Research by Australian scientists has found that adverse reactions to the HPV vaccine Gardasil are rare and most schoolgirls are able to tolerate subsequent doses.
The study led by Dr. Sharon Choo and colleagues from the Royal Children's Hospital in Melbourne involved 25 Australian girls with suspected hypersensitivity to the vaccine.
The vaccine was given to all Australian females aged 12 to 26 years as part of a national immunisation programme beginning in 2007.
Some components of the vaccine such as aluminium salts and yeast have previously been associated with hypersensitivity reactions and some reports of adverse events followed the school vaccination programme.
The study is the first evaluation of the quadrivalent HPV vaccine after more than 380,000 vaccine doses were given in schools in Victoria and South Australia.
Thirty five schoolgirls with suspected hypersensitivity reactions including urticaria (hives), generalised rash, angioedema (swelling of subcutaneous tissues) and anaphylaxis were reported to specialised immunisation services and 25 agreed to be referred to paediatric allergy centres for further evaluation.
The researchers kept a detailed account of the reactions which included previous doses of the vaccine, time and severity of reaction, and previous clinical history and skin prick tests of the HPV vaccines were carried out.
The girls were followed-up by telephone one week after the subsequent dose and any adverse events were recorded and the research team found that only one reported a negative reaction of hives which occurred four hours after the vaccine was given.
The researchers suggest that only three of the 25 evaluated schoolgirls possibly had hypersensitivity to the vaccine, and they say true hypersensitivity is uncommon.
They say that suspected hypersensitivity reactions such as hives are often "idiosyncratic" and do not increase the risk of adverse reactions in subsequent vaccinations.
The authors recommend that girls with suspected hypersensitivity to the quadrivalent vaccine should be evaluated before receiving more doses, and call for research into the mechanisms of hypersensitivity to the vaccine.
Gardasil and Cervarix are vaccines designed to be given to girls and young women to protect them against cancer-causing strains of the sexually transmitted human papillomavirus (HPV), which can cause cervical cancer.
Gardasil targets four strains of HPV -- two responsible for cervical cancer and two causing the less serious condition of genital warts while Cervarix targets the two cancer strains.
In October this year the U.S. Centres for Disease Control and Prevention (CDC) reported that girls and young women given Gardasil were no more likely than usual to faint, have an allergic reaction, blood clot or other adverse reaction.
The research is published in the British Medical Journal.