Table 4.
Summary of Adverse Events.*
| Adverse Event | Quadrivalent HPV Vaccine | Placebo | Difference in Risk (95% CI) percentage points |
P Value† |
|---|---|---|---|---|
| no. (%) | ||||
| No. of subjects | 2020 | 2029 | ||
| No. of subjects with follow-up data | 1945 | 1950 | ||
| Subjects with events during entire study period | ||||
| No event | 599 (30.8) | 698 (35.8) | ||
| One or more events | 1346 (69.2) | 1252 (64.2) | 5.0 (2.0 to 8.0) | <0.001 |
| Injection site | 1169 (60.1) | 1047 (53.7) | 6.4 (3.3 to 9.5) | <0.001 |
| Systemic | 616 (31.7) | 622 (31.9) | −0.2 (−3.2 to 2.7) | 0.88 |
| Vaccine-related events‡ | 1242 (63.9) | 1134 (58.2) | 5.7 (2.6 to 8.8) | <0.001 |
| Injection site | 1169 (60.1) | 1046 (53.6) | 6.5 (3.3 to 9.6) | <0.001 |
| Systemic | 274 (14.1) | 284 (14.6) | −0.5 (−2.7 to 1.7) | 0.67 |
| Serious events§ | 8 (0.4) | 11 (0.6) | −0.2 (−0.7 to 0.3) | 0.49 |
| Serious vaccine-related events‡§ | 0 | 0 | 0.0 (−0.2 to 0.2) | 1.00 |
| Death | 3 (0.2) | 10 (0.5) | −0.4 (−0.8 to 0.01) | 0.052 |
| Subjects with adverse events in first 15 days after injection | ||||
| No event | 600 (30.8) | 706 (36.2) | ||
| One or more events | 1345 (69.2) | 1244 (63.8) | 5.4 (2.4 to 8.3) | <0.001 |
| Injection site | 1169 (60.1) | 1047 (53.7) | 6.4 (3.3 to 9.5) | <0.001 |
| Systemic | 615 (31.6) | 613 (31.4) | 0.2 (−2.7 to 3.1) | 0.90 |
| Vaccine-related events‡ | 1242 (63.9) | 1134 (58.2) | 5.7 (2.6 to 8.8) | <0.001 |
| Injection site | 1169 (60.1) | 1046 (53.6) | 6.5 (3.3 to 9.6) | <0.001 |
| Systemic | 274 (14.1) | 284 (14.6) | −0.5 (−2.7 to 1.7) | 0.67 |
| Serious events§ | 5 (0.3) | 1 (0.1) | 0.2 (−0.1 to 0.6) | 0.10 |
| Serious vaccine-related events‡§ | 0 | 0 | 0 (−0.2 to 0.2) | 1.00 |
| Death | 0 | 0 | 0 (−0.2 to 0.2) | 1.00 |
Percentages were calculated on the basis of the number of subjects with follow-up data. HPV denotes human papillomavirus.
P values have not been adjusted for multiple comparisons.
Vaccine-related events were those determined by the investigator to be possibly, probably, or definitely related to the vaccine.
Serious adverse events in the vaccine group included appendicitis, cellulitis, noncardiac chest pain, hypersensitivity (peanut allergy), chickenpox-related seizure, traffic accident (there were two such accidents, both resulting in death), and gunshot wound (resulting in death). Serious adverse events in the placebo group included contusion related to traffic accident and the following fatal events: gunshot wound (in 3 subjects), drug overdose (2), suicide (2), traffic accident (1), chemical poisoning (1), and myocardial ischemia (1). Three additional subjects were considered to have serious adverse events because they received more than 3 doses of vaccine or placebo; none of these subjects had adverse events after any of the injections they received.