Trending prevalence of healthcare-associated infections in a tertiary hospital in China during the COVID-19 pandemic.

BACKGROUND: The purpose of this study was to demonstrate both the four-year prevalence trend of healthcare-associated infections (HAIs) in a large tertiary hospital and the trend regarding the prevalence of HAIs following the outbreak of coronavirus disease 2019 (COVID-19) in order to provide evidence of hospital infection management during the COVID-19 pandemic. METHODS: Based on the hospital's electronic nosocomial infection databases related to HAIs, we retrospectively identified the HAI cases to assess the epidemiological characteristics of HAIs from January 1, 2018, to December 31, 2021, in a large tertiary hospital in China. Similarly, the trends of HAIs after the COVID-19 outbreak and the seasonal variation of HAIs were further analyzed. RESULTS: The HAI cases (n = 7833) were identified from the inpatients (n = 483,258) during the 4 years. The most frequently occurring underlying cause of HAIs was respiratory tract infections (44.47%), followed by bloodstream infections (11.59%), and urinary tract infections (8.69%). The annual prevalence of HAIs decreased from 2.39% in 2018 to 1.41% in 2021 (P = 0.032), with the overall prevalence of HAIs significantly decreasing since the outbreak of COVID-19 (2.20% in 2018-2019 vs. 1.44% in 2020-2021, P < 0.001). The prevalence of respiratory tract infections decreased most significantly; whereas, overall, the prevalence of HAIs was significantly greater during the winter compared with the rest of the year. CONCLUSIONS: Not only did the annual prevalence of HAIs decrease from 2018 to 2021, but it also significantly decreased since the start of the COVID-19 pandemic, particularly respiratory tract infections. These results provide evidence for the need to prevent HAIs, especially during the winter season.

Effect of Inactivated SARS-CoV-2 Vaccine on Thyroid Function and Autoimmunity Within 28 Days After the Second Dose.

Background: The safety of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines is widely appreciated. However, there is limited knowledge regarding the potential impact of SARS-CoV-2 vaccines on the thyroid. Methods: We performed two prospective clinical trials between April and June, 2021, enrolling recipients of the inactivated SARS-CoV-2 vaccine (BBIBP-CorV and CoronaVac). Thyroid function, antithyroid antibody levels, and SARS-CoV-2 neutralizing antibody levels were detected for each participant before receiving the first vaccine dose and 28 days after receiving the second vaccine dose. Results: A total of 657 recipients participated in the study. The overall median thyroid function and levels of antithyroid antibodies before and after SARS-CoV-2 vaccination were within the normal range. Among the 564 participants with normal thyroid function at baseline, 36 (6.38% [confidence interval; CI 4.51-8.73]) developed thyroid dysfunction. Of the 545 recipients with negative antithyroid antibodies at baseline, none developed abnormal antibodies after vaccination. Notably, 75.27% (70/93 [CI 65.24-83.63]) of the 93 recipients with thyroid dysfunction returned to normal function after vaccination. The levels of antithyroid peroxidase antibody (96.20% [CI 89.30-99.21]) and antithyroglobulin antibody (TgAb; 88.31% [CI 78.97-94.51]) remained positive after vaccination in most patients with abnormal values at baseline. However, the TgAb levels in more than half of the patients (48/77) decreased. All of 11 abnormal thyrotropin receptor antibody levels at baseline decreased postvaccination. Conclusions: Vaccination with an inactivated SARS-CoV-2 vaccine had no significant adverse impact on thyroid function or antithyroid antibodies within the first 28 days after the second dose. Clinical Trial Registration: ChiCTR2100045109 and ChiCTR2100042222.

Robust induction of B cell and T cell responses by a third dose of inactivated SARS-CoV-2 vaccine.

SARS-CoV-2 inactivated vaccines have shown remarkable efficacy in clinical trials, especially in reducing severe illness and casualty. However, the waning of humoral immunity over time has raised concern over the durability of immune memory following vaccination. Thus, we conducted a nonrandomized trial among the healthcare workers (HCWs) to investigate the long-term sustainability of SARS-CoV-2-specific B cells and T cells stimulated by inactivated vaccines and the potential need for a third booster dose. Although neutralizing antibodies elicited by the standard two-dose vaccination schedule dropped from a peak of 29.3 arbitrary units (AU)/mL to 8.8 AU/mL 5 months after the second vaccination, spike-specific memory B and T cells were still detectable, forming the basis for a quick recall response. As expected, the faded humoral immune response was vigorously elevated to 63.6 AU/mL by 7.2 folds 1 week after the third dose along with abundant spike-specific circulating follicular helper T cells in parallel. Meanwhile, spike-specific CD4+ and CD8+ T cells were also robustly elevated by 5.9 and 2.7 folds respectively. Robust expansion of memory pools by the third dose potentiated greater durability of protective immune responses. Another key finding in this trial was that HCWs with low serological response to two doses were not truly "non-responders" but fully equipped with immune memory that could be quickly recalled by a third dose even 5 months after the second vaccination. Collectively, these data provide insights into the generation of long-term immunological memory by the inactivated vaccine, which could be rapidly recalled and further boosted by a third dose.