Protective Effect of Inactivated COVID-19 Vaccines against Omicron BA.2 Infection in Guangzhou: A Test-Negative Case-Control Real-World Study.

This study aims to explore the relationship between the doses of inactivated COVID-19 vaccines received and SARS-CoV-2 Omicron infection in the real-world setting, so as to preliminarily evaluate the protective effect induced by COVID-19 vaccination. We conducted a test-negative case-control study and recruited the test-positive cases and test-negative controls in the outbreak caused by Omicron BA.2 in April 2022 in Guangzhou, China. All the participants were 3 years and older. The vaccination status between the case group and the control group was compared in the vaccinated and all participants, respectively, to estimate the immune protection of inactivated COVID-19 vaccines. After adjusting for sex and age, compared with a mere single dose, full vaccination of inactivated COVID-19 vaccines (OR = 0.191, 95% CI: 0.050 to 0.727) and booster vaccination (OR = 0.091, 95% CI: 0.011 to 0.727) had a more superior protective effect. Compared with one dose, the second dose was more effective in males (OR = 0.090), as well as two doses (OR = 0.089) and three doses (OR = 0.090) among individuals aged 18-59. Whereas, when compared with the unvaccinated, one dose (OR = 7.715, 95% CI: 1.904 to 31.254) and three doses (OR = 2.055, 95% CI: 1.162 to 3.635) could contribute to the increased risk of Omicron infection after adjusting for sex and age. Meanwhile, by contrast with unvaccinated individuals, the result of increased risk was also manifested in the first dose in males (OR = 12.400) and one dose (OR = 21.500), two doses (OR = 1.890), and a booster dose (OR = 1.945) in people aged 18-59. In conclusion, the protective effect of full and booster vaccination with inactivated COVID-19 vaccines exceeded the incomplete vaccination, of which three doses were more effective. Nevertheless, vaccination may increase the risk of Omicron infection compared with unvaccinated people. This may result from the transmission traits of BA.2, the particularity and stronger protection awareness of the unvaccinated population, as well as the ADE effect induced by the decrease of antibody titers after a long time of vaccination. It is crucial to explore this issue in depth for the formulation of future COVID-19 vaccination strategies.

Impact of Vaccination and Control Measures on the Fatality of COVID-19: An Ecological Study.

BACKGROUND: During the COVID-19 pandemic, reducing the case fatality rate (CFR) becomes an urgent goal. OBJECTIVE: This study explored the effect of vaccination and variants on COVID-19 fatality and provide a basis for the adjustment of control measures. METHODS: This study collected epidemiological information on COVID-19 from January to October 2021. By setting different lag times, we calculated the adjusted CFR. The Spearman correlation coefficient and beta regression were used to explore factors that may affect COVID-19 fatality. RESULTS: Every 1% increase in the percentage of full vaccinations may reduce the 3 weeks lagging CFR by 0.66%. Increasing the restrictions on internal movement from level 0 to 1, restrictions on international travel controls from level 2 to 3, and stay-at-home restrictions from level 0 to 2 were associated with an average reduction in 3 weeks lagging CFR of 0.20%, 0.39%, and 0.36%, respectively. Increasing strictness in canceling public events from level 0 to 1 and 2 may reduce the 3 weeks lagging CFR by 0.49% and 0.37, respectively. Increasing the severity of school and workplace closures from level 1 or level 0 to 3 may increase the 3 weeks lagging CFR of 0.39% and 0.83, respectively. Every 1-point increase in the Global Health Security (GHS) index score may increase the 3 weeks lagging CFR by 0.12%. CONCLUSION: A higher percentage of full vaccinations, higher levels of internal movement restrictions, international travel control restrictions, cancelations of public events, and stay-at-home restrictions are factors that may reduce the adjusted CFR.

Neutralization Effect of Sera against Delta and Omicron in Patients Recovering from COVID-19 and Inactivated Vaccine Recipients.

This study aims to analyze the serum neutralization capacity against Delta and Omicron variants in three clusters of individuals, including those who had recovered from COVID-19 and those who had received two and three doses of inactivated vaccine. Pseudovirus neutralization tests were performed on serum samples. The neutralizing titers between different groups were compared using the Wilcoxon's signed-rank test. Among the two-dose vaccinees, the neutralization titers of the Omicron variant were reduced by approximately 3.1-fold compared to the wild-type virus (p < 0.05). Meanwhile, among the three-dose vaccinees, the neutralization titers for Delta and Omicron variants were 3.5-fold (p < 0.05) and 5.0-fold (p < 0.05) lower, respectively, as compared to the wild-type virus. In addition, among the recovering patients, the neutralization titers for Delta and Omicron variants were 3.9-fold (p < 0.05) and 29.1-fold (p < 0.05) lower, respectively, as compared to the wild-type virus. Overall, only 12.0% (11/92) of participants showed neutralizing titers against Omicron above the detection limit. The ability to neutralize wild-type pseudovirus was significantly boosted in three-dose vaccinees as compared to two-dose vaccinees. Sera from recovered patients showed greater neutralizing titers for the wild-type and Delta pseudoviruses than the two- and three-dose inactivated vaccine groups. The present study revealed a loss of neutralizing activity against the Omicron variant in almost all samples. Moreover, the immunization effect obtained through natural infection is more robust than that from the active immunization method of vaccination.

Effect of Vaccination Time Intervals on SARS-COV-2 Omicron Variant Strain Infection in Guangzhou: A Real-World Matched Case-Control Study.

In April 2022, a COVID-19 outbreak caused by the Omicron variant emerged in Guangzhou. A case-control study was conducted to explore the relationship between vaccination intervals and SARS-CoV-2 infection in the real world. According to the vaccination dose and age information of the cases, a 1:4 matched case-control sample was established, finally including n = 242 for the case group and n = 968 for the control group. The results indicated that among the participants who received three vaccine doses, those with an interval of more than 300 days between the receipt of the first vaccine dose and infection (or the first contact with a confirmed case) were less likely to be infected with SARS-CoV-2 than those with an interval of less than 300 days (OR = 0.67, 95% CI = 0.46-0.99). After age-stratified analysis, among participants aged 18-40 years who received two doses of vaccine, those who received the second dose more than 30 days after the first dose were less likely to be infected with SARS-CoV-2 (OR = 0.53, 95% CI = 0.30-0.96). Our findings suggest that we need to extend the interval between the first dose and the second dose and further explore the optimal interval between the first and second and between the second and third doses in order to improve vaccine efficacy.

Does potential antibody-dependent enhancement occur during SARS-CoV-2 infection after natural infection or vaccination? A meta-analysis.

Coronavirus disease 2019 (COVID-19) continues to constitute an international public health emergency. Vaccination is a prospective approach to control this pandemic. However, apprehension about the safety of vaccines is a major obstacle to vaccination. Amongst health professionals, one evident concern is the risk of antibody-dependent enhancement (ADE), which may increase the severity of COVID-19. To explore whether ADE occurs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and increase confidence in the safety of vaccination, we conducted a meta-analysis to investigate the relationship between post-immune infection and disease severity from a population perspective. Databases, including PubMed, EMBASE, Chinese National Knowledge Infrastructure, SinoMed, Scopus, Science Direct, and Cochrane Library, were searched for articles on SARS-CoV-2 reinfection published until 25 October 2021. The papers were reviewed for methodological quality, and a random effects model was used to analyse the results. Heterogeneity was assessed using the I2 statistic. Publication bias was evaluated using a funnel plot and Egger's test. Eleven studies were included in the final meta-analysis. The pooled results indicated that initial infection and vaccination were protective factors against severe COVID-19 during post-immune infection (OR = 0.55, 95%CI = 0.31-0.98). A subgroup (post-immune infection after natural infection or vaccination) analysis showed similar results. Primary SARS-CoV-2 infection and vaccination provide adequate protection against severe clinical symptoms after post-immune infection. This finding demonstrates that SARS-CoV-2 may not trigger ADE at the population level.

Association between Mutations in Papain-like Protease (PLpro) of SARS-CoV-2 with COVID-19 Clinical Outcomes.

Papain-like protease (PLpro) is important for the replication and transcription of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to reveal the PLpro mutations associated with the clinical outcomes of patients. Due to the importance of the S protein in the pathogenicity of SARS-CoV-2, the mutation of the S protein was also analyzed in this study. After downloading the data from the Global Initiative on Sharing Avian Influenza Data (GISAID) database, samples were divided into two groups on the basis of patient status, namely, recovered and dead groups. This study performed a univariate analysis and further explored the association of mutations with patient outcomes through multivariate logistic regression analysis. A total of 138,492 samples were used for analysis. The patients had a mean age of 43.66 ± 21.56 years, and 51.3% of them were female. Multivariate logistic regression results showed that, compared with men, women had a lower risk of dying from coronavirus disease 2019 (COVID-19) (OR = 0.687, 95%CI: 0.638-0.740). Compared with patients aged 17 years and younger, patients aged 18-64 years (OR = 2.864, 95%CI: 1.982-4.139) and patients over 65 years old (OR = 19.135, 95%CI: 13.280-27.572) had a higher risk of death after infection. Compared with the wild type, P78L (OR = 5.185, 95%CI: 2.763-9.730) and K233Q (OR = 5.154, 95%CI: 1.442-18.416) in PLpro were associated with an increased risk of death. A synergistic interaction existed between age and mutations A146D and P78L. The results of the multivariate logistic regression analysis of the data on vaccinated patients demonstrated that, compared with the wild type, the P78L (OR = 3.376, 95%CI: 2.040-5.585) mutation was associated with an increased risk of death. In conclusion, compared with the wild-type PLpro protein, the P78L and K233Q mutations may increase the risk of death in infected individuals. In addition, a synergistic effect existed between age and P78L and K233Q that increased the risk of death in older patients.

Effectiveness of COVID-19 Vaccine Booster Shot Compared with Non-Booster: A Meta-Analysis.

The analysis of the effectiveness of booster shots compared with primary vaccination is extremely vital. This paper aimed to summarize the results of all available evidence studies on the effectiveness of booster vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Articles published up to 21 June 2022 were systematically searched through PubMed and EMBASE databases. The searched studies were independently assessed for quality using the Newcastle-Ottawa Scale. Results: Seven studies (nine datasets) met the criteria and were included in this study. The pooled results demonstrated a 71% (OR = 0.29, 95% CI = 0.17-0.48) reduction in SARS-CoV-2 infection rates among subjects who received a booster shot compared with those who did not receive a booster shot of coronavirus disease (COVID-19) vaccine. In addition, this analysis emphasized that during the period when the Delta variant was predominant, subjects who received the booster shot showed an 82% (OR = 0.18, 95% CI = 0.13-0.25) reduction in infection rates. Moreover, during the period of dominance of the Omicron variant, subjects who received the booster vaccination displayed a 47% (OR = 0.53, 95% CI = 0.35-0.81) reduction in infection rates. This finding confirmed that booster vaccination against the Omicron variant is significantly less effective than that against the Delta variant. In pandemic periods, correlations between the dominant variant and the efficacy of the COVID-19 vaccine booster should be considered when making vaccine booster plans.

Transplacental Transfer of Maternal Antibody against SARS-CoV-2 and Its Influencing Factors: A Review.

Since the beginning of the coronavirus disease 2019 (COVID-19) outbreak, the disease has rapidly become a global threat. The constant emergence of new variants has increased the difficulty of controlling this disease. Vaccination is still considered the most effective method to prevent COVID-19. Vaccination has expanded to include children aged 3-17 years old, and some countries have lowered the age of vaccination to 6 months (for example, the United States). However, children under 3 years old are still not able to be vaccinated in most countries. In this study, we summarize the COVID-19 vaccination status in pregnant women, comprehensively elaborate on the status of maternal immune response and maternal antibody transfer after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination, and further analyze the possible influencing factors of maternal antibody transfer according to the currently available evidence on the topic. It was concluded that pregnant women develop an immune response and produce antibodies that can be transmitted through the placenta after vaccination, but more data are needed to determine the transfer rate and duration of these maternal antibodies and potential factors. The results provide a scientific basis for studying the protective effect of maternal antibodies on infants, formulating a vaccination strategy for pregnant women, and preventing SARS-CoV-2 infection in infants.

Effectiveness of inactivated SARS-CoV-2 vaccines against the Delta variant infection in Guangzhou: a test-negative case-control real-world study.

The effectiveness of inactivated SARS-CoV-2 vaccines against the Delta variant, which has been associated with greater transmissibility and virulence, remains unclear. We conducted a test-negative case-control study to explore the vaccine effectiveness (VE) in real-world settings. We recruited participants aged 18-59 years who consisted of SARS-CoV-2 test-positive cases (n = 74) and test-negative controls (n = 292) during the outbreak of the Delta variant in May 2021 in Guangzhou city, China. Vaccination status was compared to estimate The VE of SARS-CoV-2 inactivated vaccines. A single dose of inactivated SARS-CoV-2 vaccine yielded the VE of only 13.8%. After adjusting for age and sex, the overall VE for two-dose vaccination was 59.0% (95% confidence interval: 16.0% to 81.6%) against coronavirus disease 2019 (COVID-19) and 70.2% (95% confidence interval: 29.6-89.3%) against moderate COVID-19 and 100% against severe COVID-19 which might be overestimated due to the small sample size. The VE of two-dose vaccination against COVID-19 reached 72.5% among participants aged 40-59 years, and was higher in females than in males against COVID-19 and moderate diseases. While single dose vaccination was not sufficiently protective, the two-dose dosing scheme of the inactivated vaccines was effective against the Delta variant infection in real-world settings, with the estimated efficacy exceeding the World Health Organization minimal threshold of 50%.

Predictive analysis and countermeasures in response to COVID-19 epidemic in 2020-2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a natural emerging virus, with rapid virus replication, wide cell tropism, and strong survival ability. Its epidemic characteristics are similar to those of influenza virus. Asymptomatic infections are widespread in a covert way, and the virus has adapted to human population, making it difficult to control the transmission. The global epidemic in 2020/2021 may further deteriorate before the SARS-CoV-2 vaccines are widely applied and show protective effectiveness, and China will still face the risk of continuous overseas multi-channel import and local outbreaks or recurrence of the epidemic. Therefore, it is necessary to carry out further surveillance about the prevalence and infection of SARS-CoV-2 in the population and the corresponding environment of the high-risk areas in China, and establish a national super mobile SARS-CoV-2 detection network laboratory for performing ultra-large-scale testing tasks;implement differentiated vaccination strategies and closely follow up and monitor the effectiveness and efficiency of vaccination;and continue to strengthen effective public health measures such as wearing masks, washing hands frequently, keeping social distances, opening windows frequently, and reducing gatherings. The coronavirus disease 2019 (COVID-19) epidemic warns us once again that the continuous emergence of new infectious diseases caused by unknown pathogens of wild animal origin has become the new normal status. It is necessary to systematically carry out unknown microbial discovery and reverse pathogenic etiology research in a prospective manner, and actively defend against emerging infectious diseases in the future.

Willingness to Receive SARS-CoV-2 Vaccination and Associated Factors among Chinese Adults: A Cross Sectional Survey.

Vaccination is a key strategy to prevent the pandemic caused by the coronavirus disease 2019 (COVID-19). This study aims to investigate the willingness of Chinese adults to be vaccinated against COVID-19 and further explore the factors that may affect their willingness. We used a self-design anonymous questionnaire to conduct an online survey via the Sojump. A total of 1009 valid questionnaires were analyzed. The age of the participants ranged from 18 to 74. Among them, 609 (60.4%, 95%CI: 57.4-63.4%) were willing to receive the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. Logistic regression analysis results showed that the age of 30-49 (OR = 2.042, 95%CI: 1.098-3.799), universities and colleges education (OR = 1.873, 95% CI = 1.016-3.451), master degree or above education (OR = 1.885, 95%CI = 1.367-2.599), previous influenza vaccination history (OR = 2.176, 95%CI: 1.474-3.211), trust in the effectiveness of the vaccine (OR = 6.419, 95%CI: 3.717-11.086), and close attention to the latest news of the vaccine (OR = 1.601, 95%CI: 1.046-2.449) were facilitative factors that affected their willingness to be vaccinated. More than half of the adults in China would be willing to receive a SARS-CoV-2 vaccine. Middle-aged people with higher education, those who had been vaccinated against influenza, and those who believed that COVID-19 vaccine was effective and paid close attention to it were more willing to be vaccinated. Our findings can provide reference for the implementation of vaccination and the prevention of COVID-19 in China. More studies are needed after the vaccine is launched.

Retrospective study identifies infection related risk factors in close contacts during COVID-19 epidemic.

OBJECTIVES: This study aimed to compare the risk of infection of children with that of adults and to explore risk factors of infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) by following up close contacts of COVID-19 patients. METHOD: The retrospective cohort study was performed among close contacts of index cases diagnosed with COVID-19 in Guangzhou, China. Demographic characteristics, clinical symptoms and exposure information were extracted. Logistic regression analysis was employed to explore the risk factors. The restricted cubic spline was conducted to examine to the dose-response relationship between age and SARS-CoV-2 infection. RESULTS: The secondary attack rate (SAR) was 4.4% in 1,344 close contacts. The group of household contacts (17.2%) had the highest SAR. The rare-frequency contact (p < 0.001) and moderate-frequency contact (p < 0.001) were associated with lower risk of infection. Exposure to index cases with dry cough symptoms was associated with infection in close contacts (p = 0.004). Compared with children, adults had a significantly increased risk of infection (p = 0.014). There is a linear positive correlation between age and infection (p = 0.001). CONCLUSIONS: Children are probably less susceptible to COVID-19. Close contacts with frequent contact with patients and those exposed to patients with cough symptoms are associated with an increased risk of infection.

Epidemiological characteristics of respiratory viruses in patients with acute respiratory infections during 2009-2018 in southern China.

BACKGROUND: Acute respiratory infections (ARIs) remain a significant public threat with high morbidity and mortality worldwide; viruses are significant pathogens that cause ARIs. This study was conducted to better understand the epidemiological characteristics of respiratory viruses circulating in southern China. METHODS: We collected 22,680 respiratory samples from ARI patients in 18 hospitals in southern China during 2009-2018; seven common respiratory viruses including Flu, RSV, PIV, hMPV, ADV, HCoV, and HBoV were screened using in-house real-time PCR. RESULTS: Of all samples, 9760 ARI cases (9760/22680, 43.03%) tested positive for the seven common respiratory viruses. The most detected virus was Flu (14.15%), followed by RSV (10.33%) and PIV (5.43%); Flu-A, PIV3, and HCoV-OC43 were the predominant subtypes. Although most of the viruses were detected in male inpatients, Flu was more likely detected in female outpatients. Flu infection was more likely to cause URTI (upper respiratory tract infection), whereas RSV infection was more likely to cause pneumonia and bronchitis. The prevalence of Flu was particularly high in 2009. The epidemic level was found notably high in 2014-2018 for RSV, in 2016-2018 for PIV, in the summer of 2018 for ADV, in the summer of 2016 and winter of 2018 for HCoV, and in the summer of 2011 and autumn of 2018 for HBoV. The co-detection rate of the seven viruses was 4.70%; RSV, PIV, and Flu were the most commonly co-detected viruses. CONCLUSIONS: This work demonstrates the epidemiological characteristics of seven common respiratory viruses in ARI patients in southern China.