The US Food and Drug Administration (FDA) announced yesterday that it has approved a vaccine for 2009-2010 seasonal influenza in the United
States and although it does not protect against the new H1N1 swine flu, the federal authority emphasized that it is still important for people
recommended to have the seasonal flu vaccine to make sure they do so.
A vaccine works by stimulating the immune system to produce antibodies. The closer the match between the new antibodies and the strain that the person is later exposed to, the greater the protection they have against being infected by that particular strain. So predicting the exact strain to put in the vaccine is an important part of making sure it is effective.
Every year, experts from the US Centers for Disease Control and Prevention (CDC), the FDA, the World Health Organization (WHO), and other bodies study samples collected from around the world and using various modelling tools try to predict which seasonal flu strains are likely to cause the most illness this winter.
The FDA also consults its Vaccine and Related Products Advisory Committee, and then decides which three strains should go into the next season's vaccines. Once approval is given, manufacturers can start to make the vaccines for the US population.
The vaccines for the 2009-2010 seasonal flu will match the following viruses:
- A/Brisbane/59/2007 (H1N1)
- A/Brisbane/10/2007 (H3N2)
- Afluria (CSL Limited)
- Fluarix (GlaxoSmithKline Biologicals)
- FluLaval (ID Biomedical Corporation)
- Fluvirin (Novartis Vaccines and Diagnostics Limited)
- Fluzone (Sanofi Pasteur Inc)
- FluMist (MedImmune Vaccines Inc)
The federal agency urged all Americans who are recommended to have the seasonal flu virus to make sure they do so. It is still important to protect against seasonal flu, even while the swine flu virus is circulating, they said. Although no vaccine can protect 100 per cent against disease, it is still the best protection available and it prevents many illnesses and deaths, said the agency.
The most vulnerable groups for seasonal flu are the elderly, the sick and children: it is important that these groups get vaccinated, said the FDA, stressing that it was also important that health care workers get vaccinated so they protect themselves and others.
There is always a chance that the predictions don't quite get it right and there is less than an optimal match between the strains in the vaccine and the strains that actually end up circulating in the coming season, but even if that happens, the vaccine can still reduce the severity of illness and help prevent complications.
Figures from the CDC show that between 5 and 20 per cent of Americans get seasonal flu every year, resulting in around 200,000 needing hospital treatment and 36,000 deaths.
Dr Margaret A. Hamburg, the new head of the FDA appointed by Barack Obama, said:
"A new seasonal influenza vaccine each year is a critical tool in protecting public health."
"The approval of this year's seasonal influenza vaccine is an example of the FDA's important responsibility to assure timely availability of vaccine to help protect the health of the American public," she added.
The swine flu appears to have distinct characteristics from seasonal flu. Experts were once predicting that infections in the northern hemisphere would abate during the summer months while the virus circulated in the winter months in the southern hemisphere, but this has not been the case.
Also, as more people are infected, and unfortunately this also means more deaths, it is becoming increasingly apparent that unlike the seasonal flu, the H1N1 swine flu disproportionately affects children and young adults and less so the over 65s.
In the US it is likely that the swine flu campaign will target school age children first and that vaccine for this flu will not be available until October at the earliest said a Wall Street Journal report yesterday.
-- Key facts about seasonal flu vaccine (CDC).
Source: FDA, Wall Street Journal.
Written by: Catharine Paddock, PhD