Updated on May 15th, 2020
All medical investigations involve a cost benefit analysis. This is not only financial cost. It is well recognized that excessive medical investigations have the potential to increase not only anxiety but also create complications and illness from subsequent tests and procedures. However, testing is a key component of the strategy for controlling the COVID-19 epidemic. As always information is key to resolving this dilemma.
Tests which may be performed for COVID-19 can be divided as follows:
- Tests which specifically look for the virus.
- Tests on the blood that look for evidence of antibodies which suggest current (IGM) or previous (IGG) infection.
There are several tests available which check for the COVID-19 virus. In a community setting these tests are now being performed at home. Hong Kong has increased the capacity for testing and is now actively encouraging more widespread testing. Newer and more sensitive tests are now available and it remains likely that testing for presence of the virus will remain a key component of epidemic control. It is likely that when borders open, testing before travel will be required.
There is also a blood test which measures antibodies against COVID-19 IGG. The IGG test becomes positive within the first few weeks of the illness. It is technically more difficult to produce antibody tests than PCR tests and there is still not international agreement about which available tests are the most accurate. OT&P are currently involved in a study with Hong Kong University looking at the evidence for the frequency of positive antibodies in our population. It will take a bit longer before we have a greater understanding of the role of the blood tests in early diagnosis.
The incidence of infection in Hong Kong is very low. Even in countries with widespread infection the antibody studies suggest antibody levels which are below those needed for herd immunity. We also do not understand how many infected people get antibodies, how effective they are in protection and how long they are likely to last. For this reason the concept of an antibody test as an ‘immunity passport’ is still some way off. It is likely that PCR testing will be the mainstay of control for some time yet.
We are aware that there is an increasing discussion about COVID-19 testing and we fully expect that our patients wish to make informed decisions on matters regarding their health. We are able perform testing both for the virus and for antibodies. Before considering testing it should be recognized that:
- The majority of patients contracting COVID-19 have a relatively mild illness and make a full recovery.
- If a PCR test is positive, the doctor will have an obligation to inform the Department of Health, and you will be admitted to hospital for quarantine and any close contacts may be asked to quarantined in a government facility.
- There are no mandatory reporting obligations regarding a COVID-19 IGG test. That is to say your doctor will not inform the health department. Clearly there are public health implications and you should discuss any positive test with a medical professional to decide the implications in context.
- PCR tests are point in time tests. A negative today does not guarantee that you will not become infected or develop symptoms in the future.
- The incidence of COVID-19 remains low in our population. Whilst that may change currently it is statistically most likely that in low risk cases symptoms are likely to be caused by another form of infection.
Hong Kong has instituted a policy of testing, case identification and quarantine. Hong Kong has world class systems and expertise in the management of infectious disease. This has been reflected in the number of COVID-19 cases in comparison to other countries which were hit later by the epidemic. All OT&P clinics have been fully operational throughout this process. We are supporting the Hong Kong public health strategy and have been working closely with the Department of Health. Including PCR and serology we have performed more than 2200 tests for COVID-19 with the vast majority being negative. We have enhanced infection control procedures in compliance with CHP recommendations and our ongoing accreditation with ACHS. We will continue to care for all our patients.
If you have any concerns or specific questions regarding this issue or if you wish to discuss the implications or logistics of testing for COVID-19, please arrange an appointment to discuss with your doctor.
1. Harris, R. (2020, February 28). How A Coronavirus Blood Test Could Solve Some Medical Mysteries. Retrieved from https://www.npr.org/sections/health-shots/2020/02/28/810131079/how-a-coronavirus-blood-test-could-solve-some-medical-mysteries