(HealthDay News) — The safety of the 9-valent human papillomavirus vaccine (9vHPV) has been confirmed, according to two studies published online Nov. 18 in Pediatrics.

Tom T. Shimabukuro, M.D., M.P.H., from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues searched the Vaccine Adverse Event Reporting System (VAERS) for reports of adverse events (AEs) after 9vHPV from December 2014 through December 2017. The researchers found that the VAERS received 7,244 reports after 9vHPV; 97.4 percent were nonserious. Two reports of death were verified after 9vHPV, but no evidence indicated a causal relationship with the vaccination. During the study period, crude AE reporting rates were 259 reports per million 9vHPV doses distributed for all reports and seven per million doses distributed for serious reports.

James G. Donahue, D.V.M., Ph.D., from the Marshfield Clinic Research Institute in Wisconsin, and colleagues extracted data on immunizations and AEs from October 2015 to October 2017 at six Vaccine Safety Datalink sites. A total of 838,991 doses of 9vHPV were administered during 105 weeks of surveillance. The researchers identified four AEs with unexpected statistical signals: appendicitis after dose 3 in boys aged 9 to 17 years; pancreatitis in men aged 18 to 26 years; and allergic reactions after dose 2 in girls aged 9 to 17 and women aged 18 to 26 years. Signals were not confirmed for any AEs on further evaluation, including medical record review, temporal scan analysis, and additional epidemiological analyses.

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“Deferral of HPV vaccination because of questions regarding safety can no longer be defended as a reasonable option,” write the authors of an accompanying editorial.

One author from the Shimabukuro study disclosed employment with Merck; his work on this study ceased before this employment. Two authors from the Donahue study disclosed financial ties to the pharmaceutical industry.

Abstract/Full Text – Shimabukuro (subscription or payment may be required)

Abstract/Full Text – Donahue (subscription or payment may be required)

Editorial (subscription or payment may be required)