JOHN DWYER. Questions we need answered before we can safely ease COVID-19 restrictions.

Apr 20, 2020

COVID decisions at the cross roads; which path will Australia take?

Australian’s commitment to social distancing has reduced the spread of COVID-19, saving lives and sparing our hospitals from the impossible-to-manage pressures experienced in Europe and the USA. As in many countries, economic miseries are pressuring governments to plan the easing of restrictions. Responding to such pressuring, a number of countries are providing ‘aspirational’ dates which are all too often unrealistic while in the US we see a President supporting the rights of people to gather in large crowds to rebel against critically important and legally required social distancing mandates.

We now have evidence from a number of countries including Singapore, Japan and even China, that premature easing can see a rapid resurgence of cases. Australians need to accept the evidence-based imperative to continue social distancing while ‘real world, real time’ research provides us with the data required for a staged and safe journey to the new normality shaped by our COVID-19 experience. There is so much that we still don’t know, but must find out.

That information and the tactics derived therefrom must be framed around the possibility that we might never have a cure nor a vaccine. We all hope that is not the case but, to date, we have never found an effective medication to combat any corona virus infection nor made a vaccine which prevents them. We do, however, have good reasons to consider that we can control the spread. While it is not likely, eradicating the virus is not impossible. Neither control nor eradication is achievable without our actions being empowered by answers to crucial questions that can only be acquired by extensive testing of our population on a scale never before attempted.

Our immediate focus must be on acquiring the needed testing capacity. This presents two challenges; obtaining and administering. To date, we have severely rationed testing because of a world-wide shortage of the needed reagents. We are promised that much broader testing will soon be available and a start has been made with all people with any respiratory symptoms being urged to get a COVID test. We need to now move rapidly to further broaden testing to address the reality that COVID-19 can readily be spread by infected individuals without symptoms.Testing technology is improving rapidly making testing easier and more accurate. Our testing regimens need to be massively resourced and rapidly upscaled.

Testing allows us to determine who is infected and infectious and examine an individual’s immune response to the infection. We need to resource ‘second generation’ tests for the presence of COVID-19 which provide a result in five minutes – ‘point of contact’ tests. The new rapid tests (for viral RNA) can be done with respiratory secretions or finger-prick blood. We should explore the possibility of individuals collecting their own samples and taking them for testing. A number of countries are planning to use this faster, safer and more efficient method.

‘First generation’ tests for antibodies are now available. Some of the marketed assays were found to give inaccurate results so we are validating in our own laboratories assays to be used in Australia. These require a blood sample and provide rapid results using technology that resembles the rapid test for pregnancy. To answer many of the most important questions, we need to test individuals for both the presence of virus and antibodies.

Here are some of the major questions these tests will allow us to address? As many countries are exploring the same questions, the sharing of information will be crucial.

What is the prevalence in our communities of the symptomless spreaders of the virus?

How long are they infectious?

Do they develop antibodies for long-term protection?

How many non-tested individuals, with relatively mild symptoms, have COVID-19?

Can we ease quarantining for new arrivals in our island country by testing for virus and antibodies?

Is there evidence that some infected Australians, with no history of infection, now have antibodies to prevent further infection (the beginning of ‘herd immunity’).

What is the antibody status of the thousands of recovered Australians?

Can we follow them to look for antibodies?

At what stage of infection do antibodies first appear.?

We know that infected people produce antibodies, but are they the protective, ‘neutralising’ antibodies?

It’s important that we understand the advantages and limitations of antibody testing.There is no such thing as an ‘antibody’ to a virus as such. Antibodies react to small clusters of the virus’s ‘foreign’ amino acids. The shape of the antibodies enables them to bind (key in lock fashion) to the shape possessed by this small grouping of foreign amino acids. Our immune system will, therefore, produce many antibodies (immunoglobulins) to different sections of the virus. To stop the virus from entering a cell in our respiratory tract we must have, among those antibodies, ones which binds to the virus’s ‘hook’ which lock onto the surface of an attacked cell and blocks the virus’s tiny structure which punctures the cell. These ‘neutralising antibodies’ belong to the ‘IgG’ (Immunoglobulin G) antibody class.

We need to know if IgG anti-COVID antibodies can protect from COVID-19 and for how long. This question is being actively pursued. It will provide crucial evidence about the likelihood of producing an effective vaccine. Preliminary data suggest that blood from recovered people contains antibodies which could help patients with severe COVID infection. Some studies from China, however, suggest that antibody production is variable. We know from other corona virus epidemics that infection with these viruses sometimes induces long-lasting immunity and sometimes doesn’t.

The data collection required will be expensive, though hardly daunting when we are spending $130 billion to protect Australians from the inevitable economic contraction. The scope of the testing will involve great logistical demands and take a number of months to provide answers. It is our great challenge but success could provide lifesaving rewards.No country has a better chance for containing this epidemic, but containment requires a partnership between an informed community embracing social distancing, health authorities managing contact tracing and researchers supplying us with the needed data which will determine how we can conquer this enemy.

Professor John Dwyer. Immunologist and Emeritus professor of Medicine NSW.

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