Coronavirus, well people spreading infection

I think the CDC have changed their testing guidelines in order to prevent the virus being spread by people with a negative test result. This is because people who test negative could go on to test positive in the next few days. This is important as people are most infectious in the day or two immediately before and after the onset of symptoms.

Proportion of asymptomatic coronavirus disease 2019: A systematic review and meta‐analysis (Journal of Medical Virology, 21 July)

Meta Analysis

N = 50, 155

41 studies

Asymptomatic, confirmed COVID‐19

Overall pooled data

15.6% are asymptomatic

84.4 are symptomatic

Asymptomatics in children

N = 1, 152

11 studies

27.7% asymptomatic

72.3 symptomatic

Nearly half of the patients with no symptoms at detection time will develop symptoms later

48.9% of asymptomatic go on to become symptomatic

Asymptomatic COVID‐19 patients could have abnormal laboratory and radiational manifestations

Which can be used as screening strategies to identify asymptomatic infection.

CT results in asymptomatics

N = 36

4 studies

63% had an abnormal CT

Reduced white blood cell count, 27%

Increases lymphocyte count

Increased lactate dehydrogenase, 42.3%

Increased C‐reactive protein, 11.5%

Clinical Course and Molecular Viral Shedding Among Asymptomatic and Symptomatic Patients With SARS-CoV-2 Infection in a Community Treatment Center in the Republic of Korea

Aim

To quantitatively describe SARS-CoV-2 molecular viral shedding in asymptomatic and symptomatic patients

Method

Cohort study

n = 303

Isolated in a community treatment center in Korea

Results

110 (36.3%) were asymptomatic at the time of isolation

21 of these (19.1%) developed symptoms during isolation

Time from detection of SARS-CoV-2 to symptom onset in presymptomatic patients was 15 (13-20) days

Time from diagnosis to the first negative conversion

Asymptomatic, 17 days

Symptomatic, 19.5 days

Viral loads, same

Meaning

Many individuals with SARS-CoV-2 infection remained asymptomatic for a prolonged period

Viral load was similar to that in symptomatic patients

Isolation of infected persons should be performed regardless of symptoms

Temporal dynamics in viral shedding and transmissibility of COVID-19 (Nature medicine, 17th August)

94 patients with laboratory-confirmed COVID-19

Estimated that 44% of secondary cases were infected during the index cases’ presymptomatic stage

Disease control measures should be adjusted to account for probable substantial presymptomatic transmission.

The implications of silent transmission for the control of COVID-19 outbreaks (PNAS – US, 28th July)

If 17.9% of infections are asymptomatic

Presymptomatic transmission, 48% of transmission

Asymptomatic transmission, 3.4% of transmission

Even immediate isolation of all symptomatic cases is insufficient to achieve control

Urgent need to scale up testing of suspected cases

Supplemented by rapid contact-based surveillance to identify exposed individuals

prior to their infectious period

Overview of Testing for SARS-CoV-2 (COVID-19)

Considerations for COVID-19 Diagnostic (Molecular or Antigen) Testing

Mild symptoms of COVID-19

Your health care provider may advise a test.

If you test positive or do not get tested, self-isolate for at least 10 days after symptom onset

And at least 24 hours after the resolution of any fever (without the use of fever-reducing medications)

If you have been in close contact (within 6 feet) of a person with a COVID-19 infection for at least 15 minutes but do not have symptoms

You do not necessarily need a test, unless in a vulnerable group

Or

Health care provider or State or local public health officials recommend you take one

A negative test does not mean you will not develop an infection from the close contact or contract an infection at a later time

You should monitor yourself for symptoms

If you do not have COVID-19 symptoms and have not been in close contact with someone known to have a COVID-19 infection:

You do not need a test.

If you are in a high COVID-19 transmission area and have attended a public or private gathering of more than 10 people (without widespread mask wearing or physical distancing)

You do not necessarily need a test

Live or work in a care facility

You will need to be tested

Critical infrastructure worker, health care worker, or first responder

You may need to get a test, according to your employer’s guidelines.

C.D.C. Now Says People Without Covid-19 Symptoms Do Not Need Testing