Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 May 4;26(6):106802.
doi: 10.1016/j.isci.2023.106802. eCollection 2023 Jun 16.

Assessment of SARS-CoV-2 neutralizing antibody titers in breastmilk from convalescent and vaccinated mothers

Christine Bäuerl  1 , Joao Zulaica  2 , Luciana Rusu  2 , Alicia Rodríguez Moreno  2 , Francisco J Pérez-Cano  3 , Carles Lerin  4   5 , Desirée Mena-Tudela  6 , Laia Aguilar-Camprubí  7 , Anna Parra-Llorca  8 , Cecilia Martínez-Costa  9 , Ron Geller  2 , Maria Carmen Collado  1 ; MilkCORONA study team
Affiliations

Assessment of SARS-CoV-2 neutralizing antibody titers in breastmilk from convalescent and vaccinated mothers

Christine Bäuerl et al. iScience. .

Abstract

Breastmilk contains antibodies that could protect breastfed infants from infections. In this work, we examined if antibodies in breastmilk could neutralize SARS-CoV-2 in 84 breastmilk samples from women that were either vaccinated (Comirnaty, mRNA-1273, or ChAdOx1), infected with SARS-CoV-2, or both infected and vaccinated. The neutralization capacity of these sera was tested using pseudotyped vesicular stomatitis virus carrying either the Wuhan-Hu-1, Delta, or BA.1 Omicron spike proteins. We found that natural infection resulted in higher neutralizing titers and that neutralization correlated positively with levels of immunoglobulin A in breastmilk. In addition, significant differences in the capacity to produce neutralizing antibodies were observed between both mRNA-based vaccines and the adenovirus-vectored ChAdOx1 COVID-19 vaccine. Overall, our results indicate that breastmilk from naturally infected women or those vaccinated with mRNA-based vaccines contains SARS-CoV-2 neutralizing antibodies that could potentially provide protection to breastfed infants from infection.

Keywords: Health sciences; Immune response; Public health; Virology.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

None
Graphical abstract
Figure 1
Figure 1
Frequency distribution of neutralizing antibody titers against Wuhan-Hu-1, Delta, and Omicron BA.1 S variants in breastmilk samples from convalescent mothers (A) Breastmilk samples from mothers infected during March to May 2020 (Wuhan-Hu-1 wave). (B) Breastmilk samples from mothers infected during January to mid-February 2022 (Omicron wave). Fisher’s exact test was used to assess statistical significance. Numbers in the bars indicate the number of samples with detectable NtAb/total number of each group.
Figure 2
Figure 2
Virus-specific-RBD antibody endpoint titers in breastmilk samples from convalescent mothers infected with SARS-CoV-2 during Wuhan-Hu-1 wave and the first Omicron BA.1 wave (A) RBD-IgA Endpoint titer. (B) RBD-IgG Endpoint titer. Mann-Whitney test was used to assess for statistical significance. Box-plots show the median (horizontal line inside box), interquartile range (box), and whiskers depict the minimum and maximum value. Endpoint titers above 1 are considered positive for SARS-CoV-2-specific RBD-IgG and IgA.
Figure 3
Figure 3
ChAdOx1 fails to induce neutralizing antibodies in breastmilk (A) Neutralizing antibody titer (reciprocal IC50) against SARS-CoV-2 ancestral Wuhan-Hu-1 S variant in breastmilk samples of ChAdOx1, mRNA-1273, and Comirnaty-vaccinated lactating mothers at seven days after the second dose. (B) Neutralizing antibody titer (reciprocal IC50) against SARS-CoV-2 ancestral Wuhan-Hu-1 S variant in breastmilk samples of vaccinated lactating mothers compared to convalescent mothers infected during the Wuhan-Hu-1 wave in 2020 (March to May 2020) and during Omicron BA.1 wave (January to mid-February 2022). ∗ Statistical significance to the vaccinated group was calculated with all data from the different vaccine types. Kruskal-Wallis test followed by a Dunn’s multiple comparison test was used to assess for statistical significance. Box-plots show the median (horizontal line inside box), interquartile range (box), and whiskers depict the minimum and maximum value.
Figure 4
Figure 4
NtAb titers against the ancestral SARS-CoV-2 Wuhan-Hu-1 S variant correlate with RBD-specific antibodies in breastmilk from vaccinated mothers Spearman’s correlation analysis between NtAb titers (reciprocal IC50) against the SARS-CoV-2 Wuhan-Hu-1 variant and virus-specific-RBD antibody titers were performed for: (A) RBD-IgA Endpoint titer. (B) RBD-IgG Endpoint titer. Data from different vaccine types were grouped due to the small dataset (n = 16 in each vaccine group: ChAdOx1, mRNA-1273, and Cormirnaty); individual correlations for vaccines are shown in Figure S4.
Figure 5
Figure 5
SARS-CoV-2 infection before vaccination results in higher neutralizing activity against ancestral Wuhan-Hu-1 variant in breastmilk Breastmilk samples from mothers with a past COVID-19 infection and vaccinated with one dose (COVID-19 + D1; n = 5), and mothers vaccinated with two (n = 16) and three doses (n = 10) of Comirnaty vaccine were analyzed for: (A) RBD-IgA Endpoint titer. (B) RBD-IgG Endpoint titer. (C) NtAb titers (reciprocal IC50) against SARS-CoV-2 Wuhan-Hu-1 variant. Kruskal-Wallis test followed by a Dunn’s multiple comparison test was used to assess for statistical significance. Box-plots show the median (horizontal line inside box), interquartile range (box), and whiskers depict the minimum and maximum value. Endpoint titers above 1 are considered positive for SARS-CoV-2-specific RBD-IgG and IgA.
See this image and copyright information in PMC

References

    1. Spatz D.L., Davanzo R., Müller J.A., Powell R., Rigourd V., Yates A., Geddes D.T., van Goudoever J.B., Bode L. Promoting and protecting human milk and breastfeeding in a COVID-19 world. Front. Pediatr. 2020;8:633700. doi: 10.3389/fped.2020.633700. - DOI - PMC - PubMed
    1. Yang X., Fox A., DeCarlo C., Norris C., Griffin S., Wedekind S., Flanagan J.M., Shenker N., Powell R.L. Comparative profiles of SARS-CoV-2 spike-specific human milk antibodies elicited by mRNA- and adenovirus-based COVID-19 vaccines. Breastfeed. Med. 2022;17:638–646. doi: 10.1089/bfm.2022.0019. - DOI - PubMed
    1. Pace R.M., Williams J.E., Järvinen K.M., Belfort M.B., Pace C.D.W., Lackey K.A., Gogel A.C., Nguyen-Contant P., Kanagaiah P., Fitzgerald T., et al. Characterization of SARS-CoV-2 RNA, antibodies, and neutralizing capacity in milk produced by women with COVID-19. mBio. 2021;12 doi: 10.1128/mBio.03192-20. - DOI - PMC - PubMed
    1. Peng S., Zhu H., Yang L., Cao L., Huang X., Dynes M., Narayan A., Xia J., Chen Y., Zhang P., et al. A study of breastfeeding practices, SARS-CoV-2 and its antibodies in the breast milk of mothers confirmed with COVID-19. Lancet Reg. Health. West. Pac. 2020;4:100045. doi: 10.1016/j.lanwpc.2020.100045. - DOI - PMC - PubMed
    1. Bäuerl C., Randazzo W., Sánchez G., Selma-Royo M., García Verdevio E., Martínez L., Parra-Llorca A., Lerin C., Fumadó V., Crovetto F., et al. SARS-CoV-2 RNA and antibody detection in breast milk from a prospective multicentre study in Spain. Arch. Dis. Child. Fetal Neonatal Ed. 2022;107:216–221. doi: 10.1136/archdischild-2021-322463. - DOI - PMC - PubMed

LinkOut - more resources