Coronavirus links and resources
(Pathology updates below)

Pathology updates

COVID-19 serology  (updated 16/07/2020)

Serological testing for COVID-19 is a rapidly evolving area of testing.

SNP has now commenced offering serology testing for COVID-19 infections. 

Please note State public health authorities require all requests for COVID-19 serological testing and all results to be notifiable.

 

Is serology better than PCR?
No. The primary test for diagnosing acute infection will continue to be PCR of respiratory samples.

What does a positive serology test mean?
At this moment, serological testing will consist of an IgG result only. Current testing for IgG has a sensitivity of approximately 94%, and specificity of >98%.
Positive serology may help to provide evidence of exposure to COVID-19 in the absence of a positive PCR. IgG seems to be first detectable around 10-14 days following infection. However, it can take up to four weeks following infection with COVID-19 for an antibody response to be detected in some individuals.

If my patient has a positive serology test are they immune?
It is unknown at this stage if humans can or will develop long-term immunity to COVID-19. The presence of IgG antibodies only indicates the person has been infected with the virus at some stage (likely >10 days ago).

If my patient has a positive serology test does that mean they are no longer infectious?
The presence of antibodies to COVID-19 gives no direct indication of whether a patient is infectious or not. The decision to clear a positive patient from isolation depends on the combination of clinical course, exposure history, time since diagnosis, and clinical judgment

Why can’t I see an IgM result? Isn’t that more useful than IgG?
Extensive analysis of multiple serological kits currently available has shown IgM detection for COVID19 is significantly less sensitive and less specific that IgG. As serology currently should not be used to diagnose acute infection, IgG has been selected as the test likely to give the most definitive answer regarding possible past COVID-19 exposure.
Current testing for IgG has a sensitivity of approximately 94%, and specificity of >98%.

Notification process of COVID-19 results  (updated 20/05/2020)

All positive COVID-19 results will be phoned by the microbiologists to the referring doctor. Simultaneously, results will be notified electronically to the relevant public health department.

It is the referrer’s responsibility to follow-up on patient results.

20/05/2020 - All results are reported to the referring doctor and negative results are sent directly by SMS to those patients who have provided their mobile phone number.

Clearance testing for COVID-19

Recommendations for clearing COVID-19 patients from isolation does vary from state to state. Please check the guidelines appropriate to your area. Links can be found on our 'Links and resources' page.

In general, it is possible for patients to have a positive PCR test (or an intermittent positive PCR test) for at least three weeks following infection. The detection of residual RNA does not necessarily mean that the patient is still infectious.

Currently, most guidelines restrict clearance testing to specific high-risk indications and use clinical criteria (e.g >10 days since onset and >72 hours symptom-free) to allow patients to cease isolation.

COVID-19 specimen collection options

  • Doctor or health care practitioner collect
  • SNP respiratory testing centre
  • Public hospital fever clinic
  • SNP's mobile collection service. For more information on this service including patient criteria please contact our Patient Services support team on (07) 3377 8747.

Point-of-care Tests for COVID-19 – what’s the problem?

Point-of-care (POC) test kits are available in Australia for COVID-19 testing, but currently should not be used for acute diagnosis of COVID-19.

In some states (e.g. WA) it is illegal to use a point-of-care test for acute diagnosis. POC tests are performed on a fingerprick sample and measure antibodies. They do not directly detect virus.

Currently, the TGA has strictly limited their use as the tests do not have sufficient sensitivity or specificity to reliably rule in or out COVID-19 infection for an individual.

Formal evaluation of some POC kits by the Doherty Institute in Melbourne has confirmed these concerns. A Royal College of Pathologists position statement has further detail on point-of-care testing and can be viewed here.

 

COVID-19 and children

Children are rarely severely affected by the virus, particularly children <10 years old, and even babies. The reason why this is the case remain unclear.

It is unclear if children with underlying chronic medical conditions (e.g. diabetes, malignancy, asthma) are at risk of any increase in severity. Reports of severely affected children from countries where the disease has been widespread (e.g. Italy, Spain, UK, USA) are still rare.

Children usually acquire infection from infected adults who have been in close contact with them (e.g. in households)

Child-to-child or child-to-adult transmission is uncommon.

Investigations of outbreaks in schools have not uncovered large groups of infected, asymptomatic children, as was originally feared.

There have been several reports in recent weeks of children with a Kawasaki Syndrome-like illness presenting to hospitals in countries where COVID-19 has been widely circulating in the community. These include Spain, Italy, France, UK, and New York (USA). None have been reported in Australia to date.

Currently, this illness has not been proven to be directly caused by COVID-19, but there is concern it may represent a rare post-infectious phenomenon. The WHO have released a case definition (link: https://www.who.int/publications-detail/multisystem-inflammatory-syndrome-in-children-and-adolescents-with-covid-19 ) to aid in identifying further cases.

Children are generally older than those seen with Kawasaki Syndrome (usually < 5 years), present acutely with high fever, high inflammatory markers, rash, conjunctivitis, abdominal pain, mucosal changes and swelling and maybe severely unwell.

Exclusion and empiric treatment of more common causes of such a presentation (such as Toxic Shock from Streptococcus pyogenes or Staphylococcus aureus, or sepsis) is vital.

Treatment of PIMS-TS  currently is similar to Kawasaki Syndrome, with IVIG, prompt supportive care, and other immunomodulatory agents.