HPV Vaccine Safety and Effectiveness Data

More than 15 years of monitoring and research have accumulated reassuring evidence that human papillomavirus (HPV) vaccination provides safe, effective, and long-lasting protection against cancers caused by HPV infections.

Data from Clinical Trials

Each HPV vaccine—9-valent HPV vaccine (Gardasil® 9), quadrivalent HPV vaccine (Gardasil®), and bivalent HPV vaccine (Cervarix®)—went through years of strict safety testing before the U.S. Food and Drug Administration (FDA) licensed it. Each vaccine was found to be safe and effective in clinical trials.


Gardasil 9 was studied in clinical trials with more than 15,000 females and males.


Gardasil was studied in clinical trials with more than 29,000 females and males.


Cervarix was studied in clinical trials with more than 30,000 females.

Since late 2016, Gardasil 9 has been the only HPV vaccine available for use in the United States.

Vaccine Safety Monitoring Data

With more than 135 million doses of HPV vaccines distributed in the United States, there are robust data showing that HPV vaccines are safe.

  • Like any vaccine or medicine, HPV vaccines can cause side effects. The most common side effects reported through CDC’s Vaccine Adverse Event Reporting System (VAERS) are pain, redness, or swelling in the arm where the vaccine was given, dizziness, syncope (fainting), nausea, and headache.
  • With the exception of syncope, which is more common among adolescents after receiving any vaccine, there have been no confirmed adverse events occurring at higher than expected rates following HPV vaccination.
  • On very rare occasions, a person may have a serious allergic reaction (anaphylaxis) to any vaccine, including HPV vaccines. In the United States, anaphylaxis following vaccination has a reported rate of 3 cases per 1 million doses administered. People with severe allergies to any component of a vaccine should not receive that vaccine.
Vaccine Safety Monitoring in the United States

The United States monitors safety of all vaccines through several systems:

  • Vaccine Adverse Events Reporting System (VAERS) is a spontaneous reporting system that serves as an early warning system to detect possible safety problems that may be related to vaccination. Anyone can submit a report to VAERS. However, it is generally not possible to find out from VAERS data if a vaccine caused the adverse event, and the reports often lack details and sometimes contain errors.
  • Vaccine Safety Datalink (VSD) is a collaborative project between CDC and eight healthcare organizations that monitors the safety of vaccines and conducts rigorous vaccine safety assessments.
  • Clinical Immunization Safety Assessment Project (CISA) conducts vaccine safety clinical research and assesses complex clinical adverse events following vaccination.

While only Gardasil 9 has been available for use in the United States since late 2016, safety studies of Gardasil have provided important safety information relevant for Gardasil 9 (Gardasil and Gardasil 9 are similar types of vaccines and are produced by the same manufacturer). Studies of Cervarix have also shown a favorable safety profile. While the vaccines prevent infections with some different HPV types, all three HPV vaccines are similar, and based on a single protein of the human papillomavirus.

What is an adverse event?

  • An “adverse event” is any health problem that happens after a shot or other vaccine. An adverse event might be truly caused by a vaccine, or it might be pure coincidence.
  • An adverse event is defined by law as “serious” if it is life-threatening or results in death, a persistent or significant disability or incapacity, congenital anomaly or birth defect, hospitalization, or prolongation of existing hospitalization.
  • VAERS data alone usually cannot be used to answer the question, “Does a certain vaccine cause a certain adverse event?” This is mainly because adverse events reported to VAERS may or may not be caused by vaccines.
  • VAERS reports help provide medical professionals at CDC and FDA with a signal of a potential adverse event that needs to be studied further.

Data on Gardasil 9 (9vHPV)

Data on Gardasil (4vHPV)

Gardasil is no longer available in the United States.

Data on Cervarix (2vHPV)

Cervarix is no longer available in the United States and was not administered at any of the VSD sites; therefore, no safety monitoring was conducted through the VSD network.

Vaccine Safety Studies of Specific Conditions

Complex Regional Pain Syndrome (CRPS)

Postural Orthostatic Tachycardia Syndrome (POTS)

Primary Ovarian Insufficiency (POI)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Autoimmune Conditions

Several large studies have looked at whether HPV vaccines cause autoimmune disease. Many different autoimmune diseases have been studied, including Guillain–Barré syndrome, multiple sclerosis, and diabetes. To date, these studies have not found any association between HPV vaccination and autoimmune conditions.(6-9, 12-18, 20, 28)


Vaccine Effectiveness Studies

Studies in the United States and other countries have shown that HPV vaccination is already preventing cancer-causing infections, anogenital warts, and cervical precancers. Some data from other countries have found early evidence of a vaccine effectiveness against cervical cancer.

Duration of Protection Studies

Data from clinical trials and ongoing research show that HPV vaccination provides long-lasting protection.

  • Protection by HPV vaccination lasts for more than 10 years without becoming less effective.(38, 39, 40, 41)
  • Studies are ongoing to further evaluate the duration of protection.
  • No data indicate that the protection from HPV vaccination lessens over time.