# Presentation: 698802

## West Nile Virus

- Maria Rios, Ph.D.
- Pradip Akolkar, Ph.D.
- CBER/FDA
- Blood Product Advisory Committee
- July 13, 2006

- Update

##  WNV Human Infection

- *All seronegative for WNV; + Lack of f/up, sample, recipient loss
- ‡ Negative in MP-NAT and positive on ID-NAT (low viremia)

| WNV in humans | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Disease (n~20, 000) | 62 | 21 | 66 | 4,156 | 9,862 | 2,539 | 3,000 |
| Fatal cases (n=785) | 7 | 2 | 9 | 284 | 264 | 100 | 119 |

| Neuroinvasive cases (n=8,386) | 59 | 19 | 64 | 2,942 | 2,866 | 1,142 | 1,294 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Estimated # infections (~1,300,000)  | 8,850 | 2,850 | 9,600 | 441,300 | 429,900 | 173,000 | 194,100 |

**Transmission by Transfusion **

| PVD (n > 1,600) |   |   |   | ~1000 | >1,000 | 221 | 399 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| TT confirmed* (n=30) |   |   |   | 23 | 6 ‡ | 1 ‡ |  0 |
| TT inconclusive+ (n=26) |   |   |   | 19 | 6 | 1 | 0 |

## Onset of Human WNV Disease,

- United States 1999-2005*

***Reported as of 2/14/2006**

***Reported as of 2/14/2006**

**Notes:**
The human WNV season was quite short in 1999; however, it steadily lengthened over the following years, and reached the longest duration yet in 2005, spanning almost the entire year, from Jan. 2 to Dec. 16.

## History of WNV and Blood safety

**2002**
- Identification of risk for WNV in the blood safety
- Initiative of OBRR/CBER call for test development
- Collaboration between Government, Academia, Industry and Blood establishments
**2003**
- Development and nationwide implementation of blood screening for WNV by MP-NAT (6 or 16 donations) under FDA approved INDs
- Interdiction of WNV reactive donations made by asymptomatic donors
- Evaluation of MP-NAT sensitivity by retrospective studies
**2004 and 2005**
- ID-NAT replaced MP-NAT in specific areas of high WNV activity during limited periods of time

## Status of WNV Assays

- FDA licensed the first WNV NAT for volunteer blood donor screening (Procleix® WNV Assay on eSAS) in December 2005
- Other WNV NAT for donor screening are currently under IND

## Current Considerations:

-  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 the implementation of 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 Considerations: Testing

- WNV became endemic in the US with intense activity re-occurring between spring and fall
- The screening of volunteer donors of Whole Blood and blood components for transfusion for WNV RNA will improve the safety of the nation’s blood supply
- WNV screening by MP-NAT should be performed year-round, with implementation of ID-NAT in specific geographical areas where WNV activity is high
- Criteria to trigger ID-NAT in a given geographical area, and to revert back to MP-NAT, should be defined and validated by the centers, based on incidence rates

## Current Considerations: Testing

- We are considering recommending confirmation of initial reactivity in the index donation by retesting that donation
- 	a. using the same assay in duplicate
- 	b. using alternate NAT with sensitivity comparable to 	that of the screening assay
- Encourage the use of antibody testing on the initial donation

## Current considerations:

- Donor Management

- WNV is a communicable agent to the CDC
- Reasonable attempts to be made to notify deferred donors of test results
- We encourage additional testing to be performed as follows:
- a.	Alternate NAT and antibody testing in the index donation may provide information for donor counseling purposes
- b.	Follow-up testing may provide further information on the course and outcome of infection, and antibody testing may work as a confirmatory tool

## Considerations on Labeling

- 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

##  		Current Considerations for:
			Donor Deferral and Reentry
			Unit Management
			Recipient Notification
	Are to remain as stated in the June 2005 Guidance: WWW.fda.gov/cber/gdlns/wnvguid.htm

- 			Donor Deferral and Reentry
- 			Unit Management
- 			Recipient Notification
- 	Are to remain as stated in the June 2005 Guidance: WWW.fda.gov/cber/gdlns/wnvguid.htm