The variant of concern (VOC) B.1.1.7 appears to have substantially increased transmissibility compared to other variants and has grown quickly to become the dominant variant in much of the UK.
Initial assessment by PHE of disease severity through a matched case-control study reported no significant difference in the risk of hospitalization or death in people infected with confirmed B.1.1.7 infection versus infection with other variants.
Several new analyses are however consistent in reporting increased disease severity in people infected with VOC B.1.1.7 compared to people infected with non-VOC virus variants.
There have been several independent analyses of SGTF and non-SGTF cases identified through Pillar 2 testing linked to the PHE COVID-19 deaths line list:
An updated PHE matched cohort analysis has reported a death risk ratio for VOC- infected individuals compared to non-VOC of 1.65 (95%CI 1.21-2.25).
There are several limitations to these datasets including representativeness ofdeath data (<10% of all deaths are included in some datasets), power, potential biases in case ascertainment and transmission setting.
Based on these analyses, there is a realistic possibility that infection with VOC B.1.1.7 is associated with an increased risk of death compared to infection with non-VOC viruses.
It should be noted that the absolute risk of death per infection remains low.
9. An analysis of CO-CIN data has not identified an increased risk of death in hospitalized VOC B.1.1.7 cases. However, increased severity may not necessarily be reflected by increased in-hospital death risk.
Since the time lag from infection to hospitalisation and death is relatively long, data will accrue in coming weeks, at which time the analyses will become more definitive.
Victor Chernozhukov, Hiroyuki Kasahara, & Paul Schrimpf
Abstract: This paper empirically examines how the opening of K-12 schools and colleges is associated with the spread of COVID-19 using county-level panel data in the United States. Using data on foot traffic and K-12 school opening plans, we analyze how an increase in visits to schools and opening schools with different teaching methods (in-person, hybrid, and remote) is related to the 2-weeks forward growth rate of confirmed COVID-19 cases. Our debiased panel data regression analysis with a set of county dummies, interactions of state and week dummies, and other controls shows that an increase in visits to both K-12 schools and colleges is associated with a subsequent increase in case growth rates. The estimates indicate that fully opening K-12 schools with in-person learning is associated with a 5 (SE = 2) percentage points increase in the growth rate of cases. We also find that the positive association of K-12 school visits or in-person school openings with case growth is stronger for counties that do not require staff to wear masks at schools. These results have a causal interpretation in a structural model with unobserved county and time confounders. Sensitivity analysis shows that the baseline results are robust to timing assumptions and alternative specificatio
Forbes et al.
Background: Close contact with children may provide cross-reactive immunity to SARs-CoV-2 due to more frequent prior coryzal infections from seasonal coronaviruses. Alternatively, close contact with children may increase risk of SARs-CoV-2 infection. We investigated whether risk of infection with SARs-CoV-2 and severe outcomes differed between adults living with and without children.
Methods: Working on behalf of NHS England, we conducted a population-based cohort study using primary care data and pseudonymously-linked hospital and intensive care admissions, and death records, from patients registered in general practices representing 40% of England. Using multivariable Cox regression, we calculated fully-adjusted hazard ratios (HR) of outcomes from 1st February-3rd August 2020 comparing adults living with and without children in the household.
Findings: Among 9,157,814 adults ≤65 years, living with children 0-11 years was not associated with increased risks of recorded SARS-CoV-2 infection, COVID-19 related hospital or ICU admission but was associated with reduced risk of COVID-19 death (HR 0.75, 95%CI 0.62-0.92). Living with children aged 12-18 years was associated with a small increased risk of recorded SARS-CoV-2 infection (HR 1.08, 95%CI 1.03-1.13), but not associated with other COVID-19 outcomes. Living with children of any age was also associated with lower risk of dying from non-COVID-19 causes. Among 2,567,671 adults >65 years there was no association between living with children and outcomes related to SARS-CoV-2. We observed no consistent changes in risk following school closure.
Interpretation: For adults living with children there is no evidence of an increased risk of severe COVID-19 outcomes. These findings have implications for determining the benefit-harm balance of children attending school in the COVID-19 pandemic.
Note: This was prior to variants of concern widely circulating.
Helen H. Suh, Julianne Meehan, Laura Blaisdell, Laurie Browne
Background: Most camps remained closed during Summer 2020, due to concerns regarding child transmission of SARS-CoV-2 and limited information about the effectiveness of non-pharmaceutical interventions (NPIs) within child congregate settings.
Methods: We surveyed US camps about on-site operations, camper and staff demographics, COVID-19 cases amongst campers and staff, and NPI usage as related to pre-camp quarantines, facial coverings, physical distancing, cleaning, and facility modifications. For all NPIs, save quarantines, responses were provided on a 5-point Likert scale format.
Results: Within 486 on-site camps, a range of NPIs were instituted, most often related to reduced camper interactions, staff face coverings, cleaning, and hand hygiene. Camper facial coverings were less common, with campers always wearing masks at ∼34% of the camps. Approximately 15% of camps reported 1+ confirmed COVID-19 case in either campers or staff, with three camps reporting a COVID outbreak. In both single and multi-NPI analyses, the risk of COVID-19 cases was lowest when campers always wore facial coverings. While less effective, constant use of staff facial coverings and targeted physical distancing measures, but not pre-camp quarantine, also reduced COVID-19 risks.
Conclusions: We found constant facial coverings, especially for campers, and targeted physical distancing measures to reduce risks of SARS-CoV-2 transmission within summer camps. Our findings provide valuable guidance for future operations of camp and other child congregate settings with regard to efficient and effective NPI usage to mitigate SARS-CoV-2 infection.
What’s Known on This Subject: Approximately 82% of US overnight camps did not open during Summer 2020 due to concerns regarding children’s ability to transmit SARS-CoV-2. Camps that did operate during this time instituted varied non-pharmaceutical interventions (NPIs) to reduce SARS-CoV-2 transmission, with little information available on the effectiveness of these NPIs within child congregate settings. Large population-based studies are needed to improve our understanding of the extent of SARS-CoV-2 infection amongst children and their caregivers and to determine whether and to what degree child congregate programs can safely open during the pandemic.
What This Study Adds: Our study, the largest survey of COVID-19 cases in child congregate settings at the national level, provides new information on the relative effectiveness of NPIs on mitigating COVID cases among children and staff within camp settings. We showed COVID-19 case rates in campers and staff to be low relative to corresponding case rates in the US and found constant camper facial coverings to be the most effective risk reduction method for SARS-CoV-2 transmission within camps. While less effective, constant use of staff facial coverings and targeted physical distancing measures, but not pre-camp quarantines, were also shown to reduce COVID-19 risks. Our findings has important implications for child congregate settings, helping to guide their successful opening and operation.
Victor Chernozhukov, Hiroyuki Kasahara, & Paul Schrimpf
Abstract: Since the emergence of coronavirus disease 2019 (COVID-19), unprecedented movement restrictions and social distancing measures have been implemented worldwide. The socioeconomic repercussions have fueled calls to lift these measures. In the absence of population-wide restrictions, isolation of infected individuals is key to curtailing transmission. However, the effectiveness of symptom-based isolation in pre- venting a resurgence depends on the extent of presymptomatic and asymptomatic transmission. We evaluate the contribution of presymptomatic and asymptomatic transmission based on recent individual level data regarding
infectiousness prior to symptom onset and the asymptomatic proportion among all infections.
We found that the majority of incidences may be attributable to silent transmission from a combination of the presymptomatic stage and asymptomatic infections. Consequently, even if all symptomatic cases are isolated, a vast outbreak may nonetheless unfold. We further quantified the effect of isolating silent infections in addition to symptomatic cases, finding that over one-third of silent infections must be isolated to suppress a future outbreak below 1% of the population. Our results indicate that symptom-based isolation must be supplemented by rapid contact tracing and testing that identifies asymptomatic and presymptomatic cases, in order to
safely lift current restrictions and minimize the risk of resurgence.
Erik Volz, Swapnil Mishra, Meera Chand, ...., Neil M Ferguson
Abstract: The SARS-CoV-2 lineage B.1.1.7, now designated Variant of Concern 202012/01 (VOC) by Public Health England, originated in the UK in late Summer to early Autumn 2020. We examine epidemiological evidence for this VOC having a transmission advantage from several perspectives. First, whole genome sequence data collected from community-based diagnostic
testing provides an indication of changing prevalence of different genetic variants through time. Phylodynamic modelling additionally indicates that genetic diversity of this lineage has changed in a manner consistent with exponential growth. Second, we find that changes in VOC frequency inferred from genetic data correspond closely to changes inferred by S-gene target failures (SGTF) in community-based diagnostic PCR testing. Third, we examine growth trends in SGTF and non-SGTF case numbers at local area level across England, and show that the VOC has higher transmissibility than non-VOC lineages, even if the VOC has a different latent period or generation time.
Available SGTF data indicate a shift in the age composition of reported cases, with a larger share of under 20 year olds among reported VOC than non-VOC cases. Fourth, we assess the association of VOC frequency with independent estimates of the overall SARS-CoV-2 reproduction number through time. Finally, we fit a semi-mechanistic model directly to local VOC and non-VOC case incidence to estimate the reproduction numbers over time for each. There is a consensus among all analyses that the VOC has a substantial transmission advantage, with the estimated difference in reproduction numbers between VOC and non-VOC ranging between 0.4 and 0.7, and the ratio of reproduction numbers varying between 1.4 and 1.8. We note that these estimates of transmission advantage apply to a period where high levels of social distancing were in place in England; extrapolation to other transmission contexts therefore requires caution.
Office of the Chief Science Advisor of Canada
"Circumstantial evidence on the role of aerosols in COVID-19 transmission is accumulating and some experts have pointed to aerosol transmission as a potentially significant route for SARS-CoV-2 spread. As workplaces and schools reopen this fall, it is important to review the available scientific evidence on airborne SARS-CoV-2, and to assess whether additional measures need to be considered to minimize the transmission of SARSCoV-2 in indoor spaces."
"Experts generally agree that the majority of SARS-CoV-2 transmission occurs through close contact via infected respiratory droplets or aerosols, but that aerosol transmission over longer distances is possible in certain circumstances. The conditions under which long range aerosol transmission of this virus occur, particularly in non-healthcare community settings, are not well understood. A growing number of environmental sampling studies have captured SARS-CoV-2 in air samples, though few studies have detected live, infectious virus in the air."
"Developing science-informed guidance based on available evidence regarding indoor air quality and SARS-CoV-2 bioaerosol transmission demands a collaborative approach that is multidisciplinary and nimble. As further research proceeds and new evidence becomes available that fills knowledge gaps, approaches will adapt."
Children’s Task and Finish Group
Published: 17 December 2020
“Overall, accumulating evidence is consistent with increased transmission occurring amongst school children when schools are open, particularly in children of secondary school age (high confidence): multiple data sources show a reduction in transmission in children following schools closing for half term, and transmission rates increasing again following the post-half term return to school (medium confidence). It is difficult to quantify the size of this effect, and it remains difficult to quantify the level of transmission taking place specifically within schools compared to other settings.”
“Children can transmit within households as well as in educational settings. Previous analysis of ONS data discussed at SAGE 65 indicated that children aged 12-16 were playing a higher role in introducing infection into households than those 17 or over (i.e. being the index case). An update of this analysis with data until 2nd Dec 2020 still supports this, however the increased likelihood has reduced (medium confidence). The difference remains less marked for those under 12 (medium confidence
National Education Union
Published: 12 December 2020
"With increasing infection rates and a new more easily transmitted strain of the virus the NEU is calling for
1. Online learning for the first two weeks of the Spring term except for key workers and vulnerable children to reduce cases amongst students and get testing set up.
2. Directors of Public Health to set up a testing system to be in place that would enable all children to be tested prior to a return to person-to-person teaching.
3. The 2-week period from the 4th of January to be used to begin vaccinating education staff alongside NHS and Care staff. "
"The new variant of the virus will mean that we are all concerned about the best way to see a return to education on the 4th of January.
It was clear at the end of last term that cases were going up sharply amongst primary and secondary children; the ONS Coronavirus Infection Survey suggests that case rates in those two groups were the highest of any of the age demographics. "