Immunogenicity and reactogenicity of heterologous COVID-19 vaccination in pregnant women

Figures & data

Figure 1. Consort flow diagram. One hundred and sixty-five participants were screened and 150 determined eligible to participate in the study. Participants were randomized 1:1:1 into three study arms (50 each) and assessed pre-vaccination (baseline), four weeks after the first vaccination, two weeks after the second vaccination, and upon delivery (after excluding baseline seropositive patients).

Table 1. Participant characteristics by COVID-19 vaccine regimen.

		Vaccination type
First vaccination — Second vaccination	Total	BNT162b2 — BNT162b2	ChAdOx1 — BNT162b2	CoronaVac — BNT162b2	P-value^a
Numbers of included participants	n = 124	n = 44	n = 37	n = 43
Age [median (IQR)], years	31.00 (26.00, 35.50)	31.00 (28.00, 36.00)	33.00 (26.00, 35.00)	29.00 (25.00, 34.00)	.2431
Gestational age [median (IQR)], weeks	23.50 (18.00, 30.00)	25.00 (20.50, 31.50)	24.00 (18.00, 30.00)	20.00 (16.00, 29.00)	.7315
BMI [median (IQR)], kg/m^Citation2	23.90 (21.15, 27.55)	25.95 (22.15, 28.10)	23.60 (22.00, 27.80)	23.60 (20.90, 26.70)	.2893
Underlying disease, n (%)
Hepatitis B inactive carriers	2 (1.61)	0	2 (5.41)	0	0
Thalassemia trait	25 (20.16)	11 (25.00)	7 (18.92)	7 (16.28)	.5154
Gestational diabetes	5 (4.03)	2 (4.55)	1 (2.70)	3 (6.98)	.3012
Number of participants at delivery	n = 89	n = 36	n = 26	n = 27	…
Gestational age at delivery [median (IQR)], week	38.00 (37.00, 39.00)	38.00 (37.00, 39.00)	38.00 (37.00, 39.00)	38.00 (38.00, 39.00)	.8890
Preterm delivery (<37^b weeks of gestation), n (%)	10 (11.24)	4 (11.11)	5 (19.23)	1 (3.70)	.2016
Abortion or miscarriage, n (%)	0	0	0	0	0
Low birth weight (<2,500 g), n (%)	6 (6.74)	3 (8.33)	2 (7.69)	1 (3.70)	.7487

^aChi-squared test and Kruskal-Wallis tests were used to determine p-values. ^bAll had a gestational age between 35–36 weeks. Abbreviations: IQR, Interquartile Range; BMI, Body Mass Index.

Figure 2. Maternal humoral immune responses four weeks after the first dose and two weeks after the second dose. (a) Illustrates anti-SARS-CoV-2 receptor binding domain (RBD) IgG geometric mean concentrations (GMCs), with references of the same vaccine regimens in healthy, non-pregnant adults for comparison.²² (b) Illustrates geometric mean titers (GMTs) of neutralizing antibodies (NAbs) from 50% inhibitory dilution (ID₅₀) by microneutralization assays against the ancestral Wuhan strain and Omicron BA.1, BA.2, and BA.5 subvariants. Titers below the lower limit of detection (LLOD of 1:10) were replaced with a value of 10. Error bars represent geometric means with 95% confidence intervals (CIs). Abbreviations: BAU, Binding Antibody Units; ID₅₀, 50% Inhibitory Dilution.

Figure 3. (a) Comparative geometric mean concentrations (GMCs) of maternal and cord blood anti-SARS-CoV-2 RBD IgG at delivery by vaccine regimen. (b) Pearson’s correlation coefficient (PCC) of umbilical cord anti-RBD IgG level against maternal anti-RBD IgG at delivery. (c) PCC of maternal anti-RBD IgG at time of delivery against time since the second vaccination. (d) PCC of umbilical cord blood anti-RBD IgG at the time of delivery against time since the second vaccination. (r) represents PCC.

Figure 4. Self-reported local (a) and systemic (b) adverse events (AEs) within the first seven days after each vaccination by vaccine regimen.

Phoswa WN, Khaliq OP. Is pregnancy a risk factor of COVID-19? Eur J Obstet Gynecol Reprod Biol. 2020;252:605–9. doi:10.1016/j.ejogrb.2020.06.058.

 PubMed Web of Science ®Google Scholar

Niyomnaitham S, Quan Toh Z, Wongprompitak P, Jansarikit L, Srisutthisamphan K, Sapsutthipas S, Jantraphakorn Y, Mingngamsup N, Licciardi PV, Chokephaibulkit K, et al. Immunogenicity and reactogenicity against the SARS-CoV-2 variants following heterologous primary series involving CoronaVac, ChAdox1 nCov-19 and BNT162b2 plus BNT162b2 booster vaccination: an open-label randomized study in healthy Thai adults. Hum Vaccin Immunother. 2022;18(6):2091865. doi:10.1080/21645515.2022.2091865.

 PubMed Web of Science ®Google Scholar

Data availability statement

Deidentified individual patient information and other datasets, study protocols, and documents generated and/or analyzed during this study will be made available after publication and shared to researchers with a methodologically sound proposal to achieve their aims upon request, by e-mail, to the corresponding author.