key: cord-0986240-hux4oas6
authors: Costa, Rosa; Bueno, Felipe; Giménez, Estela; Bracho, Alma; Albert, Eliseo; Carretero, Diego; de Michelena, Paula; Martínez-Costa, Cecilia; González-Candelas, Fernando; Navarro, David
title: Initial viral load and decay kinetics of SARS-CoV-2 lineage B.1.1.7 in the upper respiratory tract of adults and children
date: 2021-08-11
journal: J Infect
DOI: 10.1016/j.jinf.2021.08.015
sha: 64989ec769d775d1e511a9b8b24ee0d7bb57235c
doc_id: 986240
cord_uid: hux4oas6

nan

We read with interest the systematic review published by Walsh et al. in the Journal of Infection [1] , focusing on the dynamics of SARS-CoV-2 RNA at the upper respiratory tract (URT). In this context, a novel SARS-CoV-2 variant lineage (B.1.1.7), first detected in the UK at the end of 2020 has transmission advantage over other lineages [2] . Increased transmissibility of the B.1.1.7 variant has been linked to enhanced ACE2 affinity [3] allegedly resulting in higher viral loads in URT, an observation that has been reported in some [3] [4] [5] [6] , but not all [7] large series published to date. In addition, longer duration of SARS-CoV-2 RNA shedding in URT has been reported in individuals infected by the B.1.1.7 variant as compared to controls [8] ; if proven, this may have important implications regarding isolation policies. The current retrospective, observational study was undertaken to gain further insight into the above issues. It included a convenience sample of 990 individuals (799 aged >18 years; 507 females) testing positive for SARS-CoV-2 RNA in nasopharyngeal specimens (NP) by the in the control group, with no differences between children and adults. As for asymptomatic individuals (140 infected by the B.1.1.7 variant), RT-PCR testing was performed within the first 10 days since diagnosis (for household) or contact with (for non-household) the index case in individuals from both groups. A total of 1,152 NP specimens (median 1 specimen/patient; range, 1-3) were included in the analyses described below.

We found that SARS-CoV-2 B.1.1.7-infected individuals displayed initial NP viral loads around 1 log 10 higher than controls (median, 7.6 log 10 copies/ml; range, 3.3-12.1 vs. 6.8 log 10 copies/ml; range, 2.4-13.1; P<0.001), a figure that concurs remarkably with that observed by Jones et al. [4] , and overall support previous observations [3] [4] [5] [6] reported in studies involving large cohorts, that were nevertheless poorly defined regarding subject age, individual clinical condition at diagnosis, timing of URT specimen collection or all of the above. A subanalysis including only SARS-CoV-2 B.1.1.7-infected individuals as confirmed by whole-genome sequencing (n=108) yielded comparable results (P<0.001) (not shown). A novel observation was that the difference in viral load between B.1.1.7 and non-B.1.1.7 infected individuals remained significant (P<0.001) for adults ( Figure 1B ), but not for children (P=0.41) ( Figure 1C ). When symptomatic patients infected by either the B.1.1.7 or other variants were analyzed separately, initial viral loads were also higher (P=0.04) for adults ( Figure 1D ), but again not (P=0.16) for children ( Figure 1E ), although a trend towards higher viral loads was noticeable in B.1.1.7 infected subjects. We hypothesize that a more robust early innate immune response to SARS-CoV-2 in children as compared to adults may minimize the apparent replicative advantage of the B.1.1.7 variant over other less transmissible ones [9] . Likewise, Asymptomatic adults infected by the B.1.1.7 variant had higher initial SARS-CoV-2 RNA loads (P=0.02) than controls ( Figure 1F ).

It is of interest that SARS-CoV-2 RNA loads measured in the comparison groups were unlikely to be biased by differences in cellularity across NP specimens, as determined by amplification of the βglucuronidase housekeeping gene by RT-PCR [10] 

This work received no public or private funds.

The authors declare no conflicts of interest. 

SARS-CoV-2 detection, viral load and infectivity over the course of an infection

Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England

SARS-CoV-2 B.1.1.7 and B.1.351 spike variants bind human ACE2 with increased affinity

Estimating infectiousness throughout SARS-CoV-2 infection course

S-Variant SARS-CoV-2 Lineage B1.1.7 Is Associated With Significantly Higher Viral Load in Samples Tested by TaqPath Polymerase Chain Reaction

Virological and serological characterization of critically ill patients with COVID-19 in the UK: Interactions of viral load, antibody status and B.1.1.7 variant infection

Increased infections, but not viral burden, with a new SARS-CoV-2 variant

Infection sustained by lineage B.1.1.7 of SARS-CoV-2 is characterised by longer persistence and higher viral RNA loads in nasopharyngeal swabs

Immune responses to SARS-CoV-2 in three children of parents with symptomatic COVID-19

Amplification of human β-glucuronidase gene for appraising the accuracy of negative SARS-CoV-2 RT-PCR results in upper respiratory tract specimens