Table II.
Effectiveness∗ of maternal BNT162b2 SARS-CoV-2 vaccination against SARS-CoV2-associated hospitalization in infants <6 months, for fully and partially vaccinated mothers by infant age at admission
| SARS-COV-2 PCR negative infants (n = 348) | SARS-COV-2 PCR positive infants (n = 116) | Vaccine effectiveness∗ (CI) | P value | |
|---|---|---|---|---|
| All infants unadjusted | ||||
| Unvaccinated mothers | 181 (69.1%) | 81 (30.9%) | ||
| Partially vaccinated mothers | 62 (79.5%) | 16 (20.5%) | 42.3% (0.0-68.6) | 0.045 |
| Fully vaccinated mothers | 105 (84.7%) | 19 (15.3%) | 59.6% (29.6-76.8) | 0.001 |
| All infants adjusted | ||||
| Unvaccinated mothers | 181 (69.1%) | 81 (30.9%) | ||
| Partially vaccinated mothers† | 62 (79.5%) | 16 (20.5%) | 41.7% (0.0-68.6) | .087 |
| Fully vaccinated mothers‡ | 105 (84.7%) | 19 (15.3%) | 61.6% (31.9-78.4) | .001 |
| All infants excluding mothers who received a third dose of the vaccine | ||||
| Unvaccinated mothers | 181 (69.1%) | 81 (30.9%) | ||
| Partially vaccinated mothers | 62 (79.5%) | 16 (20.5%) | 42.3% (0.0-68.6) | .045 |
| Fully vaccinated mothers | 105 (84.7%) | 19 (15.3%) | 57.1% (22.8-76.4) | .004 |
| Infants <2 months | ||||
| Unvaccinated mothers | 119 (67.2%) | 58 (32.8%) | ||
| Partially vaccinated mothers | 43 (78.2%) | 12 (21.8%) | 42.7% (0.0-71.9) | .122 |
| Fully vaccinated mothers | 85 (85.0%) | 15 (15.0%) | 63.8% (31.9-80.8) | .001 |
| Infants 2-6 months of age | ||||
| Unvaccinated mothers | 62 (72.9%) | 23 (27.1%) | ||
| Partially vaccinated mothers | 19 (82.6%) | 4 (17.4%) | 43.3% (0.0-82.6) | .342 |
| Fully vaccinated mothers | 20 (83.3%) | 4 (16.7%) | 46.1% (0.0-83.4) | .298 |
| Infants with severe infection | ||||
| Unvaccinated mothers | 36 (73.4%) | 13 (26.6%) | ||
| Partially vaccinated mothers | 9 (75%) | 3 (25%) | 7.7 (0.0-78.0) | 1.0 |
| Fully vaccinated mothers | 16 (94.1%) | 1 (5.9%) | 82.7 (0.0-97.9) | .093 |
| All infants excluding infants of SARS-COV-2 infected mothers during pregnancy | ||||
| Unvaccinated mothers | 166 (67.5%) | 80 (32.5%) | ||
| Partially vaccinated mothers | 58 (80.6%) | 14 (19.4%) | 49.9% (4.9-73.6) | .032 |
| Fully vaccinated mothers | 102 (84.3%) | 19 (15.7%) | 61.4% (32.5-77.9) | <.001 |
∗
Vaccine effectiveness estimates were based on odds of antecedent maternal vaccination during pregnancy in case infants vs control-infants.
†
Adjusted for ethnicity and infant age.
‡
Adjusted for ethnicity and prematurity.