July 31st, 2009
The CDC has released its recommendations for the forthcoming swine flu vaccine. The vaccine should be available starting in October and the CDC is suggesting prioritizing whom should receive the first doses, since it may take some time to provide enough vaccine for all. Recommended groups are: (from the CDC website):
- Pregnant women because they are at higher risk of complications and can potentially provide protection to infants who cannot be vaccinated;
- Household contacts and caregivers for children younger than 6 months of age because younger infants are at higher risk of influenza-related complications and cannot be vaccinated. Vaccination of those in close contact with infants less than 6 months old might help protect infants by “cocooning” them from the virus;
- Healthcare and emergency medical services personnel because infections among healthcare workers have been reported and this can be a potential source of infection for vulnerable patients. Also, increased absenteeism in this population could reduce healthcare system capacity;
- All people from 6 months through 24 years of age
- Children from 6 months through 18 years of age because we have seen many cases of novel H1N1 influenza in children and they are in close contact with each other in school and day care settings, which increases the likelihood of disease spread, and
- Young adults 19 through 24 years of age because we have seen many cases of novel H1N1 influenza in these healthy young adults and they often live, work, and study in close proximity, and they are a frequently mobile population; and,
- Persons aged 25 through 64 years who have health conditions associated with higher risk of medical complications from influenza.
You’ll note that one of the usually recommended group, persons aged 65 and older, has been left off the list. It appears that this age group is having fewer problems with the current swine flu strain. Perhaps their immune systems have seen a similar strain in the past.
Dr. O
July 30th, 2009
My last post before leaving for Africa dealt with Xolair and the allergic response. In it I mentioned that there are some risks associated with Xolair use. While I was away, the FDA issued a safety warning on Xolair based on review of a post marketing study. Rather than paraphrase, I’ll just copy their statement:
“The interim data, submitted by the manufacturer of Xolair (Genentech), suggest a disproportionate increase in ischemic heart disease, arrhythmias, cardiomyopathy and cardiac failure, pulmonary hypertension, cerebrovascular disorders, and embolic, thrombotic and thrombophlebitic events in patients treated with Xolair compared to the control group of patients not given the drug…….
FDA is not recommending any changes to the prescribing information for Xolair and is not advising patients to stop taking Xolair at this time. Until the evaluation of the EXCELS study is completed, healthcare providers and patients should be aware of the risks and benefits described in the prescribing information, as well as the new information from the ongoing EXCELS study that may suggest a risk of cardiovascular and cerebrovascular adverse events.
This early communication is in keeping with FDA’s commitment to inform the public about ongoing safety reviews of drugs. FDA has not made any conclusions regarding these data.”
So there you have it. A possibility of an additional risk factor for Xolair without mention of risk percentage or types of events. Even though they’re not sure it’s real, they’re letting us know to keep a close eye on this in the near future.
Dr. O
July 29th, 2009
Jambo. I’m finally back, both physically and mentally, from my three week break. I was with the family on safari in Kenya and Tanzania. It was an amazing experience. Travel really is one of the best teachers.
Needless to say, there’s been some catch-up at work. I’ll be back to posting soon once I can get everything squared away.
Dr. O
July 2nd, 2009
In my last post, I touched on improvements in treating the severest pediatric asthmatics. One thing I noticed in reviewing the info for the post was that 10% of the current study patients were on a medication called Xolair. Xolair, or omalizumab, is a new class of medication that blocks the acute allergic response from occurring. It is only indicated for use in a very few people: severe asthmatics with allergies and an elevated IgE level. This is a little complicated, so some background is helpful.
How Xolair works, image courtesy of NEJM
IgE is an antibody. Antibodies are proteins the immune system makes to help fight off infections. There are three other main antibodies besides IgE: IgG, IgA, and IgM. IgE is the allergy antibody. In the cartoon above, it is represented by the blue Y-shaped figures. One end of IgE binds to allergens like ragweed pollen or cat dander and the other end binds to cells like the mast cell;. When two IgE molecules bound to a mast cell also bind to the same allergen they crosslink. Crosslinking is the signals the mast cell to go to work, which it does by essentially exploding and releasing all kinds of nasty chemicals that make you sneeze, wheeze, and get hives.
Omalizumab is a hybridized, murine, monoclonal antibody directed at the Fc portion of human IgE. Got it? In English, that means that omalizumab, the red Y-shape, latches on to the end of IgE that normally touches the mast cell and prevents it from binding to the mast cell. If IgE can’t bind to the mast cell, then it can’t crosslink and the mast cell is effectively neutralized. It’s like taking the bullets out of a gun.
Studies looking at omalizumab use in severe asthmatics have shown reduction in medication use, improvement in symptoms, and improvement in quality of life. In my own experience, the response has been black-and-white. Some people have made remarkable improvements on omalizumab and some haven’t responded much at all.
Omalizumab is not a cure-all. It is an injectable medication that has to given every 2-4 weeks. There are some risks associated with its use as well. Mostly, it’s incredibly expensive. A 2007 study gives an average monthly cost of $1300. I’m conservative about recommending it to people and in the coming healthcare environment, I’m not sure what its fate will be. That being said, in people with frequent severe exacerbations, ED visits, and/or hospitalizations as well as those on continuous or near continuous oral corticosteroids for asthma, omalizumab can make a huge difference. If you’re a severe asthmatic, ask your doctor about omalizumab/Xolair.
Dr. O
