Human Papillomavirus (HPV) Vaccine Update

Cheryl Lau, PharmD Candidate Class of 2021; Hayden Carrion, PharmD Candidate Class of 2021; Michele Pisano, PharmD, BCGP, CDE; Carmela Avena-Woods, BS Pharm, PharmD, BCGP


US Pharmacist. 2020;45(9):17-20. 

In This Article


Each HPV vaccine underwent extensive safety testing before being FDA approved. Data collected from the Vaccine Adverse Event Reporting System (VAERS) from June 2006 to June 2017 showed that of more than 80 million doses of Gardasil administered, there were 36,142 reports of adverse events, with 96% of the adverse events being classified as nonserious. The most common adverse effects included dizziness, fatigue, injection-site reactions, and headache. Safety studies of Gardasil provided safety data that was relevant for Gardasil9.[17] From December 2014 to December 2017, 28 million doses of Gardasil9 were distributed throughout the U.S. Postlicensure surveillance reports to VAERS showed that of 7,244 reports received after administration of Gardasil9, 97.4% were nonserious.[18] Similar to its predecessor, the most common reported adverse events were dizziness, syncope, headache, and injection-site reactions (Table 2). Rare but severe adverse events of Gardasil9 included anaphylaxis, allergic reaction, appendicitis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, injection-site reaction, pancreatitis, stroke, seizure, and venous thromboembolism[17] (Table 3).

Additional data from Vaccine Safety Datalink (VSD) showed that of 838,991 doses administered from October 2015 to October 2017, there were eight cases of pancreatitis in men ages 18 to 26 who were exposed to the vaccine. A medical record review determined that seven of eight cases were either not incident or attributable to causes other than vaccination; thus, the relative risk (RR), although slightly elevated, was not statistically significant (RR = 4.7, P = 0.47).[19] Thirty cases of acute appendicitis, the most frequent serious adverse event, were reported within 42 days of vaccination. However, further analysis failed to confirm causal association. VSD also found a postvaccination-related allergic reaction to be consistent with prelicensure clinical trials, in which serious allergic reactions were rare.[19] After 2 years of weekly surveillance of the 9-valent HPV vaccine, no new safety concerns were identified. Meta-analysis of prospective controlled studies also found most adverse reactions to be transient.[20]

Parents may be hesitant to immunize their child based on the notion that vaccines pose a risk of infecting their child with the disease it is meant to prevent. Some may also believe that natural immunity is better than vaccine-acquired immunity. Not only have vaccines been extensively studied and proven safe but they are also continuously monitored for safety as long as they are being used. Vaccines are capable of causing adverse effects that may be confused with the disease itself. However, these adverse effects tend to be minor and can be treated with supportive care. Furthermore, the benefits of HPV vaccine far outweigh any potential risk of side effects. Within 10 years of Gardasil's release, the CDC analyzed data reported by HPV-IMPACT and determined there had been an 86% decrease in HPV infections among those aged 14 to 19 years and a 71% decrease among those aged 20 to 24 years in the U.S.[17] From 2008 to 2012, prevalence of HPV 16/18 in cervical intraepithelial neoplastic (CIN2+) lesions showed a statistically significant decrease from 53.6% to 28.4% among women who received at least one vaccine dose.[21]