Impact of non-pharmaceutical interventions on circulating respiratory viruses during the COVID-19 pandemic in Turkey.

BACKGROUND: Non-pharmaceutical interventions (NPIs) applied to limit the SARS-CoV-2 pandemic also affect the circulation and seasonal characteristics of other respiratory viruses. OBJECTIVES: Assess the impact of NPIs on the spread and seasonal characteristics of non-SARS-CoV-2 respiratory viruses and examine viral respiratory co-infections. DESIGN: Retrospective cohort SETTING: Single center in Turkey. PATIENTS AND METHODS: Syndromic multiplex viral polymerase chain reaction (mPCR) panel results of patients admitted to the Ankara Bilkent City Hospital with symptoms of acute respiratory tract infection between April 1, 2020 and October 30, 2022 were evaluated. Two study periods before and after 1 July 2021, when the restrictions were discontinued, were statistically analyzed and compared to determine the effect of NPIs on circulating respiratory viruses. MAIN OUTCOME MEASURES: Prevalence of respiratory viruses as determined by syndromic mPCR panel. SAMPLE SIZE: 11300 patient samples were evaluated. RESULTS: At least one respiratory tract virus was detected in 6250 (55.3%) patients. Of these, at least one respiratory virus was detected in 5% in the first period (between April 1, 2020 and June 30, 2021, when NPIs were applied), and in 95% in the second period (between July 1, 2021 and October 30, 2022, when NPIs were relaxed). After the removal of NPIs, there was a statistically significant increase in hRV/EV, RSV-A/B, Flu A/H3, hBoV, hMPV, PIV-1, PIV-4, hCoV-OC43, PIV-2 and hCoV-NL63 (P<.05). In the 2020-2021 season, when strict NPIs were applied, all respiratory viruses evaluated did not have the usual seasonal peak and there were no seasonal influenza epidemics during this period. CONCLUSIONS: NPIs resulted in a dramatic decrease in the prevalence of respiratory viruses and notable disruption of seasonal characteristics. LIMITATIONS: Single-center study and retrospective. CONFLICT OF INTEREST: None.

One-Year Post-Vaccination Longitudinal Follow-Up of Quantitative SARS-CoV-2 Anti-Spike Total Antibodies in Health Care Professionals and Evaluation of Correlation with Surrogate Neutralization Test.

Numerous vaccines have been generated to decrease the morbidity and mortality of COVID-19. This study aims to evaluate the immunogenicity of the heterologous boosts by BioNTech against homologous boosts by CoronaVac at three-month intervals in two health care worker (HCW) cohorts, with or without prior COVID-19, for one year post-vaccination. This is a prospective cohort study in which the humoral responses of 386 HCWs were followed-up longitudinally in six main groups according to their previous COVID-19 exposure and vaccination status. Anti-SARS-CoV-2 spike-RBD total antibody levels were measured and SARS-CoV-2 neutralization antibody (NAbs) responses against the ancestral Wuhan and the Omicron variant were evaluated comparatively using international standard serum for Wuhan and Omicron, as well as with the aid of a conversion tool. The anti-SARS-CoV-2 spike-RBD total Ab and Nab difference between with and without prior COVID-19, three months after two-dose primary vaccination with CoronaVac, was statistically significant (p = 0.001). In the subsequent follow-ups, this difference was not observed between the groups. Those previously infected (PI) and non-previously infected (NPI) groups receiving BioNTech as the third dose had higher anti-SARS-CoV-2 spike total Ab levels (14.2-fold and 17.4-fold, respectively, p = 0.001) and Nab responses (against Wuhan and Omicron) than those receiving CoronaVac. Ab responses after booster vaccination decreased significantly in all groups at the ninth-month follow-up (p < 0.05); however, Abs were still higher in all booster received groups than that in the primary vaccination. Abs were above the protective level at the twelfth-month measurement in the entire of the second BioNTech received group as the fourth dose of vaccination. In the one-year follow-up period, the increased incidence of COVID-19 in the groups vaccinated with two or three doses of CoronaVac compared with the groups vaccinated with BioNTech as a booster suggested that continuing the heterologous CoronaVac/BioNTech vaccination, revised according to current SARS-CoV-2 variants and with at least a six-month interval booster would be an effective and safe strategy for protection against COVID-19, particularly in health care workers.

Comparison of clinical characteristics of wild-type SARS-CoV-2 and Omicron.

OBJECTIVE: This study aimed to investigate the effect of mutations by comparing wild-type SARS-CoV-2 and Omicron regarding clinical features in patients with COVID-19. It also aimed to assess whether SARS-CoV-2 cycle threshold value could predict COVID-19 severity. METHODS: A total of 960 wild-type and 411 Omicron variant patients with positive results in SARS-CoV-2 real-time reverse transcriptase polymerase chain reaction test from oropharyngeal and/or nasopharyngeal samples during their hospital admissions were included in this retrospective study. The reference symptoms of the patients were obtained from the hospital database. The correlation between chest computed tomography findings and the "cycle threshold" of patients with wild-type SARS-CoV-2 was assessed. RESULTS: Cough, fever, shortness of breath, loss of taste and smell, and diarrhea were found to be statistically significantly higher (p=0.001; 0.001; 0.001; 0.001; and 0.006; respectively) in the wild-type cohort, while in the Omicron cohort, sore throat and headache were found to be statistically significantly higher (p=0.001 and 0.003, respectively). An inverse relationship was found between chest computed tomography findings and viral load. CONCLUSION: This study revealed that the Omicron variant tended to infect predominantly the upper respiratory tract and showed decreased lung infectivity, and the disease progressed with a milder clinical course. Therefore, the study showed that the tropism of the virus was changed and the viral phenotype was affected. It was also found that SARS-CoV-2 viral load did not predict COVID-19 severity in patients with wild-type SARS-CoV-2.

Evaluation of antibody response after COVID-19 vaccination of healthcare workers.

The common goal of all vaccines developed against COVID-19, although they have been designed with different methods, is to develop an effective immunity and antibody response against SARS-CoV-2. However, the postvaccination immune response and antibody levels differ between individuals. This study examined the relationship between postvaccine seropositivity rates, age, gender, smoking, and body mass index (BMI), and antibody titers. A total of 314 healthcare workers (HCW) who were not previously infected with COVID-19 and who had received two doses of CoronaVac inactivated vaccine participated in the study. Seropositivity against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein was measured from the participants 4 weeks after the second dose of vaccine using the electrochemiluminescence (ECLIA) method. In addition, the antibody developed against the nucleocapsid protein (NCP) was evaluated and compared using Elecsys Anti-SARS-CoV-2 kit. One hundred and eighty-one of the participants were female (57.6%) with a median age of 39 (interquartile range [IQR], 10) and 133 (42.4%) were male with a median age of 41 (IQR, 11). 99.6% of the volunteers developed seropositivity 4 weeks after the second dose of vaccine. It was also observed that the rate of RBD protein antibody titer was >250 U/ml in smokers, which is quite low compared to nonsmokers (p = 0.032), and that high RBD antibody titers were proportionally lower in obese participants, according to BMI values, compared to those with normal BMI (49.5% and 9.9%). It was observed that seropositivity developed in almost all participants after the CoronaVac vaccine. However, it was determined that the antibody titer measured varied depending on factors such as smoking, BMI, and duration.