What is Imvanex and smallpox vaccine used for?
Imvanex is a vaccine used for immunization against smallpox in adults. Contains a live modified form of the Vaccinia virus called "Vaccinia Ankara". This virus is related to the smallpox virus, but does not cause the disease in humans and has been modified so that it cannot replicate (or reproduce) in human cells. The vaccine was officially declared eradicated in 1980; the last known case of the disease was recorded in 1977. This vaccine will be used in situations where it is considered necessary to ensure protection against smallpox, in accordance with official recommendations.
How is Imvanex - Smallpox vaccine used?
Imvanex is available as a suspension for subcutaneous injection, preferably in the shoulder. In people who have not been previously vaccinated against smallpox two doses of 0.5 ml should be used; the second dose should be administered at least 28 days after the first one. If it is considered necessary to administer a booster dose in subjects who have been vaccinated against smallpox in the past, a single dose of 0.5 ml should be administered, with the exception of patients with an immune system (the body's natural defenses) weakened, which must receive two booster doses, of which the second at least 28 days after the first one. The vaccine can only be obtained with a prescription.
How does Imvanex - smallpox vaccine work?
Vaccines act by "teaching" the immune system to defend itself against a disease. When a person is vaccinated, the immune system recognizes the viruses in the vaccine as "foreign" and produces antibodies against those viruses. When this person is again exposed to these viruses or similar viruses, the antibodies, along with other components of the immune system, will be able to kill viruses and protect the body from disease. Imvanex contains a modified form of the Vaccinia virus, which does not cause disease in humans and cannot replicate in human cells. The antibodies produced against this virus are expected to provide protection against smallpox due to its similarities to the smallpox virus. Vaccinia virus vaccines have been used effectively in the campaign to eradicate smallpox.
What benefit has Imvanex - smallpox vaccine shown during the studies?
During the studies Imvanex has been shown to be effective in stimulating the production of antibodies at a level that is expected to guarantee immunization against smallpox. Five important studies were conducted, involving more than 2, 000 adults, including patients with HIV and atopic dermatitis (an itchy skin manifestation caused by an overactive immune system) and people who had previously been vaccinated against smallpox. Two of the studies looked in particular at the effectiveness of Imvanex as a booster vaccination. Although studies have shown that Imvanex should ensure immunization against smallpox, the exact level of protection and its duration cannot be determined from the study results.
What is the risk associated with Imvanex - Smallpox vaccine?
The most common side effects with Imvanex (seen in more than 1 in 10 people) are headache, nausea, myalgia (muscle pain), fatigue and reactions at the injection site (pain, redness, swelling, hardening and itching). For the full list of all side effects reported with Imvanex, see the package leaflet. Imvanex must not be used in patients who are hypersensitive (allergic) to the active substance or to any of the other trace ingredients, such as chicken proteins, benzonase and gentamicin.
Why has Imvanex - smallpox vaccine been approved?
The Committee for Medicinal Products for Human Use (CHMP) noted that Imvanex is effective in stimulating the production of antibodies at a level that is expected to ensure immunization against smallpox, although the exact level and duration of protection that would be guaranteed in the during an epidemic are not known. As for safety, the Vaccinia virus present in Imvanex cannot replicate in human cells and, therefore, is less likely to cause side effects than previous smallpox vaccines. Imvanex would therefore offer benefits to people who cannot be immunized with vaccines containing replicating viruses, such as those with a weakened immune system. Taking into account all the data, the CHMP decided that Imvanex's benefits are greater than its risks and recommended that it be approved for use in the EU. Imvanex was authorized in "exceptional circumstances" because complete information on Imvanex could not be obtained due to the non-existence of the disease. Every year the European Medicines Agency will review the new information available and this summary will be updated accordingly.
What information is still awaited for Imvanex - Smallpox vaccine?
As Imvanex has been authorized in exceptional circumstances, the company that markets Imvanex will provide additional data from studies on changes in the levels of antibodies observed in vaccinated persons. Additional data on the benefits and risks of the vaccine will be collected in observational studies in vaccinated patients as well as in the event that a smallpox epidemic should emerge in the future.
What measures are being taken to ensure the safe and effective use of Imvanex - Smallpox vaccine?
A risk management plan has been developed to ensure that Imvanex is used as safely as possible. Based on this plan, safety information has been included in the summary of product characteristics and the information sheet for Imvanex, including the appropriate precautions to be followed by healthcare professionals and patients.
Other information about Imvanex - Smallpox vaccine
On 31 July 2013, the European Commission issued a marketing authorization for Imvanex, valid throughout the European Union. For the full EPAR for Imvanex consult the website of the Agency: ema.Europa.eu/Find medicine / Human medicines / European public assessment reports. Last update of this summary: 07-2013.
