Methods: We retrospectively reviewed the charts of consecutive patients who underwent one- or two-level ACDF using polyetheretherketone cages by multiple surgeons from January 2015 to June 2016. We excluded patients younger than 18 years old, patients who had prior surgery at the same level (s), those with two-stage procedures, and those with less than 3 months of followup. Fusion was determined using the “Song” criteria. Ordinal regression was used to determine predictors of fusion. Patient-reported outcomes (PRO) were analyzed. Results: We identified 323 consecutive patients. Twenty-two patients met the exclusion criteria. A total of 435 operative levels were included in the 301 remaining patients. Interspace fusion did not significantly vary by increasing interspace height with fusion rates between 76.2% and 82.8% at a mean follow-up of 17.9±12.6 months. The effect of an increase in interspace height and neck pain PRO was available for 163 patients who underwent one-level ACDF at a mean follow-up period of 16.2±13.1 months. We found no significant difference in fusion rate or neck pain score with increasing interspace height from 1 to 8 mm. Ordinal regression demonstrated no significant predictors of fusion. Conclusions Interspace distraction from 1 to 8 mm did not result in significantly different pseudarthrosis rates or postoperative neck pain.

Nonpharmaceutical interventions (NPIs) have been commonly deployed to prevent and control the spread of the coronavirus disease 2019 (COVID-19), resulting in a worldwide decline in influenza prevalence. However, the influenza risk in China warrants cautious assessment. We conducted a cross-sectional, seroepidemiological study in Shandong Province, Northern China in mid-2021. Hemagglutination inhibition was performed to test antibodies against four influenza vaccine strains. A combination of descriptive and meta-analyses was adopted to compare the seroprevalence of influenza antibodies before and during the COVID-19 pandemic. The overall seroprevalence values against A/H1N1pdm09, A/H3N2, B/Victoria, and B/Yamagata were 17.8% (95% CI 16.2%-19.5%), 23.5% (95% CI 21.7%-25.4%), 7.6% (95% CI 6.6%-8.7%), and 15.0 (95% CI 13.5%-16.5%), respectively, in the study period. The overall vaccination rate was extremely low (2.6%). Our results revealed that antibody titers in vaccinated participants were significantly higher than those in unvaccinated individuals (P < 0.001). Notably, the meta-analysis showed that antibodies against A/H1N1pdm09 and A/H3N2 were significantly low in adults after the COVID-19 pandemic (P < 0.01). Increasing vaccination rates and maintaining NPIs are recommended to prevent an elevated influenza risk in China.