Guillermo A. Herrera

Estimated risk of HIV transmission by blood transfusion in Kenya

BACKGROUND During the past decade, developing countries have received limited support for blood safety programmes. The Kenya Ministry of Health did a collaborative multicentre assessment to establish the risk of HIV transmission by transfusion in Kenya, to promote awareness of blood safety issues in this country with a mature HIV epidemic, and to identify methods to reduce the risk of HIV transmission by blood transfusion in Kenya. METHODS For 12 weeks, from April to July 1994, we collected information and blood samples from all blood donors, and pretransfusion samples were collected from all recipients in six government hospitals in Kenya. Blood donations were collected and screened for HIV according to standard practice in the hospital laboratories. Test results at a reference laboratory were compared with those of the hospital laboratories and risk of transfusion-associated HIV transmission was calculated. FINDINGS The prevalence of HIV among blood donors was 6.4% (120 of 1877) and varied by hospital (range 2-20%). HIV test results were available for 1290 donor-recipient pairs. Of these, 26 HIV-positive donations were given to HIV-negative patients. We estimate that 2.0% of transfusions transmitted HIV. Problems in the hospitals that contributed to transfusion risk included inconsistent refrigeration, data entry errors, equipment failure, and lack of a quality-assurance programme. INTERPRETATION A high proportion of blood transfusions transmitted HIV in this high-prevalence area of Africa, primarily because of erroneous laboratory practices. On the basis of these results, the Kenya Ministry of Health introduced a number of practical and inexpensive interventions to improve national blood safety.

The effectiveness of the confidential unit exclusion option

BACKGROUND: The confidential unit exclusion (CUE) option is intended to reduce human immunodeficiency virus (HIV) transmission by excluding donors newly infected with HIV who have not yet developed HIV antibody (window‐period donors); however, its efficacy in excluding window‐ period donors has not been evaluated. STUDY DESIGN AND METHODS: The use of the CUE option was studied among the donors of 3.7 million units at 18 American Red Cross blood services regions during 1991 and 1992 and among 322 previously HIV‐1‐seronegative donors who subsequently donated a seropositive unit between 1987 and 1990 at 40 United States blood centers. These seroconverting donors had previously been shown to be highly likely to donate during their window period. RESULTS: On the basis of data from these two populations, it was estimated that only 3 to 5 percent of units donated by window‐period donors were not transfused because of the CUE option, that 0.4 percent of all donations were from donors who confidentially excluded their blood from transfusion, and that donors who confidentially excluded their blood were 21 times more likely to be HIV antibody‐positive than donors who did not use the CUE option. It is estimated that, if all US blood centers used the CUE option, a total of 2 to 17 otherwise acceptable units donated by window‐period donors would not be transfused annually. CONCLUSION: Although donors who confidentially exclude their blood from transfusion are 21 times more likely to have HIV antibody, the rarity of window‐period donors and the infrequency of confidential exclusion by window‐period donors cause the CUE option to have minimal impact on transfusion safety

Undervaccinated African-American preschoolers: A case of missed opportunities

OBJECTIVE To identify factors associated with undervaccination of African-American preschoolers, to describe the number of vaccination visits made by undervaccinated children and the number of visits needed to be series complete, and to describe the children who did not receive the single dose of measles-containing vaccine recommended for preschoolers. METHODS We used the 1999 National Immunization Survey (NIS) to describe vaccination coverage for the 4:3:1:3 vaccine series (four doses of diphtheria and tetanus toxoids and pertussis vaccine, three doses of poliovirus vaccine, one dose of any measles-containing vaccine, and three doses of Haemophilus influenzae type b vaccine) among non-Hispanic, African-American preschoolers due to concerns that they may be at risk of undervaccination. Children who did not complete this basic vaccine series were classified for further analysis according to the number of doses they lacked (i.e., one dose missed, two or three doses missed, or four or more doses missed). Significant associations between demographic characteristics and vaccination status or degree of undervaccination were determined. RESULTS Of the 26.2% of African-American preschoolers who did not complete the 4:3:1:3 vaccine series, 40.3% lacked one, 35.3% lacked two or three, and 25.0% lacked four or more doses of vaccine. Children who did not complete the 4:3:1:3 vaccine series were less likely to have married mothers, were less likely to have mothers aged > or = 35 years, or were less likely to be up to date at age 3 months than the children who completed the 4:3:1:3 vaccine series. Among the undervaccinated, 63.7% had a sufficient number of vaccination visits to have completed the basic series. However, most (78.7%) of the severely undervaccinated (children who lacked more than three doses of vaccine) had three or fewer vaccination visits. For 72.6% of the undervaccinated preschoolers, only one additional vaccination visit was needed to complete the 4:3:1:3 vaccine series; among these, 78.3% had an adequate number of vaccination visits to have completed the series. Overall, 9.9% of the African-American children aged 19 to 35 months (i.e., approximately 85,000 African-American children aged 19 to 35 months) were at risk for measles. Among the children who lacked more than three doses of vaccine, 68.1% were at risk. CONCLUSIONS Our study suggests that the estimated coverage of 73.8% for the 4:3:1:3 vaccine series among African-American children aged 19 to 35 months was not a result of limited access to care. On the contrary, 90.5% of African-American children had enough vaccination visits to complete the series. To raise coverage and prevent potential outbreaks, providers should assess each childs vaccination status at every visit, and administer all needed vaccinations at that time. For the most severely undervaccinated children, this strategy may not be adequate, because they did not have the minimum number of vaccination visits required for series completion. For these children, other strategies are needed for increasing vaccination coverage.

Serologic test for syphilis as a surrogate marker for human immunodeficiency virus infection among United States blood donors

BACKGROUND: This study evaluated the usefulness of the serologic test for syphilis (STS) in preventing the transmission of human immunodeficiency virus (HIV), hepatitis B and C viruses, and human T‐ lymphotropic virus via the transfusion of seronegative, infectious window‐period blood. STUDY DESIGN AND METHODS: Demographic and laboratory information on blood donations made between January 1992 and June 1994 in 18 American Red Cross regions was analyzed. It was assumed that the same proportion of HIV‐positive and HIV‐infectious window‐ period donations reacted on STS and were negative on other screening tests (hepatitis B and C viruses and human T‐lymphotropic virus). This proportion multiplied by the estimated number of HIV‐infectious window‐ period donations is the number of post‐screening HIV‐infectious donations removed by STS. RESULTS: Of 4,468,570 donations, 12,145 (0.27%) were STS positive and 377 (0.008%) were HIV positive. Among donations that were negative on other screening tests, STS‐reactive donations were 12 times more likely to be HIV positive (odds ratio=11.9; 95% CI=5,26). However, of an estimated 13 infectious window‐ period donations, 0.2 would have been removed because of a reactive STS, at a cost of over

Efectividad de la vacuna antigripal en individuos de 50-64 años de edad durante una estación de baja concordancia antigénica entre las cepas de virus de la vacuna y las cepas circulantes del virus de la gripe: Colorado, Estados Unidos, 2003-2004*

16 million. CONCLUSION: STS is a poor marker and a costly strategy for preventing post‐screening HIV infections and other blood‐borne diseases.

Neurological and Neuromuscular Disease as a Risk Factor for Respiratory Failure in Children Hospitalized With Influenza Infection

During the 2003-2004 influenza season, we conducted a case-control study of influenza vaccine effectiveness (VE) among Colorado residents aged 50-64 years. Cases (n = 330) were identified from laboratory-confirmed influenza reports to the Colorado Department of Public Health and Environment (CDPHE). Controls (n = 1,055) were recruited by random-digit dial telephone survey. VE was 60% (43-72%) and 48% (21-66%) among those without and with high-risk medical conditions, respectively. VE was 90% (68-97%) and 36% (0-63%) against influenza-related hospitalization for persons without and with high-risk conditions, respectively.