altered viral kinetics in vaccinated individuals causing reduced transmission or more rapid clearance.…”

“…14 Our results are similar to data from the National Basketball Association cohort which found 40% with cycle thresholds of less than 30 at day 5, though this study did not examine culture positivity. 15…”

“…14 Our results are similar to data from the National Basketball Association cohort which found 40% with cycle thresholds of less than 30 at day 5, though this study did not examine culture positivity. 15 Whether we calculated days to culture clearance from date of diagnosis or from symptom onset led to differences on likelihood that individuals released from isolation were still infectious and how quickly some were released. Reliance on time from diagnosis for determining duration of isolation kept 41% of people in isolation longer than necessary (using culture conversion as a measure of non-infectiousness).…”

A simple algorithm based on initial Ct values predicts the duration to SARS-CoV-2 negativity and allows more efficient test-to-release and return-to-work schedules

“…Interestingly time to negativity or time to reaching a lower viral load (Ct>30) were very similar, when comparing data from the phases in the pandemic when alpha, delta or omicron were dominant. Previous data comparing the time to negative PCR in patients infected with omicron versus delta variant indicated also that there is no significant difference between the two groups 10 .…”

Virologic characterization of symptom rebound following nirmatrelvir-ritonavir treatment for COVID-19

“…The POSITIVES cohort is a longitudinal study of individuals with COVID-19 infection that aims to characterize virologic and immunologic aspects of infection [4][5][6]. To better understand the clinical phenomenon of symptom relapse after nirmatrelvir-ritonavir treatment, we selectively enrolled seven ambulatory individuals recently treated with nirmatrelvir-ritonavir with recurrent symptoms after initial resolution.…”