By: Dr. Maria Alice
Consultant in General and Family Medicine
Director – Luzdoc International Medical Service
IN THE US, the Food and Drug Administration (FDA) has approved the first Avian Influenza Virus (H5N1) vaccine and a British firm is developing a vaccine against high blood pressure.
Bird Flu vaccine for humans
On April 17, the FDA has approved an inactivated, monovalent Avian Influenza vaccine for the active immunisation against the H5N1 Influenza virus, commonly known as Avian Influenza or Bird Flu, for adults aged 18 to 64, who are at increased risk of exposure to the H5N1 viral subtype contained in the product. The immunisation regimen consists of two doses administered by intramuscular injection with an interval of 28 days.
The vaccine could be used if the current H5N1 avian virus were to mutate into a form that could spread easily from human to human, triggering a pandemic. An influenza pandemic is a worldwide outbreak of disease that occurs when a new strain of influenza virus circulates and causes serious illness in a large number of people.
Approval of the vaccine was based on clinical study data showing that the use of two recommended doses created an adequate immune response against the H5N1 virus in 45 per cent of subjects. In the remaining patients, the FDA also states that current scientific information suggests that disease severity and influenza-related hospitalisation and death may be reduced.
The vaccine was generally well tolerated, with the most commonly reported adverse events being injection-site pain, headache, general ill feeling and muscle pain.
The vaccine contains chicken and egg proteins, so caution is advised in patients with known hypersensitivity reactions to egg proteins.
The FDA notes that additional information regarding the safety of the vaccine in other age groups is currently being obtained. In addition, a next generation of influenza vaccines is being developed to boost immune response with lower doses.
Is influenza pandemic still a threat?
The threat of an influenza pandemic is, at present, one of the most significant public health issues our nation and world faces,” said Andrew C. von Eschenbach, MD, commissioner of food and drugs, in an FDA news release. “The approval of this vaccine is an important step forward in our protection against a pandemic.” Right now, there is no influenza pandemic, but each illness in humans gives the virus an opportunity to improve its ability to spread from human to human and develop into a pandemic strain.
“The timing and severity of an influenza pandemic is uncertain, but the danger remains very real,” said Jesse Goodman, M.D., M.P.H., director of FDA’s Center for Biologics Evaluation and Research.
If a pandemic occurs, the approved vaccine may provide early, although limited protection before a vaccine tailored to the pandemic influenza virus strain could be developed and produced.
If a pandemic strain is substantially different from the H5N1 virus contained in the vaccine, or if the pandemic is caused by a strain that does not belong to the H5N1 subtype, the newly approved vaccine would probably not be effective and scientists would need to develop a new vaccine. However, if the pandemic strain is similar but not a perfect match to the vaccine strain, the vaccine may still be useful as studies have shown that the influenza vaccine may provide some immunity against strains that are somewhat different.
Vaccine not available to the public
The manufacturer, Sanofi Pasteur Inc., will not sell the vaccine commercially as yet, but the federal government of the US has purchased the vaccine to include it within the Strategic National Stockpile for distribution by public health officials if needed.
To date, the US Department of Health and Human Services has purchased 13 million doses of the avian influenza vaccine for the stockpile, enough to cover 6.5 million people.
A vaccine against high blood pressure
Scientists at a British pharmaceutical firm have publicised the development of a vaccine against high blood pressure. Protherics in Cheshire has tested the vaccine on people, with success, and has plans for more tests with a new injection that is 10 times better at stimulating the immune system than its original formula.
The vaccine uses a protein found in limpets, a common shellfish, to counteract angiotensin, a hormone produced by the liver that is responsible for raising the blood pressure by narrowing the arteries. It acts by stimulating the body’s immune system to act against the hormone.
The vaccine would require just three injections with a booster every six months and only a few side effects were reported, including 10 per cent of testers complaining of a brief, flu-like illness.
The company is hoping to put its product on the market within five years.
Protherics said this vaccine will be very useful, making life much easier for people who until now had to rely on pills, with possible side effects, to control their blood pressure. Andrew Heath, a company researcher, has commented that “improving compliance in this way could save thousands from life-threatening complications such as heart attacks or strokes.”
Professor Graham MacGregor of Britain’s Blood Pressure Association was enthusiastic about this news as he said: “Raised blood pressure is the most important cause of death from strokes and heart attacks in the UK. If you have to take blood pressure tablets, you have to take them for the rest of your life and some people find that difficult. Finding other and better ways of trying to lower blood pressure, without side effects, would be very welcome”.
Best health wishes,
Dr. Maria Alice