Observed peaks of acute flaccid myelitis (AFM) cases have occurred biennially since 2014 in the United States. We aimed to determine if AFM etiology differed between peak and nonpeak years, considering that clinical features of AFM differ by virus etiology. We compared clinical and laboratory characteristics of AFM cases that occurred during peak (2016 and 2018, n = 366) and nonpeak (2015 and 2017, n = 50) years. AFM patients in peak years were younger (5.2 years) than those in nonpeak years (8.3 years). A higher percentage of patients in peak years than nonpeak years had pleocytosis (86% vs. 60%), upper extremity involvement (33% vs. 16%), and an illness preceding limb weakness (90% vs. 62%) and were positive for enterovirus or rhinovirus RNA (38% vs. 16%). Enterovirus D68 infection was associated with AFM only in peak years. Our findings suggest AFM etiology differs between peak and nonpeak years.

Risk factors for herpes zoster (HZ) are poorly defined. An age-matched case-control study was conducted to assess the effect of physical trauma on HZ using Medicare data. HZ cases were 3.4 times as likely as controls to have experienced trauma in the week before HZ onset, but the magnitude of the association between trauma and HZ declined over time. Cases who had cranial HZ were >25 times more likely than controls to have had cranial trauma in the week before HZ onset. Therefore, recent trauma can be a trigger for HZ.

BACKGROUND: Herpes zoster (HZ) vaccine was recommended in the United States to reduce HZ-associated morbidity. Vaccination may reduce HZ-associated mortality, but no strategy exists to monitor mortality trends. METHODS: We validated HZ coding on death certificates from California, using hospital records as the gold standard, and applied the results to national-level data to estimate HZ mortality. RESULTS: In the validation phase of the study, among 40 available hospital records listing HZ as the underlying cause of death, HZ was the underlying cause for 21 (52.5%) and a contributing cause for 5 (12.5%). Among 21 hospital records listing HZ as the underlying cause of death, the median age of decedents was 84 years (range 50-99); 60% had no contraindications for HZ vaccination. Of the 37 available records listing HZ as a contributing cause of death, HZ was a contributing cause for 2 (5.4%) and the underlying cause for 6 (16.2%). Nationally, in the 7 years preceding the HZ vaccination program, the average annual number of deaths in which HZ was reported as the underlying cause of death was 149; however, based on our validation study, we estimate the true number was 78 (range: 31-118). CONCLUSION: National death certificate data greatly overestimate deaths in which HZ is the underlying or contributing cause of death. The HZ vaccination program could prevent some HZ-related deaths but the impact will be difficult to assess using national mortality data.

OBJECTIVE: Varicella has been preventable by vaccination in the United States since 1995. Previous studies reported a 66% decline in mortality rate during the first 6 years of the program. Since then, vaccination coverage has increased substantially. We updated the analysis of US varicella mortality for 2002-2007 and assessed the impact of the first 12 years of the US varicella vaccination program on varicella deaths. METHODS: National data on deaths for which varicella was listed as an underlying or contributing cause were obtained from the Mortality Multiple Cause-of-Death records from the US National Center for Health Statistics. We calculated the age-adjusted and age-specific mortality rates for 2002-2007 and trends since the prevaccine years. RESULTS: During the 12 years of the mostly 1-dose US varicella vaccination program, the annual average mortality rate for varicella listed as the underlying cause declined 88%, from 0.41 per million population in 1990-1994 to 0.05 per million population in 2005-2007. The decline occurred in all age groups, and there was an extremely high reduction among children and adolescents younger than 20 years (97%) and among subjects younger than 50 years overall (96%). In the last 6 years analyzed (2002-2007), a total of 3 deaths per age range were reported among children aged 1 to 4 and 5 to 9 years, compared with an annual average of 13 and 16 deaths, respectively, during the prevaccine years. CONCLUSIONS: The impressive decline in varicella deaths can be directly attributed to successful implementation of the 1-dose vaccination program. With the current 2-dose program, there is potential that these most severe outcomes of a vaccine-preventable disease could be eliminated.