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expert reaction to CMOs extending the period of self-isolation to 10 days for people with COVID-19 symptoms or a positive test

Chris Whitty, The Chief Medical Officer (CMO) for England, has announced that the period of self isolation required for anyone with COVID-19 symptoms, or a positive test, is to be increased from 7 to 10 days. 

 

Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician, Liverpool School of Tropical Medicine, said:

“The UK CMOs’ statement today that people with symptoms of Covid-19 or a positive test should self-isolate for 10 days brings the UK into line with guidance from WHO and many other countries, some of whom advocate up to 14 days isolation.

“We are seeing increasing Covid-19 cases in Europe and the UK, where local spikes and outbreaks are leading to reimposition of local lockdown measures.  Therefore, this change of advice from the CMOs, aimed to reduce coronavirus transmission, is particularly timely and welcome.

“However, there will be downsides to the increase in the isolation period.  These include additional loss of income for UK households and difficulties accessing support for day-to-day activities such as shopping for vulnerable people.  It is vital that these are proactively addressed to avoid further hardship.”

 

Prof Rowland Kao, the Sir Timothy O’Shea Professor of Veterinary Epidemiology and Data Science, University of Edinburgh, said:

“With the lifting of restrictions we are experiencing, it is expected that each infected individual will have a greater potential to infect others on average, as the reduction in restrictions implies the opportunity for greater contact.  And this means that the absolute potential per transmission in the period from 7 to 10 days after a positive test (or symptoms occur) is also greater than it would have been during lockdown.  This is therefore a sensible precautionary measure to reduce the risk from potentially infected individuals in order to prevent more generalised restrictions from being necessary.  Of course the impact of this extended isolation period on individuals must also be considered, and appropriate measures put in place to make sure they are supported, especially for those more vulnerable members of society.”

 

Dr Julian Tang, Honorary Associate Professor in Respiratory Sciences, University of Leicester, said:

“The evidence for this 10-day rather than 7-day cut-off has been around for some months already – and more and more studies confirm this.

“See this 17 June 2020 WHO Scientific Brief that explains this equivalent discharge criteria and lists references 8-11 cited to support this 10-day cut-off: https://www.who.int/news-room/commentaries/detail/criteria-for-releasing-covid-19-patients-from-isolation  Essentially these 4 studies (references 8-11 in the above WHO document) demonstrate that no viable virus can be detected after day 10 post-symptom onset in most acute symptomatic/ asymptomatic COVID-19 infections – despite the persistence of SARS-CoV-2 PCR positivity well beyond this period.  Hence the safe discharge from isolation after day 10 post-illness onset.

“There have been concerns about the former 7-day isolation cut-off for sometime now – because it just didn’t tally with the evidence.  Finally, now it does.”

 

Prof Peter Openshaw, British Society for Immunology spokesperson, and Professor of Experimental Medicine at Imperial College London, said:

“With a sustained decline in total infection rates, keeping the coronavirus infection rate low is now a top priority.  Given some hints of resurgence, today’s news that the period of isolation following symptom onset is to increase from seven to ten days is to be welcomed.  Our knowledge of SARS-CoV-2 infection is increasing all the time.  We now know that people with COVID-19 seem to be most infectious (i.e. most likely to spread the disease to other people) at about the time of symptom onset.  However, recent studies have found that there are cases where infectious virus can still be recovered from respiratory secretions up to 9 days after symptom onset.  This, in theory, means that such people may be capable of transmitting the virus.  What needs to be determined is just how much transmission actually occurs in these later stages of illness.  It’s clear that some people have virus RNA (its genetic material) detectable for a month or more after illness onset, but once the immune system starts to make antibody the infectivity declines rapidly.

“We are now in a critical stage of controlling the disease.  Keeping infection rates low is vital and extending the period of isolation to 10 days brings us in line with some other European countries.  It seems to be a sensible precaution to keep pressure on the virus while other measures to control the spread of SARS-CoV-2 are developed.”

 

Prof Paul Hunter, Professor in Medicine, UEA, said:

“One of the big problems with determining how long people should self-isolate after developing symptoms that are consistent with COVID-19 is that PCR tests on nose and throat swabs can remain positive for several weeks after onset of symptoms.  However, this does not mean that people will remain infectious for that period.  Indeed we know that in many cases where people are PCR positive it is not possible to culture the virus from those samples and so it is reasonable to assume they are not infectious.

“One as yet un-peer reviewed study of hospitalised patients by van Kampen and colleagues, ‘Shedding of infectious virus in hospitalized patients with coronavirus disease-2019 (COVID-19): duration and key determinants’ (https://www.medrxiv.org/content/10.1101/2020.06.08.20125310v1.full.pdf) reported that “The median time of infectious virus shedding was 8 days post onset of symptoms (IQR5 –11, range 0 –20)” and that the probability of isolating infectious SARS-CoV-2 was less than 5% when the duration of symptoms was 15.2 days (95% CI 13.4 –17.2) or more.

“The World Health Organization guidance is dependent on whether or not people are symptomatic https://www.who.int/publications/i/item/clinical-management-of-covid-19.  The WHO guidance says that for people who are clinically symptomatic then they should be isolated for at 10 days PLUS at least three days 3 days without symptoms.  So If somebody is ill then recovers after 4 days, the WHO say they can be released from isolation at day 10.  If they are ill for three weeks, the WHO says they can be released after 21+3=24 days.  And the WHO says people who asymptomatic but test positive can be released after 10 days unless they become symptomatic when the above applies.

“In the light of these observations the previous UK isolation period of 7 days was too short and the news that UK advice has now been brought in line with WHO advice is to be welcomed.”

 

Dr Shaun Fitzgerald FREng, Royal Academy of Engineering Visiting Professor at the University of Cambridge, said:

“This change is important.  Given that there is now stronger evidence which shows a real possibility of infectiousness between 7 and 9 days after illness onset, 10 days isolation seems very sensible.  With ~600 new cases per day at the moment, this is effectively an extra 1800 person days of isolation each day.  However, the benefits could be large in terms of our efforts to keep the transmission numbers down.”

 

 

https://www.gov.uk/government/news/statement-from-the-uk-chief-medical-officers-on-extension-of-self-isolation-period-30-july-2020

 

All our previous output on this subject can be seen at this weblink:

www.sciencemediacentre.org/tag/covid-19

 

Declared interests

None received.

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