Swine Flu Update
by ilene - November 15th, 2009 12:17 am
Cliff Notes for “Swine flu: One Killer virus, three key questions.”
By Ilene
Brendan Maher and Declan Butler, authors of a recently published Nature article “Swine flu: One killer virus, three key questions,” set out to answer three questions about the H1N1 virus. Here’s what they found.
How does it kill?
Sherif Zaki, head of the infectious-disease pathology branch at the Centers for Disease Control, discusses his team’s observations from their pathological studies.
1. The H1N1 virus penetrates deep into the alveoli (the terminal air sacs in the lungs). In contrast, the seasonal flu viruses tend to infect cells higher in the upper airways. This deep penetration is reminiscent of the action of the H5N1 avian flu virus. Zaki commented: “[H1N1] is like avian flu on steroids.” Why might this be?
Zaki says that his observations fit well with recent research looking at the mechanism of infection. A group led by Mikhail Matrosovich at Philipps University Marburg in Germany and Ten Feizi at Imperial College London studied sialyl glycans, glycoproteins that the flu virus binds to in order to gain entry to human cells. Although seasonal strains of H1N1 bind mostly to versions of the glycoproteins known as α2-6, the researchers found that the new pandemic H1N1 can also bind to a version called α2-3, which is found in greater proportion in the lower respiratory tract.
2. In patients who have died, co-infection was common with H1N1. Zaki’s group observed infection with bacteria such as Staph aureus or Streptococcus pneumoniae in about a third of the fatal swine-flu cases. However, in the remaining two thirds of fatal cases, the virus was lethal alone. The damage seen in the lungs is characterized as ‘diffuse alveolar damage,’ reflecting a very difficult to treat state of respiratory distress syndrome. According to Zaki’s research, about 90% of the fatal cases had some underlying medical condition.
Zaki expects the number of flu cases to increase as the flu season “ramps up.”
How does H1N1 spread?
Brendan Maher visited Peter Palese’s laboratory at Mount Sinai School of Medicine where testing for how the viruses spread is being carried out. Researchers John Steel and Anice Lowen compared the transmissibility of H1N1 to that of seasonal flu using a guinea pig model. Their data indicate that the H1N1 virus transmits as efficiently as seasonal flu viruses, which is consistent with real-world data showing…
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Double-Edged Sword: Swine Flu and Vaccines
by ilene - November 6th, 2009 1:26 am
By guest author Terry Doherty and Ilene, your editor
Terry Doherty is the Research Program Coordinator in the Depts of Biomedical Sciences and Academic Affairs at Cedar Sinai in Los Angeles, California.
Double-Edged Sword: Swine Flu and Vaccines
There’s plenty that is unknown about the swine flu and the swine flu vaccine. If searches on the internet are any indication, deciding whether or not to be vaccinated may be a tough, emotionally charged decision for many people. So how – without having the background to write a swine flu grant proposal, conduct the research, and get the thing published in the New England Journal of Medicine – do we decide whether or not to get a swine flu shot?
One way is to attempt to evaluate and weigh the risks of the vaccine against the risks of the flu. That is how I approach the subject, but it’s easier said than done. As is often the case with medical interventions, the risks are not fully known. And even if we could carefully assess the risks, our underlying assumptions may be wrong. Percent risks are averages collected by studying large populations. We may not be one of the statistical average. Then there are the gaps in the available data, and own biases and belief systems. Our view of the world affects our analysis and often we are not even aware of how large of an effect those biases may play.
In Vaccine War: Autism, Flu and Science, TIME, Maia Szalavitz discusses how emotion and biases play a large part in our risk-benefit assessments:
Just in time for the national roll-out of the new H1N1 flu vaccine, Wired Magazine and the Atlantic have weighed in on the ongoing vaccine war: Wired has a profile of Paul Offit, a vaccine researcher and pediatrician who has consistently spoken out in favor of vaccination and pointed to the lack of evidence linking vaccines and autism; the Atlantic checks in with a piece questioning the science suggesting that flu vaccines and antiviral drugs prevent people from dying.
Both articles have elicited heated debate all over the Web: Amy Wallace, who wrote Wired’s piece, excerpted below, has received vitriolic criticism and attacks from vaccine opponents, setting records for page views…
This debate over vaccination doesn’t seem likely to end any time soon. For critics, vaccines…
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