Pre-symptomatic covid-19 cases (FOI)

Request

It is well known that a number of Covid-19 cases are pre-symptomatic cases, ie they appear as Asymptomatic (not showing any symptoms) at the point of test, but develop symptoms anywhere between one to five days later.

A

Do pre-symptomatic cases get counted as asymptomatic when tested positive and showing no symptoms?

B

Are they later recounted as symptomatic if symptoms develop later? If not, do they remain in the asymptomatic figures?

C

Are there any statistics kept for the proportion of apparently asymptomatic cases (on testing) who later turn out to be symptomatic (either with further testing or reported symptoms)?

D

Is there any later contact with asymptomatic cases after 14 days to see if they were in fact pre-symptomatic?

Background: A study in a nursing home showed when two cases were identified, all staff and residents at the facility were tested for the virus, and 27 additional people tested positive. Among those people, 18 who tested positive for the new coronavirus were not experiencing symptoms of Covid-19 at the time of testing, including 14 residents of the facility. However, the report noted that eight of those 14 residents were later classified as pre-symptomatic, because they developed symptoms of Covid-19 within one to five days after testing.

Response

A

Yes; ‘asymptomatic’ means that the individual does not have symptoms

B

As part of our monitoring of active cases we would reclassify them from asymptomatic to symptomatic – this affects how / when we then count them as recovered.

C

If a person is asymptomatic when they test positive but they subsequently develop symptoms, then their symptomatic status is changed to “yes”. Data is collected about the numbers of people who report they are ‘well’ and those who report symptoms in the daily SMS, including those who initially report being ‘well’ and subsequently report symptoms.

D

Asymptomatic persons become ‘recovered’ after 14 days isolation, and our contact with them ceases.