Synopsis for August 13, 2004

The MMWR is embargoed until Thursday, 12 PM EDT.

1. Assessment of the Effectiveness of the 2003-04 Influenza Vaccine Among Children and Adults ― Colorado, 2003
2. Aseptic Meningitis Outbreak Associated With Echovirus 9 Among Recreational Vehicle Campers ― Connecticut, 2003
3. Epidemiology of Measles ― United States, 2001-2003
4. Congenital Syphilis ― United States, 2002
5. West Nile Virus Activity ― United States, August 4-August 10, 2004

Synopsis for August 13, 2004

Assessment of the Effectiveness of the 2003-04 Influenza Vaccine Among Children and Adults ― Colorado, 2003

The 2003-04 influenza vaccine provided substantial protection even though the vaccine match was not optimal.

Two studies were conducted in Colorado to estimate the effectiveness of the 2003-04 vaccine. A study among children 6-23 months of age found the vaccine was 25-49 percent effective in preventing influenza-like illness (ILI). Since the ILI outcome would include many respiratory illnesses NOT due to influenza but caused by other viruses and bacteria, and because the vaccine can ONLY prevent illness specifically caused by influenza viruses, these are very favorable estimates and showed that the influenza vaccine was quite effective in young children. A second study was done in adults 50-64 years of age. This study found that the vaccine was 52 percent effective among otherwise healthy adults and 38 percent effective against adults with one or more chronic medical conditions in preventing laboratory confirmed influenza. In otherwise healthy young adults, the vaccine is expected to 70-90 percent effective against laboratory confirmed influenza in years when the vaccine and circulating strains are well matched. In 2003-04, the predominant circulating strain was not optimally matched to the vaccine strain. However, despite this mismatch, these studies showed that the vaccine still provided substantial benefit to both children and adults. These study results contradict preliminary results of a study of ILI among healthcare workers, published by CDC that did not find effectiveness. Many of the limitations of the healthcare worker study are addressed in these two newly released studies.

Aseptic Meningitis Outbreak Associated With Echovirus 9 Among Recreational Vehicle Campers ―
Connecticut, 2003

Pool operators should check chlorine and pH levels frequently, particularly during peak pool occupancy, and adults should take precautions against passing enterovirus to children, who are at greater risk for severe illness.

Crowded conditions in the campground swimming pool and inside Recreational Vehicles (RVs) likely facilitated enterovirus spread, which contributed to this aseptic meningitis outbreak. Pool chlorine levels were low in the evening. The hot sun and high occupancy likely reduced chlorine levels during the day, allowing the pool water to become contaminated with enterovirus. Pool operators should check chlorine and pH levels frequently, particularly during peak pool occupancy, even if levels are appropriate when a pool is opened. This group’s high rate of illness was also facilitated by enterovirus spread among residents of the same campsite promoted by crowding. To minimize viral spread to children in their care, ill caregivers should wash their hands thoroughly after toilet use and avoid sharing drinks and utensils, because children are at greater risk for severe illness.

Epidemiology of Measles ― United States, 2001-2003

Maintaining immunity through high vaccination coverage levels is essential in limiting the spread of measles from imported cases and preventing measles from becoming endemic in the United States.

Measles is a highly infectious, acute viral illness that can cause severe pneumonia, diarrhea, and encephalitis, and death. To characterize the epidemiology of measles in the United States during 2001–2003, CDC analyzed data reported by state and local health departments. The low number of reported measles cases and the limited indigenous transmission from imported cases demonstrates that no endemic measles virus is circulating in the United States as a result of high levels of immunity in the population. Population immunity is due to high levels of vaccine coverage. However, imported measles cases continue to occur and indigenous transmission would be higher if high vaccination coverage levels are not maintained.

Congenital Syphilis ― United States, 2002

Cases of congenital syphilis (CS), which occur when an infected pregnant woman passes syphilis to her fetus, declined in 2002, continuing a downward trend that began in 1991.

CS can cause stillbirth, death soon after birth or neurological problems in those children who survive. In 2002, 451 cases of CS were reported, down from 578 cases in 2000, the last year for which CS data were reported. Rates decreased more than 20 percent, from 14.2 cases per 100,000 live births in 2000 to 11.2 cases in 2002, reflecting a decline of more than 30 percent in the rate of primary and secondary syphilis among women during these years. CS rates decreased among all racial and ethnic minority groups and across all regions of the United States except the Northeast. Nearly 75 percent of all reported cases occurred because mothers received inadequate treatment or no treatment for syphilis before or during pregnancy. In nearly one-third of cases, the mother received no prenatal care. Authors note that programs designed to increase access to prenatal care for underinsured and uninsured women can help further reduce CS. Improved provider adherence to syphilis screening and treatment guidelines can also help drive cases down.

West Nile Virus Activity ― United States,
August 4-August 10, 2004

No summary available.

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