CDC NATIONAL AIDS HOTLINE TRAINING BULLETIN #56 - June 25, 1993
Centers for Disease Control and Prevention

1. "How should we respond to callers regarding newly developed tests for HIV infection? Should we submit questions to CDC for each report of a more effective test being developed? Or should an explanation of the lengthy research period necessary to devise and approve such tests be given to callers, with the assumption that CDC will send a press release if a more effective test is approved?"

Questions on approval/licensure of tests should be submitted to the Food and Drug Administration (FDA) for response. CDC does not have primary responsibility for reviewing data about proposed new HIV antibody, antigen, or virus detection systems. CDC does not prepare press releases on the status of tests that are undergoing research or involved in the FDA-licensing process. Typically, manufacturers and marketers of newly approved test kits prepare press releases. These are not scientific documents and should not be compared with articles published in peer-reviewed journals.

2. "Do you have any information on new tests for infants? We have received calls about "new tests" that allow early detection of HIV infection in infants. These tests seem to be different from the detection of IgA antibodies. A test reported in "AIDSLine" newsletter stated this new test was accurate for a 3-month-old infant, and a report out of Boston claimed to determine infection "a few days after birth."

The "new" tests need more intensive analyses and testing before they are proven to be superior to what is available now. One of the "new" tests for infants uses the standard HIV-antigen test but treats the infant specimens differently. The developers of this "new" test have also obtained results that other researchers have been unable to reproduce.

3. "Please tell us why the range of 12 to 15 months has been changed to 9 to 18 months for infants born to HIV-infected mothers to lose passively acquired maternal HIV antibodies. Is it simply that in tracking these cases CDC has found a broader range? Has this been determined by use of the standard ELISA and Western blot, or by looking for IGA antibodies, or by using PCR or other tests to detect HIV itself?"

While most infants born to HIV-infected mothers lose their passively acquired maternal antibodies at around 9 months, it can take up to 18 months in some infants. This range has been determined by using several methods, such as PCR and viral culture, as well as other experimental diagnostic methods. The change in range does not interfere with the primary diagnosis of HIV infection in infants.

4. "Can injections of immune globulins lead to infection with HIV or even cause false-positive HIV tests?"

No evidence suggests that HBV, HIV, or other viruses have ever been transmitted by immune globulins that are commercially available in the United States. Since April 1985, all plasma units for preparation of all immune globulins have been screened for antibody to HIV, and reactive units are discarded. No instance of clinical illness consistent with transmission of HIV has ever been attributed to receipt of immune globlins, including lots prepared before April 1985. Laboratory studies have shown that the margin of safety based on the removal of HIV infectivity by the fractionation process is extremely high. Some hepatitis B immune globulin lots prepared before April 1985 had detectable HIV antibody (without viral isolation). Low levels of passively acquired HIV antibody were occasionally detected among recipients shortly after administration, but this reactivity did not persist.

5. "Are there any new reasons for false positive results on the ELISA? Callers have asked about several specific possibilities such as having diabetes or being infected with hepatitis, herpes, or mono."

No.

6. "Would you give us information that we can provide callers regarding exact dates of seroconversion, from the studies of persons with verifiable exposure times, e.g., persons with hemophilia, persons who received transfusions from HIV- infected individuals, spouses of both these groups, and occupationally exposed health-care workers? Or should we explain that exact seroconversion times from previous studies cannot assure absolutes?"

Information regarding studies of selected persons who are infected with HIV is available in the medical literature and is constantly being updated. These studies give specific time intervals for seroconversion for the population that was studied. The seroconversion times derived from results of studies of different populations are used to qualify the range of time when a person who is infected may be expected to seroconvert. For instance, a recent study of blood donors screened as seronegative gave a mean infectious window period of 45 days. This finding is consistent with what the Hotline staff is already saying to callers. It would be a serious error to cite exact times and percentages to general callers who believe they may have been exposed to someone with HIV infection and are worried about becoming infected. Some persons may strongly believe that knowing an exact time will reassure them about their risk of infection. However, it is more accurate to give to callers a range of seroconversion times since persons may seroconvert at different intervals.