MMWR

Morbidity and Mortality Weekly Report

Interim Within-Season Estimate of the Effectiveness of Trivalent Inactivated Influenza Vaccine — Marshfield, Wisconsin, 2007–08 Influenza Season

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Laboratory data on antigenic characterization of circulating influenza viruses compared with vaccine strains should be interpreted together with data on the clinical effectiveness of vaccination in preventing laboratory-confirmed influenza illnesses. This report summarizes interim results of a 2008 study to estimate the effectiveness of trivalent inactivated influenza vaccine for prevention of medically attended, laboratory-confirmed influenza during the 2007–08 influenza season, when most circulating influenza A (H3N2) and B viruses were suboptimally matched to the vaccine strains. Despite the suboptimal match between two of three vaccine strains and circulating influenza strains, overall Vaccine Effectiveness (VE) in the study population was 44 percent (95 percent confidence interval [CI] 11 percent – 65 percent). The estimate of VE for prevention of medically attended influenza A infections was 58 percent. No VE was observed for prevention of medically attended influenza B infections. The findings indicate that in any season, assessment of the clinical effectiveness of influenza vaccines cannot be determined solely on the basis of laboratory evaluation of the degree of antigenic match between vaccine and circulation strains.

Rotavirus Vaccine Coverage and Adherence to Age Recommendations — United States, February 2006–May 2007

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Routine vaccination is anticipated to be the most effective public health intervention for reducing rotavirus disease in children. Health-care providers should remain vigilant in following the ACIP-recommended vaccination schedule for rotavirus vaccine. Worldwide, rotavirus is the leading cause of severe gastroenteritis in children less than 5 years old, and each year it results in more than 200,000 emergency room visits and 55,000-70,000 hospitalizations in the U.S. alone. In February 2006, a new rotavirus vaccine, RotaTeq® (Merck & Co., Inc. Whitehouse Station, NJ), was recommended by the Advisory Committee on Immunization Practices (ACIP) for routine vaccination of U.S. infants as a 3-doses schedule, to be administered at 2, 4, and 6 months of age. CDC assessed rotavirus vaccination coverage among U.S. infants during February 2006–May 2007 and examined adherence to the ACIP-recommended vaccination schedule. The findings of the analysis were that, by May 15, 2007, nearly half of 3-month-old infants had received 1 dose of rotavirus vaccine and that the majority of doses were administered according to ACIP recommendations.

Laboratory-Acquired Vaccinia Infections and Vaccinia Exposure — United States, 2005–2007

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Researchers who handle non-attenuated strains of vaccinia virus should follow ACIP recommendations for vaccination against vaccinia. Vaccinia virus (VACV) is used in research laboratories, and accidental inoculation in the laboratory can result in severe infection. The Advisory Committee on Immunization Practices (ACIP) recommends vaccination with the vaccinia (smallpox) vaccine at least every 10 years for researchers who have contact with non-attenuated strains of VACV. In this MMWR, 5 recent instances of laboratory-related VACV exposure, including 4 infections, and 2 hospitalizations are described. In all instances, the researchers recovered, but had not met ACIP recommendations for vaccination. These observations underscore the need for laboratory researchers and occupational health clinics to review vaccination status of researchers who handle non-attenuated VACV strains, as well as reinforce laboratory safety practices.

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES