Transmission of SARS-CoV-2 by children: a rapid review, 30 December 2019 to 10 August 2020.

BackgroundThe role of children in the transmission of SARS-CoV-2 during the early pandemic was unclear.AimWe aimed to review studies on the transmission of SARS-CoV-2 by children during the early pandemic.MethodsWe searched MEDLINE, Embase, the Cochrane Library, Europe PubMed Central and the preprint servers medRxiv and bioRxiv from 30 December 2019 to 10 August 2020. We assessed the quality of included studies using a series of questions adapted from related tools. We provide a narrative synthesis of the results.ResultsWe identified 28 studies from 17 countries. Ten of 19 studies on household and close contact transmission reported low rates of child-to-adult or child-to-child transmission. Six studies investigated transmission of SARS-CoV-2 in educational settings, with three studies reporting 183 cases from 14,003 close contacts who may have contracted COVID-19 from children index cases at their schools. Three mathematical modelling studies estimated that children were less likely to infect others than adults. All studies were of low to moderate quality.ConclusionsDuring the early pandemic, it appeared that children were not substantially contributing to household transmission of SARS-CoV-2. School-based studies indicated that transmission rates in this setting were low. Large-scale studies of transmission chains using data collected from contact tracing and serological studies detecting past evidence of infection would be needed to verify our findings.

Alternative clinical specimens for the detection of SARS-CoV-2: A rapid review.

The collection of nasopharyngeal swabs to test for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an invasive technique with implications for patients and clinicians. Alternative clinical specimens from the upper respiratory tract may offer benefits in terms of collection, comfort and infection risk. The objective of this review was to synthesise the evidence for detection of SARS-CoV-2 ribonucleic acid (RNA) using reverse transcription polymerase chain reaction (RT-PCR) tested saliva or nasal specimens compared with RT-PCR tested nasopharyngeal specimens. Searches were conducted in PubMed, Embase, Europe PMC and NHS evidence from December 2019 to 20 July 2020. Eighteen studies were identified; 12 for saliva, four for nasal and two included both specimen types. For saliva-based studies, the proportion of saliva samples testing positive relative to all positive samples in each study ranged from 82.9% to 100%; detection in nasopharyngeal specimens ranged from 76.7% to 100%; positive agreement between specimens for overall detection ranged from 65.4% to 100%. For nasal-based studies, the proportion of nasal swabs testing positive relative to all positive samples in each study ranged from 81.9% to 100%; detection in nasopharyngeal specimens ranged from 70% to 100%; positive agreement between specimens for overall detection ranged from 62.3% to 100%. The results indicate an inconsistency in the detection of SARS-CoV-2 RNA in the specimen types included, often with neither the index nor the reference of interest detecting all known cases. Depending on the test environment, these clinical specimens may offer a viable alternative to standard. However, at present the evidence is limited, of variable quality, and relatively inconsistent.

Immune response following infection with SARS-CoV-2 and other coronaviruses: A rapid review.

In this review, we systematically searched and summarized the evidence on the immune response and reinfection rate following SARS-CoV-2 infection. We also retrieved studies on SARS-CoV and MERS-CoV to assess the long-term duration of antibody responses. A protocol based on Cochrane rapid review methodology was adhered to and databases were searched from 1/1/2000 until 26/5/2020. Of 4744 citations retrieved, 102 studies met our inclusion criteria. Seventy-four studies were retrieved on SARS-CoV-2. While the rate and timing of IgM and IgG seroconversion were inconsistent across studies, most seroconverted for IgG within 2 weeks and 100% (N = 62) within 4 weeks. IgG was still detected at the end of follow-up (49-65 days) in all patients (N = 24). Neutralizing antibodies were detected in 92%-100% of patients (up to 53 days). It is not clear if reinfection with SARS-CoV-2 is possible, with studies more suggestive of intermittent detection of residual RNA. Twenty-five studies were retrieved on SARS-CoV. In general, SARS-CoV-specific IgG was maintained for 1-2 years post-infection and declined thereafter, although one study detected IgG up to 12 years post-infection. Neutralizing antibodies were detected up to 17 years in another study. Three studies on MERS-CoV reported that IgG may be detected up to 2 years. In conclusion, limited early data suggest that most patients seroconvert for SARS-CoV-2-specific IgG within 2 weeks. While the long-term duration of antibody responses is unknown, evidence from SARS-CoV studies suggest SARS-CoV-specific IgG is sustained for 1-2 years and declines thereafter.

SARS-CoV-2 detection, viral load and infectivity over the course of an infection.

OBJECTIVES: To summarise the evidence on the detection pattern and viral load of SARS-CoV-2 over the course of an infection (including any asymptomatic or pre-symptomatic phase), and the duration of infectivity. METHODS: A systematic literature search was undertaken in PubMed, Europe PubMed Central and EMBASE from 30 December 2019 to 12 May 2020. RESULTS: We identified 113 studies conducted in 17 countries. The evidence from upper respiratory tract samples suggests that the viral load of SARS-CoV-2 peaks around symptom onset or a few days thereafter, and becomes undetectable about two weeks after symptom onset; however, viral loads from sputum samples may be higher, peak later and persist for longer. There is evidence of prolonged virus detection in stool samples, with unclear clinical significance. No study was found that definitively measured the duration of infectivity; however, patients may not be infectious for the entire duration of virus detection, as the presence of viral ribonucleic acid may not represent transmissible live virus. CONCLUSION: There is a relatively consistent trajectory of SARS-CoV-2 viral load over the course of COVID-19 from respiratory tract samples, however the duration of infectivity remains uncertain.