medRxiv.  2021  Mar  08.  pii:  2021.03.07.21253094. [Epub  ahead  of  print]
Kathryn J Gray, 
Evan A Bordt, 
Caroline Atyeo, 
Elizabeth Deriso, 
Babatunde Akinwunmi, 
Nicola Young, 
Aranxta Medina Baez, 
Lydia L Shook, 
Dana Cvrk, 
Kaitlyn James, 
Rose M De Guzman, 
Sara Brigida, 
Khady Diouf, 
Ilona Goldfarb, 
Lisa M Bebell, 
Lael M Yonker, 
Alessio Fasano, 
Sayed A Rabi, 
Michal A Elovitz, 
Galit Alter, 
Andrea G Edlow.
 
  
Background: Pregnant and lactating women were excluded from initial COVID-19 vaccine trials; thus, data to guide vaccine decision-making are lacking. We sought to evaluate the immunogenicity and reactogenicity of COVID-19 mRNA vaccination in pregnant and lactating women.
Methods: 131 reproductive-age vaccine recipients (84 pregnant, 31 lactating, and 16 non-pregnant) were enrolled in a prospective cohort study at two academic medical centers. Titers of SARS-CoV-2 Spike and RBD IgG, IgA and IgM were quantified in participant sera (N=131), umbilical cord sera (N=10), and breastmilk (N=31) at baseline, 2nd vaccine dose, 2-6 weeks post 2nd vaccine, and delivery by Luminex, and confirmed by ELISA. Titers were compared to pregnant women 4-12 weeks from native infection (N=37). Post-vaccination symptoms were assessed. Kruskal-Wallis tests and a mixed effects model, with correction for multiple comparisons, were used to assess differences between groups.
Results: Vaccine-induced immune responses were equivalent in pregnant and lactating vs non-pregnant women. All titers were higher than those induced by SARS-CoV-2 infection during pregnancy. Vaccine-generated antibodies were present in all umbilical cord blood and breastmilk samples. SARS-CoV-2 specific IgG, but not IgA, increased in maternal blood and breastmilk with vaccine boost. No differences were noted in reactogenicity across the groups.
Conclusions: COVID-19 mRNA vaccines generated robust humoral immunity in pregnant and lactating women, with immunogenicity and reactogenicity similar to that observed in non-pregnant women. Vaccine-induced immune responses were significantly greater than the response to natural infection. Immune transfer to neonates occurred via placental and breastmilk.