Considerations in prioritizing influenza vaccine in HIV-infected patients

Date of Report: 10/29/2004
Author:  Amy Kindrick, MD, MPH,
Source: National Clinicians' Consultation Center

Because the influenza vaccine is in short supply this year, clinics and care providers may be responsible for making decisions about which of their HIV patients will receive vaccine and which will not. The CDC Interim Influenza Vaccination Recommendations, 2004-05 Influenza Season ¹ include adults with underlying chronic medical conditions (such as HIV) in their "Priority Groups for Influenza Vaccination". In this current setting of limited supply, however, the CDC has no plans to rank the groups for which vaccine is recommended; further, there probably will not be any federal or state guidance about how to prioritize various individuals within or between the groups.

The literature on influenza vaccination does not support firm distinctions between different risk groups. While it seems reasonable that, for example, seniors and people with chronic lung disease should take priority over healthy HIV-infected patients, the data are not sufficient to guide these kinds of triage decisions, and a significant measure of "clinical judgment" must be included. The following comments are intended as one clinician's opinion.

For patients with HIV infection, the literature on the effects of influenza infection and on the efficacy of influenza vaccine does not fully inform triage decisions about vaccination. ^2,3,4,5,6 In general, patients with HIV infection have not been shown to have higher influenza complication rates than HIV-negative patients, but it is possible that subgroups of HIV-infected patients are at increased risk for complications. Also, some individual differences within categories of HIV-infected patients may be greater than differences between categories. HIV-infected patients with comorbid conditions that put them at higher risk of complications from influenza, such as chronic cardiovacular or pulmonary disorders, should possibly be prioritized above healthy HIV-infected patients, regardless of CD4 counts⁷. Overall, while clinical criteria should inform triage decisions, it probably is reasonable to stratify healthy HIV-infected patients based on CD4 count.

Consider prioritizing healthy HIV-infected vaccine candidates who have no other vaccine indications as follows:

	1. Patients with current CD4 200-500 cells/mm3 (on or off antiretroviral medications (ARVs)) Rationale: Very likely to mount an immunologic response to vaccine and possibly at increased risk for complications if they contract influenza
	2. Patients with current CD4 < 200 cells/mm3 (on or off ARVs) Rationale: Less likely to mount a protective immunologic response but at increased risk for complications and therefore more likely to benefit if they do respond to vaccine
	3. Patients with current CD4 > 500 cells/mm3 but nadir CD4 < 200 cells/mm3 or AIDS-defining condition Rationale: Likely to mount a protective immunologic response and possibly at increased risk for complications
	4. Patients with current CD4 > 500 cells/mm3 and nadir CD4 > 200 cells/mm3 and no AIDS-defining condition Rationale: Most likely to mount a protective immunologic response but least likely to have complications if they contract influenza

References

1.		The CDC interim flu vax guidelines can be reviewed at http://www.cdc.gov/flu/protect/pdf/whoshouldget.pdf (Of particular note, since the shortage, the lower age range for healthy adults recommended to receive vaccine has been raised to 65 years.)
2.		Radwan HM, Cheeseman SH, Lai KK, Ellison IR. Influenza in human immunodeficiency virus-infected patients during the 1997-1998 influenza season. Clin Infect Dis 2000; 31:604-6.
3.		Golden MP, Sajjad Z, Elgart L. Influenza and human immunodeficiency virus infection: absence of HIV progression after acute influenza infection. Clin Infect Dis 2001; 32:1366-70.
4.		Zanetti AR, Amendola A, Besana S, Boschini A, Tanzi E. Safety and immunogenicity of influenza vaccination in individuals infected with HIV. Vaccine 2002; 20 Suppl 5:B29-32.
5.		Skiest DJ, Machala T. Comparison of the effects of acute influenza infection and Influenza vaccination on HIV viral load and CD4 cell counts. J Clin Virol 2003; 26:307-15.
6.		Skiest DJ, Kaplan P, Machala T, Boney L, Luby J. Clinical manifestations of influenza in HIV-infected individuals. Int J STD AIDS 2001; 12:646-50.
7.		Prevention and Control of Influenza, Recommendations of the Advisory Committee on Immunization Practices (ACIP) . MMWR April 25, 2003; 52(RR08); 1-36