PONE-D-23-01471Susceptibility and infectiousness of SARS-CoV-2 in children versus adults, by variant (wild-type, Alpha, Delta): a systematic review and meta-analysis of household contact studiesPLOS ONE

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Editor Comments:

Although the Alpha and Delta variants are no longer circulating today, your analysis is of interest as it provides insight into the impact that SARS-CoV-2 has had on its evolution. Throughout the pandemic, the pediatric population has been of particular interest to the medical world due to the response that children have had to the infection. The data you present is of interest and worth publishing.

I recommend a revision of the text to update it, given that it was written in 2022.

The introduction should be changed without reference to the number of cases and deaths.

Review the discussion on Omicron and the limitations part where it makes mention of Omicron.

Reviewers' comments:

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Reviewer #1: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: The authors have performed a a systematic reivew of susceptiblity and infectiousness of SARS-CoV-2 in children versus adults by variant type - wild type, alpha and delta.

The authors defined "household", "index/primary case", "household contact" NB acronym hhc should be capitalised.

Why should vaccinated individuals be excluded as a contact? Very relevant in delta (and more recent variants); and useful to understand the differences in susceptiblity in vaccinated versus unvaccinated individuals.

The authors mention that a large proportion of studies were from China and the USA, but would recommend mentioning whether all studies were performed in high-moderate income countries. As this is a systematic review, the authors are behest to the quality of the studies. That said, it is important for the reader to understand and would recommend the authors to comment on 1. average household size, 2. guidance on isolation away from household members (or note it as a limitation if unknown) as this will affect both susceptibility and infectiousness.

The authors mention that the search was conducted up to and including January 2022, and therefore only 1 delta household study has been included. I think the authors should acknowledge that further studies have been published, in other settings to better inform HH transmission of the delta variant.

Variants are not usually capitalised (e.g. should read alpha, delta, omicron etc)

Page 16 - consider revising "After the omicron such studies have..." (remove 'the')

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Reviewer #1: No

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Susceptibility and infectiousness of SARS-CoV-2 in children versus adults, by variant (wild-type, alpha, delta): a systematic review and meta-analysis of household contact studies

PONE-D-23-01471R1

Dear Dr. Uthman,

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Kind regards,

Victor Daniel Miron

Academic Editor

PLOS ONE