Swine Flu and Immune-Suppressing Drugs

Mark Borigini, M.D. Health Pro
  • Many medications prescribed for rheumatoid arthritis can weaken the immune system, including prednisone, methotrexate, and, of course, the biologic agents such as Humira, Enbrel and Remicade, to name but a few.  The use of these medications can make a patient more susceptible to the H1N1 virus (the so-called swine flu) and the regular seasonal influenza.  And if a patient on an immunosuppressive drug does contract such a viral illness, there is a much higher risk of developing more severe-and thus more life-threatening-disease.


    The key is to avoid contracting seasonal influenza or the swine flu H1N1 virus.  This can be best achieved through frequent hand washing, having those around you cover their mouths when they cough or sneeze, and avoiding individuals known to be ill, including family members or acquaintances in social gatherings.  The H1N1 virus spreads mainly from person to person through coughing or sneezing by people with the virus.  However, individuals can also be infected by touching objects contaminated with the virus, and then in turn touching her mouth or nose.  Therefore, try also to get out of the habit of touching your mouth or nose this season.

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    A recent article in The Lancet Infectious Diseases journal examined how influenza affects immunosuppressed individuals with HIV/AIDS or cancer, transplant patients and patients on dialysis or steroids.  Rheumatoid arthritis patients per se were not studied, but it is my opinion that the conclusions can be extrapolated to those rheumatoid arthritis patients taking immunosuppressive medications.


    The article found that there is little research on using vaccination to prevent influenza in immunosuppressed people.  Studies of HIV/AIDS patients show a lower antibody response to vaccination, but studies also show that vaccination results in fewer and less severe cases of flu in these patients.  Larger studies are needed to know how useful vaccination is for these patients.


    Transplant patients have higher flu infection rates due to the immunosuppressant drugs they take to prevent rejection of the transplanted organ.  Cancer patients on chemotherapy also experience significant immunosuppression, the data showing that up to 33% of these patients contract flu.  Patients taking cor€ticosteroids such as prednisone appear to have a positive response to flu vaccination.


    The authors of this paper conclude that most immunosuppressed populations have a greater risk of influenza-associated complications.  These patients may have an impaired antibody response to vaccination, thus rendering the vaccine less protective:  One study found that patients on cancer chemotherapy had a poor antibody response to vaccination, whereas dialysis patients and transplant patients achieved fairly good antibody responses when vaccinated.


    While most immunosuppressed patients can be safely vaccinated, it is not known whether all will develop significant immunity to ward off swine flu or traditional influenza.  Rheumatoid arthritis patients in particular have not been well-studied. 


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    Some patients have asked whether the H1N1 vaccine itself poses a danger to immunosuppressed patients.  Thus far, this does not appear to be the case.


    Interestingly, scientists have been exploring the possibility that drugs that affect the immune system in rheumatoid arthritis might one day be used to fight both traditional seasonal flu and the H1N1 swine flu.  A group of lab mice were treated with the biologic drug Orencia after being given a lethal dose of the typical seasonal influenza A virus.  Researchers found that 80% of the treated mice lived, compared to 50% of those not treated, according to the data presented in the June 1 issue of The Journal of Immunology.  Researchers also injected mice with T-cells that had been programmed to react to an H1N1 strain of influenza A virus. Those mice given Orencia cleared the virus more quickly, were less ill, and recovered more rapidly.


    It appears that Orencia enabled infection-fighting T cells to fight off the infection. This is an exciting finding, as drugs such as Orencia would have the advantage of being effective against different strains of the flu virus, as the immune system is being targeted, not the virus.  On the other hand, an annual vaccine is only effective against certain viral strains.


    Obviously, humans are not mice, and more work would have to be done to ensure safety in humans infected with influenza.  In the meantime, I think we all have to assume that many of the drugs used to treat rheumatoid arthritis can weaken the immune system in humans, resulting in more susceptibility to both seasonal influenza and H1N1, and the potential for more severe disease due to the weakened state of the immune system.


    Talk to your doctor about whether you should be vaccinated against both the seasonal flu virus and the swine flu H1N1 virus.



    See up-to-date information about H1N1 virus on our swine flu H1N1 virus page.


Published On: September 02, 2009