An Analysis of SARS-CoV-2 Vaccine Breakthrough Infections and Associated Clinical Outcomes

Understanding the rate and clinical features associated with vaccine breakthrough infections (VBT) is of critical public health importance. Recent evidence on VBT in Barnstable County, Massachusetts, has prompted guidance on masking for vaccinated individuals in areas of high community-level transmission. Additional data is needed to better understand the prevalence and rate of VBT infections. Using detailed disease investigation data from Washoe County, Nevada we sought to assess the rate of symptomatic infection and serious illness among VBT cases compared to non-vaccinated individuals with COVID-19. From February 12 - July 29, 2021, the Washoe County Health District identified and traced 6,128 out of 6,399 reported cases across the sample period. 338 (5.5%) of all cases were identified as breakthrough infections, and 289 (86%) vaccinated individuals had symptomatic infections. Severe clinical outcomes were infrequent with 17 hospitalizations (5% of VBT) and no deaths. Cycle threshold values were not statistically different between vaccinated and unvaccinated individuals.

Particulate matter and emergency visits for asthma: a time-series study of their association in the presence and absence of wildfire smoke in Reno, Nevada, 2013-2018

Background: Health risks due to particulate matter (PM) from wildfires may differ from risk due to PM from other sources. In places frequently subjected to wildfire smoke, such as Reno, Nevada, it is critical to determine whether wildfire PM poses unique risks. Our goal was to quantify the difference in the association of adverse asthma events with PM on days when wildfire smoke was present versus days when wildfire smoke was not present. Methods: We obtained counts of visits for asthma at emergency departments and urgent care centers from a large regional healthcare system in Reno for the years 2013-2018. We also obtained dates when wildfire smoke was present from the Washoe County Health District Air Quality Management Division. We then examined whether the presence of wildfire smoke modified the association of PM 2.5 , PM 10-2.5 , and PM 10 with asthma visits using generalized additive models. We improved on previous studies by accounting for possible non-linearity in the association between PM concentration and asthma visits: wildfire-smoke days where the PM concentration exceeded the maximum PM concentration on other days were excluded. Results: Air quality was affected by wildfire smoke on 188 days between 2013 and 2018. We found that the presence of wildfire smoke increased the association of a 5 µg/m 3 increase in daily and three-day averages of PM 2.5 with asthma visits by 6.1% (95% confidence interval (CI): 2.1-10.3%) and 6.8% (CI: 1.2-12.7%), respectively. Similarly, the presence of wildfire smoke increased the association of a 5 µg/m 3 increase in daily and three-day averages of PM 10 with asthma visits by 5.5% (CI: 2.5-8.6%) and 7.2% (CI: 2.6-12.0%), respectively. We did not observe any significant increases in association for PM 10-2.5 or for seven-day averages of PM 2.5­ and PM 10 . Conclusions: Since we found significantly stronger associations of PM 2.5 and PM 10 with asthma visits when wildfire smoke was present, our results suggest that wildfire PM is more hazardous than non-wildfire PM for patients with asthma.

Particulate matter and emergency visits for asthma: a time-series study of their association in the presence and absence of wildfire smoke in Reno, Nevada, 2013-2018

Background: Health risks due to particulate matter (PM) from wildfires may differ from risk due to PM from other sources. In places frequently subjected to wildfire smoke, such as Reno, Nevada, it is critical to determine whether wildfire PM poses unique risks. Our goal was to quantify the difference in the association of adverse asthma events with PM on days when wildfire smoke was present versus days when wildfire smoke was not present. Methods: We obtained counts of visits for asthma at emergency departments and urgent care centers from a large regional healthcare system in Reno for the years 2013-2018. We also obtained dates when wildfire smoke was present from the Washoe County Health District Air Quality Management Division. We then examined whether the presence of wildfire smoke modified the association of PM 2.5 , PM 10-2.5 , and PM 10 with asthma visits using generalized additive models. We improved on previous studies by accounting for possible non-linearity in the association between PM concentration and asthma visits: wildfire-smoke days where the PM concentration exceeded the maximum PM concentration on other days were excluded. Results: Air quality was affected by wildfire smoke on 188 days between 2013 and 2018. We found that the presence of wildfire smoke increased the association of a 5 µg/m 3 increase in daily and three-day averages of PM 2.5 with asthma visits by 6.1% (95% confidence interval (CI): 2.1-10.3%) and 6.8% (CI: 1.2-12.7%), respectively. Similarly, the presence of wildfire smoke increased the association of a 5 µg/m 3 increase in daily and three-day averages of PM 10 with asthma visits by 5.5% (CI: 2.5-8.6%) and 7.2% (CI: 2.6-12.0%), respectively. We did not observe any significant increases in association for PM 10-2.5 or for seven-day averages of PM 2.5­ and PM 10 . Conclusions: Since we found significantly stronger associations of PM 2.5 and PM 10 with asthma visits when wildfire smoke was present, our results suggest that wildfire PM is more hazardous than non-wildfire PM for patients with asthma.