Review 1: "Maternal Antibody Response and Transplacental Transfer Following SARS-CoV-2 Infection or Vaccination in Pregnancy"

RR:C19 Evidence Scale rating by reviewer:

• Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.

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Review:

Abstract:

• Overall well written and succinct

• Within the results, it is unclear to me what type of vaccines patients received, assuming majority mRNA? Also, the results should include vaccinated cord blood transfer ratios.

Introduction

• To line: “COVID-19 vaccines include messenger RNA (mRNA) vaccines BNT162b2(Pfizer/BioNTech) and mRNA-1273 (Moderna) and viral vector vaccines such as J&J/Janssen.” The authors should specify the CDC's preference for mRNA vaccines.

•  “Yet, few studies have addressed the duration of vaccine-induced antibody response in pregnancy or have compared vaccine-induced antibodies to natural infection in pregnancy.” This line should include proper citations of relevant studies.

•  Again, it is unclear what type of vaccines the authors are analyzing, and I suggest changing the introduction.

  Methods

• Within the section on Maternal and infant antibodies, the last line says “antibody ratio calculated as infant divided by maternal.” Instead of infant, the authors should say cord. Similarly elsewhere in the text and in figures, the authors should specify “cord” rather than “infant.”

• Could authors clarify IRB approval vs exempt vs..?

• There is great analytic method to differentiate the severity of infection from latency from infection to delivery as they often occur together and are difficult to tease out

  Results

• The racial differences in vaccination versus infection are striking.

• Figures 1 -4 would benefit from the succinct explanation of the methods and main findings.

  Discussion

• The authors note “The possibility that fetal sex modifies maternal antibody response or placental transfer is intriguing this is more than intriguing and has been well studied in the literature.” I would like to see the authors discuss their findings in the context of the sex differences in vaccine-induced immunity. The authors can reference PMID30547182 (Fischinger S, Semin Immunopathol, 2019).

• Another limitation is that the manuscript did not analyze or present data on the crossover (ie how many vaccinated patients also had an infection), and should specify cord blood as a marker for neonatal levels but that correlates of protection have not been established.