Measles vaccination during the respiratory virus season and risk of vaccine failure.

OBJECTIVE: To determine whether measles vaccine failure is more common in persons who were vaccinated during the respiratory virus season, when they were more likely to have had concurrent minor illnesses. DESIGN: Population-based case series and case-control study. SETTING: Wisconsin and Ohio. SUBJECTS: The case series included all 545 of the states' residents who had confirmed measles reported during 1985 through 1990 and a history of receiving a single dose of measles vaccine during 1975 through 1988 at 15 to 59 months of age. In a case-control study restricted to 1984 through 1988 vaccinees, season of vaccination was compared in 170 case children and 6070 control students. MAIN OUTCOME MEASURE: Risk of clinical vaccine failure after measles vaccination during the respiratory virus season (September through May) or the peak season (November through March) compared with summertime (June through August), after adjustment for age at vaccination and place of residence. RESULTS: In the case series of persons with vaccine failure, the proportion who had been vaccinated during the respiratory virus season (74.7%) was no greater than expected (September through May = 74.8% of the year). In the case-control study, vaccination during the respiratory virus season (odds ratio, 0.92; 95% confidence interval, 0.66 to 1.30) or the peak season (odds ratio, 0.93) did not increase the risk of vaccine failure. CONCLUSION: Despite the high and strongly seasonal prevalence of viral respiratory illness in young children, routine childhood measles vaccination during the respiratory virus season does not increase their risk of vaccine failure. Findings provide epidemiologic support for recently strengthened recommendations that measles vaccination not be deferred in children with minor respiratory illnesses.

Household-acquisition of measles and illness severity in an urban community in the United States.

Studies from developing countries suggest that persons with household-acquired (HA) measles are at greater risk of severe illness than persons with community-acquired (CA) infection. Reported measles cases occurring among Milwaukee residents from May 1989 to June 1990 were used to assess whether household-acquisition was a risk factor for severe measles in the United States. A case was classified as HA if onset of rash occurred 7-18 days after onset of rash in another case in the same household. Hospitalization rates were similar for 128 patients with HA measles (27%) and for 1004 patients with CA measles (26%). Multiple logistic regression was used to evaluate the association between hospitalization and household-acquisition after controlling for socioeconomic status, measles vaccination history, age, race, and date of onset of rash. Patients with HA measles were no more likely to be hospitalized than patients with CA measles (odds ratio 0.9, 95% confidence interval 0.6, 1.5). HA measles cases were not more severe than CA measles cases during this urban outbreak in the United States.

Swine influenza virus infections. Transmission from ill pigs to humans at a Wisconsin agricultural fair and subsequent probable person-to-person transmission.

In September 1988, a previously healthy 32-year-old pregnant woman was hospitalized for pneumonia and died 8 days later. The only pathogen detected was an influenza virus antigenically related to the swine influenza virus (SIV). Four days before illness onset, the patient visited a county fair swine exhibition where there was widespread influenzalike illness among the swine. To detect other persons who were possibly infected by contact with the ill swine, we measured serum SIV hemagglutination-inhibition antibody titer in 25 swine exhibitors who were 9 to 19 years old. Nineteen (76%) had SIV hemagglutination-inhibition titers of 20 or greater. Antibody was undetectable in serum samples from 25 swine exhibitors from a neighboring county. Additional studies suggest that one to three health care personnel who had contact with the patient developed influenzalike illnesses with laboratory evidence of SIV infection. An outbreak of apparent SIV infection in swine resulted in multiple human infections, and, although no recognized community outbreak resulted, there was evidence of virus transmission from the patient to health care personnel.