COVID-19: 10 DAYS, 7 DAYS, OR 5 DAYS SELF-ISOLATION. WHAT'S WISE?

We have a problem.  As forecast, the high rate of COVID infection means a high proportion of the workforce is off ill, and otherwise having to self-isolate.  That is adversely impacting many organisations, which are having to close or reduce services.  NHS and trains, and potentially food supply.  Getting people back to work is a critical objective.

Reducing the self-isolation period would help to get people back to work, if that is medically prudent.

In England, the self-isolation period has already been reduced to 7 days, provided certain conditions have been met.  Now 5 days is being considered, as is happening in other countries such as the USA.  

Is 5 days wise?  Let's investigate.

THE OMICRON DIFFERENCE

We now know that Omicron infects cells through a different mechanism to earlier variants.  That lets Omicron spread more quickly, both between people and within a person.   Plus different symptoms.  Generally more moderate disease, but potentially serious enough for some people to require hospital treatment, just like flu.

We're effectively got a different disease, that I'm calling COVID-21.  The 'cousin' of COVID-19, with family similarities such as PCR and LFT tests for earlier variants also working for Omicron.  

But differences that make dealing with it a different proposition. As Omicron has become the dominant variant, we need a self-isolation strategy that focuses on Omicron, but doesn't forget Delta and earlier variants.  And also is well prepared for sons of Delta and Omicron, and indeed any other new Variants of Concern.

 WHAT DO WE KNOW ABOUT DELTA INFECTION?

The speed with which early variants up to Delta spread within a person depends upon each individual.  But is broadly like this, where:

• It takes around 3 days after infection to be LFT positive 
• It takes around 8 days to then become LFT negative, but could be infectious longer.  Hence the original 10-day self-isolation period
  

The American CDC (Centers for Disease Control and Prevention) confirms that of being infectious "the majority of  transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after".

HOW IS OMICRON DIFFERENT?

My own experience, supported by experience of other people, suggests timescales are shortened with Omicron:

• LFT positive in only around 24 hours
  
• LFT negative as early as on day 4
  

SO HOW CAN WE CATER FOR BOTH DELTA AND OMICRON?

In shortening the self-isolation period from 10 days to 7 days, there are two important conditions:

• Two consecutive negative LFTs on days 6 and 7, at least 24 hours apart
• No symptoms such as a raised temperature

Otherwise self-isolation should continue.  That's appropriate for Delta, and in many cases the full 10 days would be required.

But do we really need 7 days for Omicron?  Provided those two conditions are fulfilled, with negative LFTs moved to days 4 and 5, it appears 'safe' (low risk) for people to exit self-isolation on day 5.  

With it being important for people to get back to work if they have recovered from Omicron, then a change to day 5 is an important improvement.

WHAT ARE THE MODELERS SAYING?

Professor John Edmunds, a member of Sage and an epidemiologist at the London School of Hygiene and Tropical Medicine, has just released experimental modeling results.  

As expected, this has confirmed that a 'test to release' scheme at 5 days produces no difference in the number of infectious days in the community from covid-positive cases than at 7 days.  

Provided each person has negative LFTs in the last two days.

 

 

WHAT ABOUT THE APPROACH IN USA?

The 5-day rules are somewhat different:

• "Isolate for 5 days and if [you] are asymptomatic or [your] symptoms are resolving (without fever for 24 hours)" - but otherwise continue self-isolating
  
• "Follow that by 5 days of wearing a mask when around others to minimize the risk of infecting people they encounter."

The requirement to wear a mask stops after 10 days.

The CDC has also adjusted the need for contacts to self-isolate, reflecting that masks are primarily to provide protection to other people, not so much the wearer:

• "Individuals who have received their booster shot do not need to quarantine following an exposure, but should wear a mask for 10 days after the exposure.  For all those exposed, best practice would also include a test for SARS-CoV-2 at day 5 after exposure. If symptoms occur, individuals should immediately quarantine until a negative test confirms symptoms are not attributable to COVID-19"
• "For people who are unvaccinated or are more than six months out from their second mRNA dose (or more than 2 months after the J&J vaccine) and not yet boosted, CDC now recommends quarantine for 5 days followed by strict mask use for an additional 5 days. Alternatively, if a 5-day quarantine is not feasible, it is imperative that an exposed person wear a well-fitting mask at all times when around others for 10 days after exposure."

 The UK approach is somewhat better:

• Adding the need for negative LFTs on two consecutive days
• An ongoing need to wear masks, in case get re-infected, and to reduce risk of being re-infected.  Bear in mind that Omicron can be caught by people who have immunity to Delta and earlier variants

IN CONCLUSION

We need an approach to ending self-isolation as early as possible that caters for all types of variants, especially Delta and Omicron:

• To let people get back to work, be they employed, self-employed on or zero hours contracts
• To let parents and carers get back to what they need to do
•  To reduce the strain on organisations struggling to stay open and provide a near-normal service.  That is especially relevant to the NHS and the food supply chain
  

With Omicron being the dominant variant now, with infection timescales shorter than Delta, it seems both reasonable and advantageous to reduce self-isolation to 5 days.  Provided the LFT and other conditions are met, which will cater for Delta and other variants.

The challenge is to ensure people are aware of the conditions, and not think 5 days is automatic.

Then to reduce risk of re-infection and passing it on, it's best to continue with basic precautions such as mask wearing beyond ending isolation, and indeed past ten days.

UPDATE 13 JANUARY 2022:  Sajid Javid has now announced a reduction to 5 days.  But is it?