NERVTAG is the New and Emerging Respiratory Virus Threats Advisory Group, reporting to PHE (Public Health England).
It began a series of extraordinary meetings on the coronavirus from 13th January 2020 (normally it meets once per year), summarized in Table 1.
In January, it agreed with PHE that the risk to the UK population was ‘very low’, rising to ‘low’ (by this stage, the rate of human-to-human infection was unclear). It focused primarily on (a) developments in the city of Wuhan (population: 11m) and then other parts of China, and (b) advice to UK travellers to China, then (c) giving advice for the NHS on how to define a case of COVID-19 in relation to symptoms (primarily fever) and a history of travel to an affected area. From the end of January, it began to discuss personal protective equipment (PPE) frequently, without describing the need to modify PHE advice significantly (and was not responsible for securing supply).
In February, it agreed (on the 21st) that the risk to the UK population was ‘moderate’. It responded to questions from COBR (Cabinet Office civil contingencies committee, convened to discuss national emergencies) on the most effective public preventive efforts, prioritizing frequent and effective hand washing and advising against face masks for members of the public with no symptoms. In response to questions from the Department of Health and Social Care (DHSC), it described a ‘Reasonable Worst Case’ in the UK (to inform scenario modelling) as an 85% infection of the population, with half of those affected showing symptoms, then suggested that an estimate of 4% (of those with symptoms) needing hospital care ‘seems low’, while 25% (of the 4%) requiring respiratory support ‘seems high’.
In March, it advised that voluntary self-isolation should be 7-14 days after ‘illness onset’, depending ‘on desired balance between containment and social disruption at the particular stage of the epidemic’. It should be longer during the ‘containment’ phase (‘In the current situation NERVTAG would prefer this period to be towards the longer end of the range’) but could be shorter when transmission is so widespread that someone infected represents a decreasing share of the infected population (‘an increased proportion of people may still be infectious when they end self-isolation but they will constitute a decreasing proportion of all infectious people’, 6.3.20: 2).
Throughout, members of NERVTAG focused quite heavily on what seemed feasible to suggest, informing initial thoughts on:
- Handwashing advice. Initially it warned against too nuanced messages to the public, such as on the amount of time to wash.
- Face mask use. It identified (in multiple discussions) the unclear benefits if someone is well, plus the unlikely widespread public compliance, coupled with limited public training in their hygienic use and disposal (and the possibility that mask use in the UK ‘may add to fear and anxiety’ – 28.1.20: 8)
- Voluntary self-isolation. It expressed uncertainty about public compliance, and the difficulty of knowing when the illness begins and infectiousness ends.
- Port of entry screening, assuming a low impact since it would miss most cases.
[Note: please use the PDF if the tables look a bit weird below]