With a near endless stream of information regarding COVID-19 appearing daily, we spoke with RCPA Fellow, Dr Rohan Beresford to gain a better understanding of some of the current topics being discussed in the media. Dr Beresford is a Microbiologist and Infectious Disease specialist working at Concord Hospital.

What is a cytokine storm?

Cytokines are chemicals which are released by the immune system in response to infection. These chemicals have a specific effect on the interactions and communications between cells, signalling when to ramp up an inflammatory response and when to take it back down again.

During a cytokine storm, there is an excessive level of cytokines released in the body which can be very damaging. In a lot of the severe cases of COVID-19, we find that some of the chemicals associated with cytokine release and inflammation, such as interleukin 6, C-reactive protein (CRP) and ferritin, are quite high. This suggests that people who go on to develop a severe or critical version of COVID-19 have a very prominent immune response. This means that the problem could therefore be an inflammatory problem rather than direct infection.

There are trials underway at the moment to look at whether dampening down the immune system in this cytokine release may improve outcomes.

Why is COVID-19 affecting some people differently to others?

Some of the reasons people react badly to COVID-19 make sense, however some do not. For example, it is not particularly surprising that some people with underlying health conditions are more affected. Those who have underlying lung disease, obesity or heart disease are all people that you would expect to do worse with infection. We are also seeing a large mortality rate in the elderly population which isn’t too different to what we see with a lot of other viral infections, such as with influenza.

There are a couple of surprises that have come out of this pandemic. Firstly, there has been a lot of media discussion about young people, particularly children not being infected as readily or as severely. This is quite unusual as we usually see viral infections affecting very young children relatively strongly. Secondly, pregnant women, who were hit very hard with swine flu, don’t seem to be abnormally affected compared to the general population.

There have been some theories circulating about why some countries are worse affected than others, but it is still very difficult to know. It could be genetic, especially in those cases of a cytokine storm, or it could be how the outbreak is spreading in different populations.

What is herd immunity?

Imagine that you are infected, and you walk into a room full of people with no immunity. When you cough, a number of people in that room will become infected. Now, if some people in that room are already immune, then less people will become infected if you walk in and cough. This forms the basis of herd immunity and can be exploited over time to slow or stop the rate of infection. If one person infects less than one person on average, then the disease will die out over time.

When we discuss herd immunity, we are usually referring to a vaccine rather through native immunity. This has proved very useful in the past with vaccinations such as chicken pox and measles. It is important to recognise that whilst native immunity can provide herd immunity over time, it will most likely come at a human cost. In the UK for example, they were looking at over half a million deaths to achieve herd immunity for COVID-19.

A 60-70% infection rate is required in order to reach herd immunity for COVID-19. What people sometimes fail to realise, is that this applies to the general population and includes achieving a 60% immunity in the elderly population. When you consider the mortality rate for people over 80 is 15%, then achieving herd immunity is going to result in a lot of deaths. Herd immunity is therefore much better coming from a vaccination program. Australia’s approach of clamping down on the number of infections has been the much better strategy.

Are there any treatments to treat coronavirus at the moment?

As it stands, there are no known therapies that are effective at either preventing or treating coronavirus. There are a number of drugs which are being trailed in this space, however none have been shown to be effective. We are also still learning the consequences of this virus on different people.

Therapies currently being considered include lopinavir/ritonavir which is an old HIV treatment. Whilst it was not effective in its original trial in severe COVID-19 patients, there are trials to see if it can be used to prevent people becoming severely unwell. Hydroxychloroquine has also become widely talked about due to some promising early data, however there were a lot of problems with how that data was collected and subsequent trials haven’t shown the same benefit. There is also a drug which was previously looked at for Ebola and SARS-1 but unfortunately has not yet been shown to be effective in trials for COVID-19. I believe there are further trials with this drug which are ongoing.

In Australia, there are currently trials underway to see whether some of these drugs would work on our population but at the moment, there is no proven therapy for COVID-19. All therapies that we’re advocating at the moment should only be used as part of a trial.

What is the second wave of infection?

Many countries have seen their cases rapidly increase and then plateau or fall following the introduction of public health measures. The concern is that when we release social distancing measures, we might see a second, or even a third peak of infection. This is because only a very small number of our population has been infected, therefore most of us are not immune.

We could still be at least 12-18 months away from a safe vaccine, if at all, therefore we could see multiple recurring peaks when we try to relax measures. One of the main challenges we face now is to release things in a way that allows COVID-19 to stay supressed, but not to move from one public health intervention to complete relaxation, and then to reintroduce the same measures again.

Can we keep up with an increase in demand for testing in Australia?

Australia has been in a very good place with testing. We saw a very rapid increase in testing very early and we are ahead of many other countries in terms of the percentage of our population being tested.

At the moment we are able to keep up with an increase in testing but there is a lot of demand across the globe for the different parts required for testing. This a very fluid area and the Federal Government is involved to try and ensure we have adequate supplies for testing. I believe that keeping up our high level of testing is going to be crucial in bringing the pandemic under control.