Author:
Dzieciolowska Stefka,Charest Hugues,Roy Tonya,Fafard Judith,Carazo Sara,Levade Ines,Longtin Jean,Parkes Leighanne,Beaulac Sylvie Nancy,Villeneuve Jasmin,Savard Patrice,Corbeil Jacques,Serres Gaston De,Longtin Yves
Abstract
AbstractBackgroundThere is a need to understand the duration of infectivity of primary and recurrent COVID-19 and identify predictors of loss of infectivity.MethodsProspective observational cohort study with serial viral culture, rapid antigen detection test (RADT) and RT-PCR on nasopharyngeal specimens of healthcare workers with COVID-19. The primary outcome was viral culture positivity as indicative of infectivity. Predictors of loss of infectivity were determined using multivariate regression model. The performance of the US CDC criteria (fever resolution, symptom improvement and negative RADT) to predict loss of infectivity was also investigated.Results121 participants (91 female [79.3%]; average age, 40 years) were enrolled. Most (n=107, 88.4%) had received ≥3 SARS-CoV-2 vaccine doses, and 20 (16.5%) had COVID-19 previously. Viral culture positivity decreased from 71.9% (87/121) on day 5 of infection to 18.2% (22/121) on day 10. Participants with recurrent COVID-19 had a lower likelihood of infectivity than those with primary COVID-19 at each follow-up (day 5 OR, 0.14; p<0.001]; day 7 OR, 0.04; p=0.003]) and were all non-infective by day 10 (p=0.02). Independent predictors of infectivity included prior COVID-19 (adjusted OR [aOR] on day 5, 0.005; p=0.003), a RT-PCR Ct value <23 (aOR on day 5, 22.75; p<0.001), but not symptom improvement or RADT result.The CDC criteria would identify 36% (24/67) of all non-infectious individuals on Day 7. However, 17% (5/29) of those meeting all the criteria had a positive viral culture.ConclusionsInfectivity of recurrent COVID-19 is shorter than primary infections. Loss of infectivity algorithms could be optimized.
Publisher
Cold Spring Harbor Laboratory