Thank you for your inquiry and your comments. You are of course correct. There is a second issue when one deals with live viral vaccines. One needs to be concerned about immune suppression of the host, not only in regards to their ability to manifest an immune response, but also their ability to prevent viral spread.
The defenses against live viral vaccines are in many instances dependent on T cell immunity and corticosteroids are more suppressive of T cell immunity than they are of antibody production. For the sake of our readers, I have copied below the recommendations from the CDC in regards to the use of corticosteroids in patients receiving live viral vaccines.
"Steroid therapy usually does not contraindicate administration of live-virus vaccines when such therapy is short term (less than 2 weeks); low to moderate dose; long-term, alternate-day treatment with short-acting preparations; maintenance physiologic doses (replacement therapy); or administered topically (skin or eyes), by aerosol, or by intra-articular, bursal, or tendon injection. The exact amount of systemic corticosteroids and the duration of their administration needed to suppress the immune system of an otherwise healthy child are not well defined. The immunosuppressive effects of steroid treatment vary, but many clinicians consider a dose equivalent to either 2 mg/kg of body weight or a total of 20 mg/day of prednisone as sufficiently immunosuppressive to raise concern about the safety of immunization with live-virus vaccines. Corticosteroids used in greater than physiologic doses also may reduce the immune response to vaccines. Physicians should wait at least 3 months after discontinuation of therapy before administering a live-virus vaccine to patients who have received high-dose, systemic steroids for greater than or equal to 2 weeks."
Source: Recommendations of the Advisory Committee on Immunization Practices (ACIP): Use of Vaccines and Immune Globulins in Persons with Altered Immunocompetence.
In addition, your comment regarding the different recommendations is also valid. For example, in some live viral vaccines (e.g., rabies), the admonition against the simultaneous administration of corticosteroids is even greater (see quote copied below).
"Rabies Vaccine, Corticosteroids, other immunosuppressive agents, and immunosuppressive illnesses can interfere with the development of active immunity and predispose the patient to developing rabies if exposed. Immunosuppressive agents should not be administered during postexposure therapy, unless essential for the treatment of other conditions. When rabies postexposure prophylaxis is administered to persons receiving steroids or other immunosuppressive therapy, it is especially important that serum be tested for rabies antibody to ensure that an adequate response has developed."
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.