# Presentation: 773485

## Current Considerations for Blood Donor Screening for West Nile Virus

**Current Considerations for ****Blood Donor Screening for ****West Nile Virus**

**Pradip N. Akolkar, Ph.D.**
**Maria Rios, Ph.D.**
**DETTD, OBRR**
**Blood Products Advisory Committee March 9, 2006**

## Background 

_***Summer 1999***_**:  First outbreak of WNV in the US**
_***August 2002***_**:  The theoretical potential for transmission of WNV by blood transfusion was raised in a publication by CDC *****(Transfusion. August 2002, 42:1019)***
_***September 2002***_**:  Transmission of WNV by transplantation was confirmed, followed by the confirmation of transmission by transfusion *****(MMWR 2002; 51(35):790)***
***	*****AABB sponsored meeting of decision makers, experts in the field from various Govt. agencies, blood and device industry**

## Background..... 

**Background..... **

_***November 2002***_**:**  **FDA sponsored workshop aiming to support test development and facilitate communication between test manufacturers and users**
_***July 2003***_**:  Nationwide screening of volunteer blood donations for WNV RNA using NAT implemented under approved INDs performed on mini-pools (MP-NAT) of 6 or 16 donations, depending on the assay**

## Background..... 

_***November 2003***_**:  Evaluation of MP-NAT sensitivity to detect low viremia by retrospective studies using ID-NAT**
**Identification of ID-NAT-positive and MP-NAT-negative units **
** ****6 confirmed cases of WNV transmission by transfusion of MP-NAT-negative units**
_***Summer 2004 and 2005***_**:  Prospective testing by ID-NAT replaced MP-NAT in areas of high WNV activity during limited periods of time**

## Benefits of WNV Screening

_**Year**_**	****	**_**Units Interdicted**_**	**_**No. T.T. Cases**_
**2002****	****	****	****  -****	****	****	****	****23**
**2003****	****	****	****818****	****	****	****	****  6**
**2004****	****	****	****198****	****	****	****	****  1**
**2005****	****	****	****398****	****	****	****	****  0**

**Source: CDC update to AABB WNV Taskforce**

## Status of WNV Assays

**FDA licensed first WNV NAT for volunteer blood donor screening (Procleix® WNV Assay on eSAS) in December 2005**
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## Current Considerations on Assay Implementation

- 	**We recognize that WNV RNA NAT for testing samples from volunteer blood donations for transfusion may involve the use of complex pooling and testing systems**
**	****We are considering recommending that you implement a licensed NAT for WNV RNA within six months from the date of the publication of a Notice in the Federal Register announcing the availability of the **_**Final guidance**_

## Current Testing Considerations

**The implementation of licensed NAT for WNV RNA for screening volunteer donors of Whole Blood and blood components for transfusion will improve the safety of the nation’s blood supply**
**WNV screening by MP-NAT to be performed year-round with implementation of ID-NAT in specific geographical areas where WNV activity is high**

## Current Testing 

**Considerations (Cont.)**

**Switch from MP- to ID-NAT to**** ****be defined by triggers based on incidence rates. This would increase the sensitivity of WNV testing within the constraints of available technology and personnel**
**We need a dialogue with the blood establishments regarding the criteria to define the trigger to switch from MP-NAT to ID-NAT in geographical areas with high WNV activity, and the appropriate parameter to switch back from ID-NAT to MP-NAT**** **

## Donor Deferral and Reentry Considerations

**Diagnosed or suspected acute WNV illness or infection:**
**Defer donor for 120 days following diagnosis or onset of illness**
**Presumptive viremia (WNV NAT-reactive):**
**Defer donor for 120 days following date of NAT-reactive donation**

**(June 2005 Guidance **_[www.fda.gov/cber/gdlns/wnvguid.htm](http://www.fda.gov/cber/gdlns/wnvguid.htm)__)_

## Donor Deferral and Reentry Considerations (Cont.)

**Suspected WNV illness in a donor within 2 weeks after donation:**
**Defer donor for 120 days following onset of illness**
**Donor who may have transmitted WNV infection:**
**Defer donor for 120 days following date of donation**
** ****May reenter deferred donor after 120 days**

**(June 2005, **_[www.fda.gov/cber/gdlns/wnvguid.htm](http://www.fda.gov/cber/gdlns/wnvguid.htm)__)_

## Donor Management Considerations

**Reasonable attempts be made to notify deferred donors of test results**
**Additional testing **
**Alternate NAT and antibody testing may provide information for donor counseling purposes**
**Follow-up testing may provide further information on the course and outcome of infection**

## Unit Management Considerations

**Discard units that are NAT-reactive**
**Retrieve and quarantine in-date blood and blood components including unpooled recovered plasma, Source Plasma and Source Leukocytes from a donor who:**
**-  Was diagnosed with WNV infection or illness**
**-  Is presumptively viremic (WNV NAT-reactive)**
**-  May have transmitted WNV infection**
**-  Has an undiagnosed illness that represents likely infection with WNV**

**(June 2005, **_[www.fda.gov/cber/gdlns/wnvguid.htm](http://www.fda.gov/cber/gdlns/wnvguid.htm)__)_

## Recipient Notification Considerations

**Blood establishments that receive information regarding diagnosis of WNV infection or illness may consider**** ****tracing records and notifying transfusion services regarding “relevant units”**
**Transfusion services may then consider notifying treating physicians of prior recipients**

**(June 2005, **_[www.fda.gov/cber/gdlns/wnvguid.htm](http://www.fda.gov/cber/gdlns/wnvguid.htm)__)_

## Labeling Considerations

**We are considering recommending:**
**The container label and instruction circular that reflects the results of WNV NAT be consistent with the labeling for other infectious disease markers upon implementation of licensed NAT**
**WNV reactive unit not be shipped or used except as provided in FDA approved programs and/or research or autologous use only and such units be labeled with appropriate warnings**