The European Medicines Agency announced Monday that it has launched a safety review of the three vaccines for human papillomavirus (HPV) after receiving reports of serious adverse reactions in some young women.

EMA officials said the incidents were rare, but that they were "concerned" by the severity of two types of conditions that had come to their attention. The first is known as complex regional pain syndrome or CRPS and is a chronic pain condition affecting the limbs. The second one, postural orthostatic tachycardia syndrome or POTS, occurs when the heart rate jumps abnormally when sitting or standing. That can lead to dizziness, fainting, headache, chest pain and weakness.

The HPV vaccine, which involves three shots over six months, is one of the most widely used new vaccines. About 72 million people worldwide have received the course which protects against several strains of HPV that are linked to cervical cancer, genital warts and other cancers. In the United States, public health officials have campaigned aggressively over the past few years using everything from birthday card direct mailings to social media campaigns to get children -- both boys and girls -- to get the vaccine.

The Centers for Disease Control and Prevention recommends that all children who are 11 or 12 should get the vaccine. Virginia and the District of Columbia require the vaccine for girls entering sixth grade. Rhode Island passed similar legislation that will take effect this fall, and many other states provide funding for the vaccine or public education to encourage parents and children to get it. Despite these efforts, rates of vaccination -- about a third of teenagers -- have fallen short of government goals and lag behind other countries, such as Australia. A study published in the journal Pediatrics on the subject found that many parents in the United States felt the vaccine was "not needed or necessary" and a number of parents -- 16.4 percent in 2010 -- had safety concerns.

The EMA, which is similar to the U.S. Food and Drug Administration but is not a regulatory agency but one focused on science and that makes recommendations to the European Commission, said that the review would involve Gardasil/Silgard, Gardasil 9, and Cervarix.

Launched at the request of officials in Denmark, the investigation will attempt to determine the frequency of such events and to determine whether there is any causal link. The EMA cautioned in a statement that these types of symptoms "can occur in non-vaccinated individuals."

The European agency said it is not recommending any changes in the use of the vaccine while the review is being conducted and that the review "does not question that the benefits of HPV vaccines outweigh their risks."

The CDC considers HPV vaccines "very safe" overall and in 2014 published a report analyzing events related to Gardasil 9 (the newest of those in use) to a national vaccine adverse event system and found that 92 percent were non-serious and involved fainting, dizziness, nausea, headache, fever and injection site pain. According to consumer guidance provided by the CDC, "brief fainting spells and related symptoms (such as jerking movements) can happen after any medical procedure, including vaccination."

Concerns in Denmark were prompted by a documentary aired by publicly owned TV2 entitled "The Vaccinated Girls – Sick and Betrayed."

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