Table 1.

Immunogenicity measures in maternal blood or cord blood samples after COVID-19 vaccination during pregnancy^a

Location and study dates	Vaccines during pregnancy	Number of pregnant women vaccinated	Timing of vaccination during pregnancy	Comparator groups	Immune response measures	Responses in womenb	Responses in cord blood	Placental antibody transfer	Other results	Assays used for antibody quantification	Refs
Israel January–March 2021	At least one dose BNT162b2	86	First dose: 34.5 (±7.5) weeks GA	65 Women who had COVID-19 during pregnancy at 28.1 (±8.3) weeks GA 62 Unvaccinated uninfected pregnant women	Anti-RBD IgG and IgM; anti-S IgG and IgM Reported as net fluorescence intensity	Robust IgG response by day 15 after the first dose, further increase in IgG responses after the second dose At delivery, higher anti-S and anti-RBD IgG in vaccinated women than in infected women	IgG responses by day 15 after the first dose, further increase in IgG responses after second dose Anti-S and anti-RBD IgG no different between the vaccinated and infected groups IgM response in five samples from the infected group	Similar transfer profiles in the vaccinated and infected groups	Association between maternal and cord blood IgG responses	Milliplex MAP SARS-CoV-2 Antigen Panel, MerckMillipore	[30]
Israel January–February 2021	Two doses BNT162b2	96 Tested 2 months following the second dose	2–40 weeks GA	96 Non-pregnant vaccinated women	Anti-RBD IgG Reported as signal to cutoff ratios	At 2 weeks to 2 months following the second dose Overall: 100% positive Pregnant: 27.03 (±10.72) Non-pregnant: 34.35 (±10.25)	Not shown	Not shown	Anti-RBD IgG responses did not differ according to trimester of vaccination	Access SARS-CoV-2 IgG assay, Beckman Coulter	[31]
USA December 2020–March 2021	Two doses BNT162b2: 37% mRNA-1273: 63%	30		Vaccinated: 16 lactating women; 57 non-pregnant nonlactating women Previously infected: 6 non-pregnant women and 22 pregnant women	Anti-RBD IgG Neutralization responses Functional antibody responses T cell responses	Binding, neutralizing, and functional non-neutralizing antibody responses, and CD4 and CD8 T cell responses were present in pregnant, lactating, and non-pregnant women following vaccination	Binding and neutralizing antibodies were detected in cord blood	Vaccinated group: anti-RBD IgG cord blood 19 873 vs. mother 14 953 Neutralizing antibody in cord blood 324 vs. mother 1016 Infected group: anti-RBD IgG cord blood 635 vs. mother 1342 Neutralizing antibody in cord blood 164 vs. mother 151	Descriptive statistics only	In-house enzyme-linked immunosorbent assay	[32]
USA December 2020–March 2021	At least one dose BNT162b2: 49% mRNA-1273: 51%	84 Tested at baseline (v0), at the second dose (v1), at 2–6 weeks after the second dose (v2), and at delivery (v3)	First dose: 23.2 (16.3–32.1) weeks GA; 13% during the first trimester, 46% during the second trimester, 40% during the third trimester From second dose to delivery 14 (IQR: 11–16) days	Vaccinated: 31 lactating women 16 non-pregnant women 37 Women who had COVID-19 during pregnancy at 4–12 weeks before delivery	Anti-S IgM, IgG, and IgA Anti-RBD IgM, IgG, and IgA Neutralization responses at v3 Reported as mean fluorescence intensity	Antibody responses were similar in pregnant/lactating women and nonpregnant women Increase for all isotypes across all antigens from v0 to v1, further increase in IgG responses from v1 to v2 Spike responses increased quicker than RBD at v1 and v2 IgM and IgA responses were induced after first dose but not after second dose Neutralizing antibody: 104.7 (IQR: 61.2–188.2)	100% positive anti-S and anti-RBD IgG Neutralizing antibody: 52.3 (IQR: 11.7–69.6)	Not shown	Placental transfer ratio of anti-S IgG (but not anti-RBD) positively correlated with time from second dose to delivery No association between maternal responses and time of vaccination during pregnancy Higher responses is vaccinated women compared to pregnant women with natural infection	Multiplexed Luminex assay, ThermoFisher	[36]
Israel February–March 2021	Two doses BNT162b2	29	Third trimester	29 Women who had COVID-19 during pregnancy 21 Pregnant women not infected, not vaccinated	Anti-RBD IgG Reported as U/ml	Not shown	Vaccinated group: 100% positive; 224.7 U/ml (±64.3) Infected group: 100% positive; 83.7 U/ml (±91.6)	Not shown	Association between maternal and cord blood responses	Elecsys Anti-SARS-CoV-2 S immunoassay, Roche Diagnostics	[38]
Israel May–July 2021	Two doses, ≥7 days before delivery BNT162b2	129	Second trimester First dose: 21.9 (±3.3) weeks GA; second dose: 24.9 (±3.3) weeks GA From second dose to delivery 14.4 (±3.0) weeks	None	Anti-RBD IgG Reported as AU/ml	Overall: 100% positive 1185.2 AU/ml (range: 146.6–32415.1)	Overall: 100% positive; 3315.7 AU/ml (range: 350.1–17 643.5)	Approximately 2.6	Association between maternal and cord blood responses Maternal and cord blood responses correlated positively with GA at second dose Maternal and cord blood responses correlated inversely with the time from second dose to delivery and with maternal age	SARS-CoV-2 IgG II Quant, Abbott	[40]
USA January–March 2021	At least one dose BNT162b2: 64% mRNA-1273: 18% Unknown vaccine: 14% Two doses: 74%	27	Third trimester First dose: 33 (±2) weeks GA	None	Anti-RBD IgG and IgM Reported as AU/ml	96% positive anti-RBD IgG 56% positive anti-RBD IgM	89% positive anti-RBD IgG (negative cord bloods from two women who received their first dose <3 weeks before delivery); 0 positive anti-RBD IgM.	1.0 ± 0.6	Cord blood and placental transfer ratio of IgG associated positively with time from vaccination Cord blood IgG response associated positively with having received second dose.	DXI Platform, Beckman Coulter	[42]
Israel February–March 2021	Two doses, ≥14 days before delivery BNT162b2	64	Third trimesterS econd dose 33.5 (±3.2) weeks GA From second dose to delivery 21.7 (±11.0) days	11 Women who had COVID-19 during pregnancy at 92.5 (±75.8) days before delivery	Anti-RBD IgG Reported as signal to cutoff ratio	Vaccinated group: 100% positive; 26.1 (IQR: 22.0–39.7) Infected group: 2.6 (IQR: 0.9–3.5).	Vaccinated group: 98.3% positive; 20.2 (IQR: 12.7–29.0) Infected group cord blood: 3.3 (IQR: 0.5–4.6)	0.77	Association between maternal and cord blood responses Maternal responses associated negatively with time from second dose to delivery (but no correlation with cord blood IgG levels)	Access SARS-CoV-2 IgG assay, Beckman Coulter	[43]
USA January–March 2021	At least one dose BNT162b2: 70% mRNA-1273: 30% Two doses: 55%	122	Not shown	None	Anti-RBD IgG and IgM	Overall: 71% IgG-positive, 16% IgG- plus IgM-positive, 13% no detectable response (all women delivered within 4 weeks of first dose) By 4 weeks after first dose: 100% IgG-positive	Women who received 1 dose: 44% IgG-positive Women who received 2 doses: 99% IgG-positive	Not shown	Association between maternal and cord blood IgG responses Placental transfer ratio correlated positively with the number of weeks from second dose to delivery Maternal IgG responses increased week on week, from 2 weeks after first dose	Pylon 3D platform, ET HealthCare	[44]
Israel February 2021	Two doses BNT162b2	20	Third trimester From first dose to delivery 33 (IQR: 30–37) days From second dose to delivery 11 (IQR: 9–15) days	None	Anti-RBD IgG and IgM, and anti-S IgG Reported as AU/ml	100% positive anti-S and anti-RBD IgG; 30% positive anti-RBD IgM Anti-S IgG: 319 AU/ml (IQR: 211–1033) Anti-RBD IgG 11 150 (IQR: 6154–17 575)	100% positive anti-S and anti-RBD IgG 0% positive anti-RBD IgM Anti-S IgG: 193 AU/ml (IQR: 111–260) Anti-RBD IgG 3494 (IQR: 1817–6163)	Anti-S IgG: 0.44 (IQR: 0.25–0.61) Anti-RBD IgG: 0.34 (IQR: 0.27–0.56)	Association between maternal and cord blood anti-S and anti-RBD IgG responses Cord blood anti-S and anti-RBD IgG were associated positively with time from first dose to delivery	Anti-spike IgG and anti-RBD IgM: Liaison, DiaSorin, Saluggia, Italy Anti-RBD IgG: SARSCoV-2 IgG II Quant, Abbott	[46]
Israel February–April 2021	Two doses BNT162b2	171	Third trimester Early third trimester (27–31 weeks GA): 49% From first dose to delivery 71 (IQR: 63–79) days Late third trimester (32–36 weeks GA) From first dose to delivery 41 (IQR 34–50) days	None	Anti-RBD IgG and IgM Anti-S IgG Neutralization responses reported as AU/ml	Overall: 100% positive anti-S and anti-RBD IgG Early third trimester – anti-S IgG: 200 AU/ml (IQR: 143–296), anti-RBD IgG: 3980 AU/ml (IQR: 2414–7022), anti-RBD IgM: 0% Late third trimester – anti-S IgG: 292 AU/ml (IQR: 209–963), anti-RBD IgG: 8506 AU/ml (IQR: 4601–15 094), anti-RBD IgM: 18%	Overall: 100% positive anti-S and anti-RBD IgG 0% positive anti-RBD IgM Early third trimester: anti-RBD IgG: 9620 AU/ml (IQR: 5131–15 332) Late third trimester: anti-RBD IgG: 6697 AU/ml (IQR: 3157–14 731)	Early third trimester – anti-S IgG: 1.3 (IQR: 1.1–1.6), anti-RBD IgG: 2.3 (IQR: 1.7–3.0), neutralization: 1.9 (IQR: 1.7–2.5) Late third trimester – anti-S IgG: 0.9 (IQR: 0.6–1.1), anti-RBD IgG: 0.7 (IQR: 0.5–1.2), neutralization: 0.8 (IQR: 0.5–1.1)	Association between maternal and cord blood anti-S, anti-RBD IgG responses and neutralizing activity Maternal anti-S and anti-RBD IgG responses associated negatively with time from first dose to delivery Cord blood anti-RBD IgG and placental transfer ratio of anti-S, anti-RBD IgG and neutralizing activity higher after early vs. late third trimester vaccination, and were associated positively with time from first dose to delivery	Anti-spike IgG and anti-RBD IgM: Liaison, DiaSorin, Saluggia, Italy Anti-RBD IgG: SARSCoV-2 IgG II Quant, Abbott	[45]
USA July–October 2021	BNT162b2: 68% mRNA-1273: 32%	77	First dose: 20–32 weeks GA From first dose to delivery 85 (±46) days	12 Women who had COVID-19 during pregnancy at 20–32 weeks GA	Anti-S IgG Reported as optical density	Vaccinated group: 2.03 (±0.47) Infected group: 0.65 (±0.76)	Vaccinated group: cord blood 2.17 (±0.50); at 2 months of age 1.29 (±0.53), 98% positive; at 6 months of age 0.33 (±0.46), 57% positive Infected group: cord blood 1.00 (±0.83); at 6 months of age 0 (±0.01), 8% positive	Not shown	Responses at 2 months of age correlated positively with maternal and cord blood responses	In-house enzyme-linked immunosorbent assay	[49]
Israel May–July 2021	Two doses, ≥1 week before delivery BNT162b2	28	Second trimester Second dose: 26 (IQR: 14–34) weeks GA From second dose to delivery 11.1 (IQR: 9.3–15) weeks	12 Women who had COVID-19 during pregnancy at 20.6 (IQR: 17.6–36.9) weeks before delivery	Anti-S IgG Reported as AU/ml	Vaccinated group: 145 AU/ml (IQR: 113–202) Infected group: 41 AU/ml (IQR: 19–95)	Vaccinated group: 216 AU/ml (IQR: 155–316) Infected group: 64 AU/ml (IQR: 23–219)	Vaccinated group: 1.48 (IQR: 1.18–1.82) Infected group: 1.35 (IQR: 1.19–1.84)	Association between maternal and cord blood responses No association between maternal responses and placental transfer ratio No association between maternal responses and interval from vaccination to delivery Placental transfer ratio correlated positively with birthweight	Anti-spike IgG, Liaison, DiaSorin, Saluggia, Italy	[51]
Germany Start date not reported–June 2021	At least 1 dose BNT162b2: 72% mRNA-1273: 28% Two doses: 97%	36	First dose 6% during the first trimester, 83% during the second trimester, 11% during the third trimester From second dose to delivery 13 (range: 5.9–24.9) weeks	None	Anti-S IgG Reported as U/ml	100% positive	100% positive	Not shown		Elecsys anti-SARS-CoV-2 assay, Roche Diagnostics	[52]
USA March–October 2021	At least one dose BNT162b2: 75% mRNA-1273: 22% Ad26.COV2.S: 2% Two doses: 89% Booster dose: 1%	1359 12.8% had history of SARS-CoV-2 infection	First dose: 3% pre-pregnancy, 14% during the first trimester, 51% during the second trimester, 32% during the third trimester	None	Anti-S IgG Reported as relative index value	Anti-S IgG levels in fully vaccinated women by trimester of vaccination: 4.1 (pre-pregnancy), 4.2 (first trimester), 4.9 (second trimester), 6.2 (third trimester)	Anti-S IgG levels in cord blood from fully vaccinated women by trimester of vaccination: 4.5 (pre-pregnancy); 4.7 (first trimester); 5.5 (second trimester); 6.3 (third trimester)	Not shown	Third trimester vaccination associated with highest responses in maternal and cord blood Ad26.COV2.S no difference in responses by trimester of vaccination and always lower than the mRNA vaccines In women with history of SARS-CoV-2 infection, maternal and cord blood responses after vaccination in early pregnancy were comparable to third trimester vaccination in pregnant women without history of infection	Pylon 3D platform, ET HealthCare	[55]
Poland Dates not reported	Two doses BNT162b2	16	First dose: 31.8 (±2.1) weeks GA Second dose 35.1 (±2.1) weeks GA From second dose to delivery 5.5 (±2.1) weeks	None	Anti-RBD IgG Reported as U/ml	100% positive 984.37 U/ml (±689.4)	100% positive 1026.51 U/ml (±769.25)	1.28 (±0.80)	Cord blood and placental transfer ratio associated positively with time from first dose and second dose to delivery	Elecsys Anti-SARS-CoV-2-S-RBD assay, Roche Diagnostics	[57]
Romania May–December 2021	BNT162b2 Ad26.CO	227	Third trimester	54 Pregnant women who had COVID-19 529 Non-pregnant vaccinated women, uninfected	Anti-RBD IgG Reported as U/ml	Vaccinated group not previously infected – before vaccination: 0.41 (0.31–0.45); 1 month post-fully vaccinated: 2433 (1752–3094); 2 months post-fully vaccinated: 1697 (1393–2115); 3 months post-fully vaccinated: 1314 (1095–1762); 4 months post-fully vaccinated: 1083 (896–1468) Vaccinated group previously infected – before vaccination: 145 (98.2–208.1); 1 month post-fully vaccinated: 15 360 (13 551–16 318); 2 months post-fully vaccinated: 14 571 (12 628–15 337); 3 months post-fully vaccinated: 12 870 (10 644–14 349); 4 months post-fully vaccinated: 10 759 (9043–12 571) Non-pregnant group – before vaccination: 0.40 (0.32–0.47); 1 month post-fully vaccinated: 2461 (1719–3176); 2 months post-fully vaccinated: 1705 (1452–2179); 3 months post-fully vaccinated: 1377 (1147–1822); 4 months post-fully vaccinated: 1114 (909–1483)	Not shown	Not shown		Elecsys Anti-SARS-CoV-2-S-RBD assay, Roche Diagnostics	[59]

^aAbbreviations: AU/ml, arbitrary units per milliliter; GA, gestational age; IQR, interquartile range; RBD, receptor-binding domain; S, spike protein; U/ml, units per milliliter.

^bBlood samples collected at delivery if not stated otherwise.