Inactivated influenza vaccine (IIV) in children <2 years of age: examination of selected adverse events reported to the Vaccine Adverse Event Reporting System (VAERS) after thimerosal-free or thimerosal-containing vaccine.

Thimerosal as a preservative (in all but trace amounts) was removed from vaccines used in infants starting in the late 1990s, though the preservative-including inactivated influenza vaccine is still available for use in individuals >or=6 months of age. We compared the proportion of injection site reactions, rash, and infections reported to the Vaccine Adverse Event Reporting System (VAERS) after preservative-free (PFV), preservative-including (PIV), and preservative unknown (PUV) vaccines in reports from 7/1/2004 to 1/4/2006. There were 145, 175, and 216 reports after vaccination with PFV, PIV, and PUV, respectively. The most frequently reported coding terms (fever, rash, and urticaria) were seen in similar proportions in the PFV, PIV, and PUV groups. No difference was detected in the proportion of injection site reactions (ISR), rash, or infections in the PIV, PFV, and PUV reports. Keeping in mind the inherent limitations of VAERS, including underreporting and potential reporting biases, we conclude that there were no substantial differences in the proportion of rash, ISR, and infection reports in the PIV, PFV and PUV reports in infants.

Norwalk virus-associated gastroenteritis traced to ice consumption aboard a cruise ship in Hawaii: comparison and application of molecular method-based assays.

Investigation of an outbreak of acute nonbacterial gastroenteritis on a cruise ship provided an opportunity to assess new molecular method-based diagnostic methods for Norwalk virus (NV) and the antibody response to NV infection. The outbreak began within 36 h of embarkation and affected 30% of 672 passengers and crew. No single meal, seating, or food item was implicated in the transmission of NV, but a passenger's risk of illness was associated with the amount of ice (but not water) consumed (chi-square for trend, P = 0.009). Of 19 fecal specimens examined, 7 were found to contain 27-nm NV-like particles by electron microscopy and 16 were positive by PCR with very sensitive NV-specific primers, but only 5 were positive by a new highly specific antigen enzyme immunoassay for NV. Ten of 12 serum specimen pairs demonstrated a fourfold or greater rise in antibody titer to recombinant baculovirus-expressed NV antigen. The amplified PCR band shared only 81% nucleotide sequence homology with the reference NV strain, which may explain the lack of utility of the fecal specimen enzyme immunoassay. This report, the first to document the use of these molecular method-based assays for investigation of an outbreak, demonstrates the importance of highly sensitive viral diagnostics such as PCR and serodiagnosis for the epidemiologic investigation of NV gastroenteritis.