Date: August 8, 1995
From: Director, Center for Biologics Evaluation and
Research (CBER)
Subject: Recommendations for Donor Screening with a Licensed
Test for HIV-1 Antigen
To: All Registered Blood and Plasma Establishments
INTRODUCTION
This memorandum provides the recommendations of the Food and
Drug Administration (FDA) on the implementation of donor
screening tests for human immunodeficiency virus, type 1 (HIV-
1) antigen(s).  The attached recommendations supersede
previous FDA recommendations contained in a memorandum of
October 4, 1989, following licensure of the first test for
HIV-1 antigen(s). 
BACKGROUND
On March 23, 1989, the Blood Products Advisory Committee
(BPAC) of the Food and Drug Administration recommended
licensure of a test for the detection of HIV-1 antigen(s) in
serum or plasma (HIVAG-1TM, Abbott Laboratories, North Chicago,
Illinois) as an aid in determining the diagnosis and prognosis
of patients with HIV-1 infection, but not as a screening test
for blood and plasma donors.  Consistent with the BPAC
recommendation, FDA approved the test with the following label
restriction, "This test is not intended as a screen for
donated blood or plasma."
The rationale for this decision was the absence of known HIV
transmission by plasma derivatives since 1987, and the lack of
detection of antigen positive, antibody negative donations in
large scale donor screening studies conducted both within the
United States and Europe1,2.  These and other studies were
interpreted to imply that detection of HIV-1 antigen in the
absence of antibody would be a very rare event in U.S. donor
screening, although the frequency of detection could not be
estimated.  Based on the available data, FDA did not approve 
HIV-1 antigen testing for routine donor screening.
Recently, the role of HIV-1 antigen testing in the donor
setting has been reconsidered for several reasons.  First, there have been four documented instances of HIV-1
transmission by HIV-1  antigen positive blood donations from
three HIV-1 antibody negative donors.  All four cases were
identified by retrospective analysis of stored samples from
previous donations of the  seroconverting donors.3-5    
Second, there have been more recent estimates of the residual
risk of HIV transmission by screened blood and the efficacy of
antigen testing to detect seronegative, infectious donations. 
Based on studies involving 19 blood centers within the U.S.,
Lackritz, et al. estimated that the current HIV risk per unit
is 1:440,000 - 1:640,0006, compared with risk estimates in
1989 of 1:38,000 to 1:150,0007,8.  A risk of 1:440,000
corresponds to approximately 41 cases of recipient exposure
per year out of 18 million units transfused.  
Busch, et al. estimated that the antibody negative infectious
"window period" is approximately 22-25 days for screening with
combination assays for antibodies to HIV-1 and HIV-2 as
determined in 81 seroconverting homosexual men or injection
drug users.9   The authors estimated that HIV antigen
screening could reduce the "window period" by about 6 days
while testing by polymerase chain reaction (PCR) for RNA could
reduce the "window period" by about 11 days.  As a result, it
is estimated that donor screening by HIV-1 antigen can be
expected to prevent up to 25% of the current "window period"
cases by detection of about 5-10 cases of antigen-positive/
antibody-negative collections per year.10  Screening for HIV-1
antigen also may contribute to the safety of plasma
derivatives by reducing the frequency of HIV contamination in
plasma pools for fractionation.
In September, 1994, FDA sponsored a "Conference on the
Feasibility of Genetic Technology to Close the HIV Window in
Donor Screening" to address the value of direct viral
detection in donor screening.  For a variety of reasons, the
majority of participating experts expressed the opinion that
genetic techniques, although capable of HIV-1 detection prior
to seroconversion, were not ready for use in mass screening. 
This meeting did, however, spark renewed interest in
considering other direct viral detection methods for donor
screening, such as HIV-1 antigen testing, as an interim
measure to further reduce the current low risk of HIV-1
transmission through transfusions of blood and blood products. 
To further address direct viral detection methods, FDA brought
2 the issue of donor screening for HIV-1 antigen to a public
meeting of the BPAC on June 23, 1995.  The BPAC members agreed
unanimously that the current estimates of HIV-1 prevention by
antigen screening of blood donors are sufficient to determine
efficacy of test kits for donor screening.  After hearing the
most recent available data on HIV-1 risk in the blood supply,
the estimated efficacy of antigen screening, and other issues
bearing on a risk/benefit assessment  (e.g. "magnet effect" of
high risk donors seeking testing, cost analysis, etc.), 9 of
the 15 BPAC members present were of the opinion that donor
screening for HIV-1 antigen by candidate test kits is not
likely to provide a significant public health benefit which
outweighs the potential risks.  
After considering the available information and the opinions
of the BPAC members, FDA now is recommending that blood
establishments should implement donor screening for HIV-1
antigen using licensed tests that are approved for this
indication.  FDA is recommending implementation of HIV-1
antigen screening because of the benefit that it will provide
to a small number of blood product recipients, as a partial
preventive measure against the possibility of any increase in
HIV-1 "window period" donations and to decrease the virus
burden in plasma pools for fractionation.  Because HIV-1
antigen testing will only reduce but not eliminate the
residual risk of HIV-1 from transfusion, the FDA regards such
screening as only an interim measure pending the availability
of better technology for this purpose.  FDA encourages
continued development of new methods to further reduce the
risk of HIV transmissions in the "window period".
Although currently there are no tests for HIV-1 antigen(s)
approved for donor screening, FDA is issuing recommendations
on donor screening for HIV-1 antigen(s) in advance of the
availability of such tests in order to provide blood and
plasma establishments with maximum time to prepare for this
testing.
Questions concerning these recommendations may be directed to
the Division of Transfusion Transmitted Diseases, FDA/CBER
(HFM-310), 1401 Rockville Pike, Rockville, MD 20852; FAX:
(301) 594-6989.
                             
    Kathryn C. Zoon, Ph.D.
3 RECOMMENDATIONS FOR DONOR SCREENING
WITH A TEST FOR HIV-1 ANTIGEN(S)
TERMINOLOGY
The following terms apply to HIV-1 antigen testing:
Initially reactive:  Initial EIA test is reactive.
Repeatedly reactive: One or both duplicate EIA retests is
(are) reactive.
NEGATIVE: Initial EIA test is not reactive;
or, initial EIA test is reactive
and both duplicate EIA retests
are not reactive.
POSITIVE: EIA test is repeatedly reactive
and the neutralization test is
positive (neutralizing).
INDETERMINATE: EIA test is repeatedly reactive
and the neutralization test is
either negative (non-
neutralizing) or indeterminate
(invalid). 
Donor specimens that are repeatedly reactive in the screening
assay which are neutralizing according to the criteria set
forth by the test kit manufacturer are considered POSITIVE for
HIV-1 antigen(s).  Donor specimens that are repeatedly
reactive in the screening assay, but which are negative in the
neutralization test are unlikely to contain HIV-1 antigen(s). 
However, they should not be regarded as negative because of
the possible occurrence of false-negative neutralization
tests.  Therefore, specimens that are repeatedly reactive in
the screening assay but which are negative or indeterminate
(invalid) by the criteria set forth for neutralization by the
manufacturer should be considered INDETERMINATE.  
    
RECOMMENDATIONS  
A. Implementation of Donor Screening for HIV-1 Antigen(s)
4 1. All donations of Whole Blood, blood components,
Source Leukocytes and Source Plasma should be
screened for HIV-1 antigen(s) by an FDA licensed
test labeled specifically for use in donor
screening.  FDA believes that this recommendation
should be implemented within three months of the
commercial availability of the first such test. 
Following the date of implementation, only units
from donors found negative on HIV-1 antigen
screening and acceptable by all other criteria
should be released for use in transfusion or for
further manufacturing into injectable products. 
Antigen testing should be performed in addition to
required testing for antibodies to HIV-1 and HIV-2
(see previous FDA recommendations of April 1992).  
  
2. Within three months of the commercial availability
of the first FDA licensed HIV-1 antigen test labeled
specifically for use in donor screening, all
inventoried units of Whole Blood, blood components,
Source Leukocytes and Source Plasma available for
release should be screened for HIV-1 antigen(s).
         
3.  Blood establishments should cooperate with
consignees to insure that inventoried within-date
units intended for use in transfusion which were
distributed prior to test implementation are either
replaced with screened units or else tested for HIV-
1 antigen(s) as soon as feasible.
      
B. Disposition and Labeling of Units 
1. Units from Donations Negative for HIV-1 Antigen 
a. Products for transfusion:  The instruction
circular should state, consistent with 21 CFR
606.122(h), that the product was prepared from
blood that was negative in a screening test for
HIV-1 antigen(s).  Blood establishments should
maintain a record of the date of implementation
of testing for HIV-1 antigen(s).      
b. Products for further manufacturing use:  The
container label should bear the statement,
"Negative by a test for HIV-1 antigen(s)" or an
equivalent statement.  The statement regarding
5 anti-HIV test results, HBsAg test results [21
CFR 640.70(a)(8)] and anti-HCV test results may
be combined with the statement regarding the
HIV-1 antigen test results.  For example, the
statement could be: "Negative by tests for HIV-1
antigen(s), antibodies to HIV and HCV, and
nonreactive for HBsAg."
2. Units from Repeatedly Reactive Donations
a. Units of Whole Blood, blood components, Source
Leukocytes and Source Plasma obtained from a
donor whose blood sample is found to be
repeatedly reactive using a licensed screening
test for HIV-1 antigen(s) should be quarantined
to prevent inappropriate release.  Quarantined
units should either be destroyed or not used for
transfusion or for further manufacturing into
injectable products, except as approved by the
Director, CBER.  
It is recommended that blood or blood components
be withheld from autologous use if HIV-1 antigen
screening tests are repeatedly reactive. 
However, such products may be distributed for
autologous use only provided that: (1) a
written, signed and dated request is received
from the patient's physician; (2) written
permission is obtained from the transfusion
service to receive the products (if applicable);
(3) the transfusion service takes responsibility
for ensuring that there is documented
verification of the accurate identity of the
transfusion recipient; and (4) the products are
labeled "BIOHAZARD" and "FOR AUTOLOGOUS USE
ONLY."
b. Establishments which intend to ship for further
manufacture into non-injectable products, units
which are inadvertently collected from donors
who test repeatedly reactive for HIV-1
antigen(s) should use FDA approved labels and
maintain shipping documents for review at the
time of FDA inspection. 
c. There are few approved uses of HIV-1 antigen
repeatedly reactive products other than for
6 research and the manufacture of reagents
required for HIV testing.  The intentional
collection of repeatedly reactive units for use
in such products, as well as manufacture,
special labeling and distribution, requires
advance approval of a specific license
application or supplement by the Director, CBER. 
d. Units which are not destroyed should be labeled
with four cautionary statements as follows:
"NOT FOR TRANSFUSION" [21 CFR 606.121 (f)]
"BIOHAZARD"
"Reactive by a test for HIV-1 antigen(s).  The
risk of transmission of HIV is present."
and
"For further manufacture into in-vitro
diagnostic reagents for which there are no
alternative sources" or "For laboratory research
use only."
3. Untested Blood and Blood Components
In the case of rare products which cannot be tested
because they were placed in frozen storage before
licensed HIV-1 antigen tests suitable for donor
screening were available and for which there is no
available substitute product (e.g. rare red blood
cell phenotypes), a statement such as one of the
following should be applied:
"CAUTION: This product was prepared before testing
for HIV-1 antigen(s) was implemented and the
subsequent HIV status of the donor is not known," or
"This product was prepared before testing for    
  HIV-1 antigen(s) was implemented.  The donor
was tested on (Date), more than eight weeks
after the date of collection, and was found to
be NEGATIVE for HIV-1 antigen(s) and for
antibodies to HIV-1 and HIV-2."
7 C. Donor Deferral 
Donors of Whole Blood, blood components, Source
Leukocytes and Source Plasma whose blood specimens are
found to be repeatedly reactive using a licensed
screening test for  HIV-1 antigen(s) should be further
tested by a neutralization procedure according to the
manufacturer's instructions in the package insert in
order to determine their deferral status.  The results of
a neutralization test may also be useful in donor
notification and counseling.  The same specimen as used
for initial screening or another specimen from the same
collection should be used for this additional, more
specific, testing as long as the specimen has been stored
properly as outlined in the package labeling for the HIV-
1 antigen(s) detection kit being used.
1. Donors whose blood samples are POSITIVE for HIV-1
antigen(s) based on the neutralization test should
be permanently deferred.
2. Donors whose blood samples are INDETERMINATE based
on the neutralization test or untested by
neutralization should be temporarily deferred from
donation for a minimum of eight weeks.  If a
temporarily deferred donor re-donates or is
otherwise retested after a period of at least eight
weeks:
a. The donor can automatically be reinstated and
any current collection may be used if all donor
screening tests (including HIV antigen) are
performed and found NEGATIVE, and the donor
meets all other suitability criteria.
b. The donor is permanently deferred if the
screening test for HIV antigen is repeatedly
reactive on any subsequent evaluation or
donation, regardless of the result of the
neutralization test. 
     
3. The names of donors with repeatedly reactive
screening test results should be entered on the
deferral registry in such a way that they can be
identified as being permanently or temporarily
deferred [21 CFR 606.160 (e)].  Confidentiality of
8 the results should be protected.  It should be
ensured that products from unsuitable donors are
excluded from use without disclosing the reason to
unauthorized personnel.  The deferral system should
also ensure that products obtained from subsequent
donations of unsuitable donors will not be
distributed [21 CFR 606.160 (e)].
D. Public Health Service (PHS) Recommendations for Donor
Notification and Counseling
In a blood or plasma donor population, the vast majority
of repeatedly reactive HIV-1 antigen screening results
are expected to be falsely positive.  All samples
repeatedly reactive for HIV-1 antigen(s) by EIA should be
promptly tested by the neutralization test to determine
whether the donor is truly POSITIVE for HIV-1 antigen(s). 
Because of the potential deterioration of HIV antigen(s)
on sample storage, care should be exercised to follow the
sample storage and time restrictions specified in the
test kit package insert.  The neutralization test should
be done before informing donors of their repeatedly
reactive test results.  Donor notification should contain
information about the significance of the test results
and suggest medical follow-up. 
Individuals with POSITIVE results based on an HIV-1
antigen neutralization test are presumed to be infected
with HIV. Donors with POSITIVE results on an HIV-1
antigen neutralization test should be notified and
counseled regarding evidence of HIV infection.  Such
results should be confirmed by medical follow-up
including testing for antibodies to HIV-1 and HIV-2 after
a period of at least eight weeks.  
The HIV status of individuals with INDETERMINATE results
is not clear and the donors should be further evaluated. 
Because of the potential for the rapid degradation of
HIV-1 antigen in improperly stored samples, clarification
of the neutralization test may be obtained by testing a
fresh specimen or by testing the donor for antibodies to
HIV-1 and HIV-2 after a period of at least eight weeks. 
If INDETERMINATE results persist on retesting after at
least eight weeks in the absence of seroconversion to
HIV-1 or HIV-2, the individual may be considered negative
for purposes of counseling.  However, these individuals
9 should be advised that they are no longer acceptable as
donors because of their test results.  
E. Exclusion/Retrieval of Potentially Contaminated Units
from    Prior Collections and Notification of Consignees
  
See FDA's memorandum dated April 23, 1992 for FDA
recommendations regarding units from prior collections
from donors found repeatedly reactive for antibodies to
HIV-1 or HIV-2.  FDA further recommends the quarantine of
previously collected units of Whole Blood, blood
components, Source Leukocytes or Source Plasma from any
person who tests repeatedly reactive by a screening test
for HIV-1 antigen(s) in the absence of a repeatedly
reactive screening test(s) for antibodies to HIV-1 and
HIV-2. 
 
1. Retrieval and Quarantine of Prior Collections  
Blood centers should within 72 hours identify and
quarantine all in-date units collected within the
three months prior to the donor's repeatedly
reactive screening test for HIV-1 antigen(s).  The
consignees of such units should be notified so that
the units that they hold also can be quarantined. 
The quarantined units should not be transfused or
used in further manufacturing pending the result of
subsequent donor testing.  For plasma for
fractionation, the retrieval can be limited to units
which have not already been pooled or further
processed.
  2. Release of Units from Quarantine
Previously collected units may be released from
quarantine if the donor subsequently qualifies for
reentry based on negative tests for both HIV-1
antigen(s) and antibodies to HIV-1 and HIV-2 at
least eight weeks after the repeatedly reactive
collection.  If retesting of the donor is not
performed within six months of the repeatedly
reactive result, any quarantined units from prior
collections should be destroyed or relabeled with
four cautionary statements as follows:
"NOT FOR TRANSFUSION" [21 CFR 606.121 (f)]
10 "BIOHAZARD"
"This product was collected from a donor later
known to be reactive for HIV-1 antigen(s).  The
risk of transmission of HIV is present."
and
"For further manufacture into in-vitro
diagnostic reagents for which there are no
alternative sources" or "For laboratory research
use only."
F. Notification of Consignees of Neutralization Test Results 
Notification of consignees of the results of
neutralization tests for donors with repeatedly reactive
screening tests for HIV-1 antigen(s) should be performed
so that transfusion services can carry out recipient
tracing and notification through the attending
physicians.  This testing and notification should be
completed as soon as feasible (within two weeks if
possible) following the repeatedly reactive screening
test.  (Unless the neutralization test is completed
within the maximum storage time allowed for the test kit
being used, a fresh specimen of blood should be used for
neutralization testing.)  It is not intended that
consignees should initiate recipient tracing based only
on a repeatedly reactive donor screening test result for
HIV-1 antigen(s) prior to the availability of the result
of the neutralization test.
For cases in which units were obtained from the donor
during the three month period prior to the repeatedly
reactive donation, blood centers should notify consignees
of the results of a POSITIVE test on the donor's current
sample, based on additional testing by neutralization.    
If the test result is INDETERMINATE based on a
neutralization test that is negative (non-neutralizing)
or indeterminate (invalid), but the test sample has not
been stored appropriately according to the instructions
in the package insert, a fresh sample should be obtained
as soon as possible and tested by both the screening EIA
and neutralization test for HIV-1 antigen(s) prior to
11 consignee notification.  
If the neutralization test is INDETERMINATE, based on a
fresh or properly stored sample, the consignee should be
notified.  However, a judgement by the medical director
should be made regarding the potential benefits of
recipient tracing prior to resolution of the HIV status
of the donor through follow-up testing for antibodies to
HIV.
Whenever possible, a follow-up sample from the donor at
least eight weeks later should be tested for antibodies
to HIV-1 and HIV-2 to rule-in or exclude HIV infection. 
The recommendations contained in this memorandum may be
implemented without prior approval from FDA.  Licensed
establishments implementing these recommendations should
submit by official correspondence a statement to their product
license file indicating the date that revised standard
operating procedures consistent with these recommendations
have been established and implemented.  If an establishment
believes that an alternative approach would provide equivalent
protection, the establishment is invited to discuss the
approach with FDA for FDA's evaluation.
12 1. Alter HJ, JS Epstein, SG Swenson, et al.  Prevalence of human
immunodeficiency virus type 1 p24 antigen in U.S. blood donors
- an assessment of the efficacy of testing in donor screening. 
HIV-Antigen Study Group. NEJM 323:1312-7; 1990.
 2. Busch MP, PE Taylor, BA Lenes, et al.  Screening of selected
male blood donors for p24 antigen of human immunodeficiency
type 1.  Transfusion Safety Study Group. NEJM 323:1308-12;
1990.
 3. Gilcher RO, J Smith, S Thompson, et al.  Transfusion-associated
HIV from anti-HIV non-reactive, HIV antigen reactive donor
blood (Abstract #S-237).  ISBT-AABB Joint Congress, Los
Angeles, CA, Nov 1990.
 4. Irani MS, AW Dudley Jr, LJ Lucco.  Case of HIV-1 transmission
by antigen-positive, antibody negative blood (letter).  NEJM
325:1174-5; 1991.
 5. Roberts CS, JN Longfield, RC Platte, et al.  Transfusion-
associated human immunodeficiency virus type 1 from screened
antibody-negative blood donors.  Arch Pathol Lab Med 118:1188-
92; 1994.
 6. Lackritz EM, GA Satten, CP Raimondi, et al.  Estimated risk of
HIV transmission by screened blood in the U.S.  Abstracts, 2nd
International Conference on Human Retroviruses and Related
Infections, Washington, DC.  January, 1995.  [Updated at the
48th Meeting of the Blood Products Advisory Committee,
Bethesda, MD, June 23, 1995.]
 
 7. Ward JW, SD Holmberg, JR Allen, et al.  Transmission of human
immunodeficiency virus (HIV) by blood transfusions screened as
negative for HIV antibody.  NEJM 318:473-8; 1988.
 8. Cumming PD, EL  Wallace, JB Schorr, RY Dodd.  Exposure of
patients to human immunodeficiency virus through the
transfusion of blood components that test antibody-negative. 
NEJM 321:941-6; 1989.
 9. Busch MP, LLL Lee, GA Satten, et al.  Time Course of detection
of viral and serologic markers preceding human immunodeficiency
virus type 1 seroconversion: implications for screening of
blood and tissues donors.  Transfusion 35(2):91-7;  1995.
10. Busch MP and HJ Alter.  Will human immunodeficiency virus p24
antigen screening increase the safety of the blood supply and,
if so, at what cost?  Transfusion 35(7):536-9; 1995.
13 Figure 1  
FDA RECOMMENDATIONS FOR DONOR DEFERRAL AND MANAGEMENT OF UNITS
BASED ON SCREENING TESTS FOR HIV-1 ANTIGEN(S)
Repeatedly Reactive HIV-1 Antigen
  Screening Test Result
    99
    99
Quarantine unit; destroy or label appropriately
Defer donor for a minimum of 8 weeks
Retrieve and quarantine prior collections dating back 3 months
(Refer to Figure 2 for disposition of prior collections)
    99
         99
Perform Neutralization Test
------------------------------------------------------------------------------------------
Neutralized Invalid Not Neutralized
Interpret sample as Interpret sample as Interpret sample as
POSITIVE for HIV-1 Ag  77 77 77 INDETERMINATE   66 66  INDETERMINATE 
 99        88     99 88 (low probability of
 99        88     99 88  HIV)
 99        88     99 88   99
 99        88     99 88   99
Defer donor permanently.   88          Retest original or 88   99
Provide appropriate           77 77 77   fresh specimen.66 66 66   99
counseling.  Notify     99         99
consignees.  Retest     99      99
donor for HIV antibodies     99      99
after 8 weeks.     99     99
   Retest invalid (or not performed)   99
    99     99
        99 77 77 77 77 77 77 77 77 77 77 77 77 77 77 77 77
    99
   Provide appropriate counseling
  Notify consignees
Retest donor after 8 weeks (donor is eligible for reentry)
14 Figure 2  
FDA RECOMMENDATIONS FOR DONOR REENTRY AND FOR 
DISPOSITION OF QUARANTINED UNITS FROM PRIOR (NEGATIVE) COLLECTIONS
FOLLOWING A REPEATEDLY REACTIVE SCREENING TEST
FOR HIV-1 ANTIGEN(S)
Donor is eligible for reentry based on a
NEGATIVE or INDETERMINATE test for HIV-1 antigen(s) including Neutralization Testing
Obtain follow-up specimen >8 weeks after repeatedly reactive test
Perform screening tests for HIV-1 Antigen(s) and 
for antibodies to HIV-1 and HIV-21
                  ----------------------------------------------------------------------
Repeatedly Reactive on  Negative
any screening test for all markers 
99 99
99 99
99 99
99     99
Defer donor permanently.  Reenter donor.
Destroy or suitably label current unit Current unit may be used
and units from prior (negative) if donor is otherwise
collections. suitable.  Quarantined units
from prior (negative)
collections may be released. 
     1If retesting of the donor is not performed within six months, any quarantined
units  from prior collections should be destroyed or suitably relabeled.
15