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BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, there is an urgent need for safe and effective COVID-19 vaccines to protect children and adolescents. This study aims to provide scientific evidence and recommendations for the application of COVID-19 vaccines in children and adolescents by analyzing the latest studies. METHODS: We systematically searched MEDLINE (accessed through PubMed), Embase, and Web of Science from January 1, 2020, to October 8, 2022. Eligible clinical trials, cohort studies, caseâcontrol studies, and cross-sectional studies with extractable data were included in immunogenicity, effectiveness, and safety analyses. According to the heterogeneity, we chose a fixed-effect model (when I2 ≤ 50) or a random-effects model (when I2 > 50) to pool effect values. RESULTS: A total of 88 articles were included. The seroconversion rates after the first, second, and third doses of the vaccines were 86.10%, 96.52%, and 99.87%, respectively. After the first and second doses, vaccine effectiveness (VE) against severe acute respiratory syndrome coronavirus 2 infection was 42.87% [95% confidence interval (CI) = 27.09%-58.65%] and 63.33% (95% CI = 52.09%-74.56%), respectively. After the first and second doses, VE against COVID-19 was 60.65% (95% CI = 44.80%-76.50%) and 75.77% (95% CI = 63.99%-87.56%), respectively. VE against hospitalization due to COVID-19 after the first and second doses was 72.74% (95% CI = 51.48%-94.01%) and 82.78% (95% CI = 75.78%-89.78%), respectively. The most common adverse events were injection site pain, fatigue/asthenia/tiredness, headache, myalgia/muscle pain, and chills. The incidence rate of myocarditis or pericarditis was 2.42/100,000 people. In addition, the subgroup analysis showed that children aged ≤ 5 years had the lowest incidence of adverse events, and the incidence rate of adverse events was higher for mRNA vaccines than for inactivated vaccines. CONCLUSIONS: COVID-19 vaccines have good immunogenicity, effectiveness, and safety among children and adolescents. We recommend that children and adolescents be vaccinated as soon as possible to protect them and slow the spread of COVID-19.
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BACKGROUND: The immunogenicity and safety of COVID-19 vaccines among people living with human immunodeficiency virus (PLWH) are unclear. We aimed to evaluate the immunogenicity and safety of COVID-19 vaccines among PLWH. METHODS: We systematically searched PubMed, EMBASE, and Web of Science from 1 January 2020 to 28 April 2022 and included observational studies, randomized clinical trials, and non-randomized clinical trials reporting extractable data about the immunogenicity and safety of COVID-19 vaccines among PLWH. RESULTS: A total of 34 eligible studies covering 4517 PLWH were included. The pooled seroconversion rates among PLWH after the first and second doses were 67.51% (95% confident interval (CI) 49.09-85.93%) and 96.65% (95%CI 95.56-97.75%), respectively. The seroconversion was similar between PLWH and healthy controls after the first (risk ratio (RR) = 0.89, 95%CI 0.76-1.04) and the second (RR = 0.97, 95%CI 0.93-1.00) dose. Moreover, the geometric mean titer (GMT) showed no significant difference between PLWH and healthy controls after the first dose (standardized mean difference (SMD) = 0.30, 95%CI -1.11, 1.70) and the second dose (SMD = -0.06, 95%CI -0.18, 0.05). Additionally, the pooled incidence rates of total adverse events among PLWH after the first and the second dose were 46.55% (95%CI 28.29-64.82%) and 30.96% (95%CI 13.23-48.70%), respectively. There was no significant difference in risks of total adverse events between PLWH and healthy controls after the first (RR = 0.86, 95%CI 0.67-1.10) and the second (RR = 0.88, 95%CI 0.68-1.14) dose. CONCLUSIONS: The available evidence suggested that the immunogenicity and safety of COVID-19 vaccines among PLWH were acceptable. There was no significant difference in the seroconversion rates and incidence rates of adverse events of COVID-19 vaccines between PLWH and healthy controls.
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Importance: Several studies were conducted to estimate the average incubation period of COVID-19; however, the incubation period of COVID-19 caused by different SARS-CoV-2 variants is not well described. Objective: To systematically assess the incubation period of COVID-19 and the incubation periods of COVID-19 caused by different SARS-CoV-2 variants in published studies. Data Sources: PubMed, EMBASE, and ScienceDirect were searched between December 1, 2019, and February 10, 2022. Study Selection: Original studies of the incubation period of COVID-19, defined as the time from infection to the onset of signs and symptoms. Data Extraction and Synthesis: Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline, 3 reviewers independently extracted the data from the eligible studies in March 2022. The parameters, or sufficient information to facilitate calculation of those values, were derived from random-effects meta-analysis. Main Outcomes and Measures: The mean estimate of the incubation period and different SARS-CoV-2 strains. Results: A total of 142 studies with 8112 patients were included. The pooled incubation period was 6.57 days (95% CI, 6.26-6.88) and ranged from 1.80 to 18.87 days. The incubation period of COVID-19 caused by the Alpha, Beta, Delta, and Omicron variants were reported in 1 study (with 6374 patients), 1 study (10 patients), 6 studies (2368 patients) and 5 studies (829 patients), respectively. The mean incubation period of COVID-19 was 5.00 days (95% CI, 4.94-5.06 days) for cases caused by the Alpha variant, 4.50 days (95% CI, 1.83-7.17 days) for the Beta variant, 4.41 days (95% CI, 3.76-5.05 days) for the Delta variant, and 3.42 days (95% CI, 2.88-3.96 days) for the Omicron variant. The mean incubation was 7.43 days (95% CI, 5.75-9.11 days) among older patients (ie, aged over 60 years old), 8.82 days (95% CI, 8.19-9.45 days) among infected children (ages 18 years or younger), 6.99 days (95% CI, 6.07-7.92 days) among patients with nonsevere illness, and 6.69 days (95% CI, 4.53-8.85 days) among patients with severe illness. Conclusions and Relevance: The findings of this study suggest that SARS-CoV-2 has evolved and mutated continuously throughout the COVID-19 pandemic, producing variants with different enhanced transmission and virulence. Identifying the incubation period of different variants is a key factor in determining the isolation period.
Subject(s)
COVID-19 , SARS-CoV-2 , Adolescent , Aged , COVID-19/epidemiology , Child , Humans , Infectious Disease Incubation Period , Middle Aged , PandemicsABSTRACT
BACKGROUND: Asymptomatic infections are potential sources of transmission for coronavirus disease 2019, especially during the epidemic of the SARS-CoV-2 Omicron variant. We aimed to assess the percentage of asymptomatic infections among SARS-CoV-2 Omicron variant-positive individuals detected by gene sequencing or specific polymerase chain reaction (PCR). METHODS: We searched PubMed, EMBASE, and Web of Science from 26 November 2021 to 13 April 2022. This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with PROSPERO (CRD42022327894). Three researchers independently extracted data and two researchers assessed quality using pre-specified criteria. The pooled percentage with 95% confidence interval (CI) of asymptomatic infections of SARS-CoV-2 Omicron was estimated using random-effects models. RESULTS: Our meta-analysis included eight eligible studies, covering 7640 Omicron variant-positive individuals with 2190 asymptomatic infections. The pooled percentage of asymptomatic infections was 32.40% (95% CI: 25.30-39.51%) among SARS-CoV-2 Omicron variant-positive individuals, which was higher in the population in developing countries (38.93%; 95% CI: 19.75-58.11%), with vaccine coverage ≥ 80% (35.93%; 95% CI: 25.36-46.51%), with a travel history (40.05%; 95% CI: 7.59-72.51%), community infection (37.97%; 95% CI: 10.07-65.87%), and with a median age < 20 years (43.75%; 95% CI: 38.45-49.05%). CONCLUSION: In this systematic review and meta-analysis, the pooled percentage of asymptomatic infections was 32.40% among SARS-CoV-2 Omicron variant-positive individuals. The people who were vaccinated, young (median age < 20 years), had a travel history, and were infected outside of a clinical setting (community infection) had higher percentages of asymptomatic infections. Screening is required to prevent clustered epidemics or sustained community transmission caused by asymptomatic infections of Omicron variants, especially for countries and regions that have successfully controlled SARS-CoV-2.
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Importance: Asymptomatic infections are potential sources of transmission for COVID-19. Objective: To evaluate the percentage of asymptomatic infections among individuals undergoing testing (tested population) and those with confirmed COVID-19 (confirmed population). Data Sources: PubMed, EMBASE, and ScienceDirect were searched on February 4, 2021. Study Selection: Cross-sectional studies, cohort studies, case series studies, and case series on transmission reporting the number of asymptomatic infections among the tested and confirmed COVID-19 populations that were published in Chinese or English were included. Data Extraction and Synthesis: This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Random-effects models were used to estimate the pooled percentage and its 95% CI. Three researchers performed the data extraction independently. Main Outcomes and Measures: The percentage of asymptomatic infections among the tested and confirmed populations. Results: Ninety-five unique eligible studies were included, covering 29â¯776â¯306 individuals undergoing testing. The pooled percentage of asymptomatic infections among the tested population was 0.25% (95% CI, 0.23%-0.27%), which was higher in nursing home residents or staff (4.52% [95% CI, 4.15%-4.89%]), air or cruise travelers (2.02% [95% CI, 1.66%-2.38%]), and pregnant women (2.34% [95% CI, 1.89%-2.78%]). The pooled percentage of asymptomatic infections among the confirmed population was 40.50% (95% CI, 33.50%-47.50%), which was higher in pregnant women (54.11% [95% CI, 39.16%-69.05%]), air or cruise travelers (52.91% [95% CI, 36.08%-69.73%]), and nursing home residents or staff (47.53% [95% CI, 36.36%-58.70%]). Conclusions and Relevance: In this meta-analysis of the percentage of asymptomatic SARS-CoV-2 infections among populations tested for and with confirmed COVID-19, the pooled percentage of asymptomatic infections was 0.25% among the tested population and 40.50% among the confirmed population. The high percentage of asymptomatic infections highlights the potential transmission risk of asymptomatic infections in communities.