Breastfeeding Mother and Child Clinical Outcomes After COVID-19 Vaccination

  1. Jia Ming Low
  2. Le Ye Lee
  3. Yvonne Peng Mei Ng
  4. Youjia Zhong
  5. Zubair Amin

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Abstract

Pre-approval clinical trials of the Pfizer/BioNTech messenger RNA COVID-19 vaccine, BNT162b2 did not include participants who were breastfeeding. Therefore, there is limited evidence about outcomes of breastfeeding mother–child dyads and effects on breastfeeding after vaccination.

Research Aims:

To determine: (1) solicited adverse effects (e.g., axillary lymphadenopathy, mastitis, and breast engorgement), which are unique to lactating individuals; and (2) systemic and local adverse effects of COVID-19 mRNA vaccine on mothers and potential effects on their breastfed infants.

Method:

This was a prospective cohort study of lactating healthcare workers ( N = 88) in Singapore who received two doses of BNT162b2 vaccination (Pfizer/BioNTech). The outcomes of mother–child dyads within 28 days after the second vaccine dose were determined through a participant-completed questionnaire.

Results:

Minimal effects related to breastfeeding were reported by this cohort; three of 88 (3.4%) participants had mastitis, one (1.1%) participant experienced breast engorgement, five of 88 (5.7%) participants reported cervical or axillary lymphadenopathy. There was no change in human milk supply after vaccination. The most common side effect was pain/redness/swelling at the injection site, which was experienced by 57 (64.8%) participants. There were no serious adverse events of anaphylaxis or hospital admissions. There were no short-term adverse effects reported in the infants of 67 lactating participants who breastfed within 72 hr after BNT162b2 vaccination.

Conclusions:

BNT162b2 vaccination was well tolerated in lactating participants and was not associated with short-term adverse effects in their breastfed infants.

Study Protocol Registration:

The study protocol was registered at clinicaltrials.gov (NCT04802278).

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  1. Version published to 10.1177/08903344211056522
  2. ScreenIT

    SciScore for 10.1101/2021.06.19.21258892: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: This study was approved by the National Healthcare Group Institutional Review Board (Gestational Immunity For Transfer GIFT-2: DSRB Reference Number: 2021/00095).
    Consent: Informed consent was obtained from participants.
    Sex as a biological variableThis is a prospective cohort study of lactating women in Singapore who received two doses of BNT162b2 vaccination (Pfizer/BioNTech).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    This study was approved by the National Healthcare Group Institutional Review Board (Gestational Immunity For Transfer GIFT-2: DSRB Reference Number: 2021/00095).
    National Healthcare
    suggested: None

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study has expected limitations. The reported outcomes are subjective reports from study participants; for example, there was no quantification of milk supply post-vaccination with a relatively short follow-up duration. As with other self-reported questionnaire, there is a possibility of recall bias resulting in over- or underestimating the events reported. Lastly, vaccine related effects were elicited after the second dose but not for dose one.

    Results from TrialIdentifier: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT04802278RecruitingGestational Immunity for Transfer

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.06.19.21258892v1 on medRxiv