Table 1.
Characteristics of the included studies.
| Author | Country | Age, years [mean (±SD)/median (IRQ)] | Study Type | Type of test | Major findings |
|---|---|---|---|---|---|
| Family cluster | |||||
| Chan et al., 20208 | China | Family: 36-60 | Cohort | RT-PCR | Supports person-to-person transmission between family |
| Child: 10 | |||||
| Chen et al., 20209 | China | 8.5 ± 0.17 | Case report | RT-PCR | The ability of COVID-19 transmission during the asymptomatic period even after negative viral testing |
| Lu et al., 201910 | China | 8 | Case report | RT-PCR | Supports rigorous investigation in the combination of various testing methods for asymptomatic COVID-19 cases |
| Qian et al., 202011 | China | 6 | Brief report | RT-PCR | Variation in clinical manifestation across individuals was observed |
| Ye et al., 202012 | China | 38 ± 18.38 | Cohort | RT-PCR | Possibility of COVID-19 transmission by the asymptomatic carrier during the incubation period |
| Bai et al., 20207 | China | 20 | Cohort | RT-PCR | Support asymptomatic transmission through a family contact |
| Xie et al., 202156 | China | >18 | Cohort | RT-PCR | Handwashing, social distancing should be done |
| Zhang et al., 202157 | China | >18 | Cohort | RT-PCR | Asymptomatic patients can transmit the disease and improve protective measures. |
| Adults | |||||
| Tian et al., 202021 | China | 47.5 | Cohort | RT-PCR | Early isolation and quarantine for close contacts to prevent asymptomatic transmission |
| Kim et al., 202017 | Korea | 26 (22–47) | Research note | RT-PCR | Supports social distancing to prevent asymptomatic transmission |
| Kong et al., 20208 | China | 37.7 (±19) | Cohort | RT-PCR | Suggest rigorous epidemiological history and chest CT scan as a practical tool to identify the asymptomatic COVID-19 cases in the community |
| Yin et al., 202022 | China | – | Cohort | RT-PCR | No difference in the transmission rate of COVID-19 between asymptomatic and symptomatic cases |
| Meng et al., 202055 | China | 42.60 (±16.56) | Cohort | RT-PCR | Suggest chest CT scan as a vital tool to screen the asymptomatic COVID-19 cases in the community |
| Al Hosani et al., 201915 | UAE | 37 (30–45) | Cohort | RT-PCR | No transmission among household contacts after the implication of strong isolation policies |
| He et al., 202016 | China | – | Cohort | RT-PCR | Significantly smaller transmissibility of asymptomatic cases than symptomatic |
| Qiu et al., 202020 | China | 43 (8–84) | Cohort | RT-PCR | Suggested transmission occurred after 14 days quarantine periods |
| Zhou et al., 202024 | China | – | Short communication | RT-PCR | Recommended rigorous epidemiological history and nucleic acid testing |
| Park et al., 202019 | Korea | 38 (20–0) | Report | RT-PCR | Supports contact tracing, testing and increasing quarantine to prevent asymptomatic COVID-19 transmission in the community |
| De laval et al., 202161 | France | 40 (24–59) | Cohort | RT-PCR | The median incubation day was 4 (1–13) days. |
| Wong et al., 202034 | Brunei | – | Cohort | RT-PCR | Proposes differentiated testing strategies to account for different transmission risk |
| Huang et al., 202060 | China | – | Cohort | RT-PCR | To identify the presence of asymptomatic carriers as early as possible in the community. Infection occurs during the incubation period of asymptomatic cases. |
| Sugano et al., 202058 | Japan | – | Cohort | RT-PCR | Possibility of asymptomatic transmission and the period from exposure to illness ranged from 2 to 17 days. |
| Nsekye et al., 202162 | Rawanda | – | Cohort | RT-PCR | Contact tracing and testing should be done. |
| Children | |||||
| Hu et al., 202025 | China | <15 | Cohort | RT-PCR | Suggest close contact tracing and nucleic acid testing to identify the asymptomatic COVID-19 tracing the community |
| Qiu et al., 201926 | China | 8.3 (±3.5) | Cohort | RT-PCR | Possibility of asymptomatic COVID-19 transmission by close contacts |
| Tan et al., 20201 | China | – | Cohort | RT-PCR | Possibility of asymptomatic COVID-19 transmission by intrafamilial contact |
| Sun et al., 202059 | China | 5.8 | Cohort | RT-PCR | Both nasopharyngeal and anal swabs should be confirmed negative viral load before declaring full recovery to avoid oral-faecal transmission. |
| Health care Workers | |||||
| Kimball et al., 202027 | USA | – | Report | RT-PCR | Reported rapid transmission among health care worker |
| Schoierzeck et al., 202029 | Germany | 48 | Cohort | RT-PCR | Suggest nucleic acid testing for asymptomatic COVID-19 cases |
| Lucar et al., 202028 | USA | >18 | Cohort | RT-PCR | transmission reported because of prolonged surgery done on asymptomatic COVID-19 case |
| Traveller aged >18 years | |||||
| COVID-19 NERC, 202030 | Korea | >18 | Cohort | RT-PCR | Supports asymptomatic transmission with minor symptoms |
| Mizumoto et al., 202032 | Japan | >18 | Rapid communication | RT-PCR | Support social distancing to prevent the asymptomatic transmission |
| Wan et al., 202033 | China | >18 | Short communication | RT-PCR | Possibility of asymptomatic transmission after 14 days quarantine from asymptomatic COVID-19 case |
| Wong et al., 202034 | Brunei | – | Rapid communication | RT-PCR | Support social distancing & nucleic acid testing of asymptomatic COVID-19 case |
| Le et al., 202054 | China | – | Abstract | – | Support asymptomatic COVID-19 viral transmissibility in the absence of signs and symptoms |
Note: - Missing values (mean/median values were not reported).
IQR, interquartile range; RT-PCT, reverse transcription-polymerase chain reaction.