alicespringstomind

The Role of Public Health

I’ve worked in public health for 20 years and hold public health qualifications which influence my practice on a daily basis.  I understand that SARS-CoV-2 has entered the human transmission chain and is causing a global pandemic.  I understand that a public health response has to be mounted and that for now, without adequate medical measures, non-pharmaceutical interventions are required.  I don’t want to see anyone lose their life to Coronavirus and I fully support the implementation of an adequate, evidence-based public health response.

That said, I consider all premature and preventable death to be of equal concern. The world today is experiencing exponential excess loss of life due directly to inappropriately drastic measures.  I hold public health in high regard as an evidence based discipline whose role is to educate people, prevent disease and promote health.  Public health also monitors disease patterns and counts disease and death rates, with a realistic acceptance that people are always going to transmit diseases between each other and die from preventable things, for a range of complex reasons, despite decent public health interventions.

Part of the public health role is to inform whilst minimising undue fear and anxiety.  In my experience this has always competed against a fervent media, from local rags to national and international corporations.  This is in part because fear and outrage are highly profitable but, as Beda Stadler described, journalists are also often unqualified and poorly informed to write about complex public health issues which can easily be misconstrued.

Suppression, Elimination and Eradication of Diseases

In most infectious diseases there are levels of circulating disease which are considered acceptable or unavoidable.  There are a few exceptions.  In the Covid-19 pandemic there is a lot of talk about suppression and elimination strategies.

Suppression is probably what we aim for in most diseases.  For example the bacteria  Salmonella which causes food poisoning: we know it’s around and causing illness amongst individuals; we treat cases; investigate where it may have come from; if we identify a source we put measures in place such as monitoring hygiene standards at a restaurant or removing potentially infectious chicken meat from a supermarket shelf.  Each disease response differs depending on multiple factors relating to the organism in question.

Elimination is the local or regional absence of a disease.  Australia has eliminated both Malaria and Measles, as examples.  We do still see these diseases (rarely), but they are not transmitted locally, so they are considered eliminated.  However they are both still of local public health significance.  The mosquito species that transmits Malaria are found in parts of northern Australia.  Theoretically, therefore, someone returning to Australia with Malaria could transmit to a mosquito vector which could then bite and infect a susceptible person.  Similarly, particularly with waning vaccination rates, a traveler returning to Australia with infectious Measles could transmit the virus to others, leading to an outbreak of local transmission.

The only infectious disease to have achieved global eradication is Smallpox.  Eradication was declared in 1980, over two hundred years after the first Smallpox vaccine was administered in 1796 and found to have worked.  The world is now on the cusp of eradicating Polio, which has been effectively vaccine preventable since the 1950s.  Polio vaccination was possible since the 1930s but paralysis and death in at least 15 vaccine trial recipients led to a twenty year hiatus in further vaccine trials, which is an example of the negative influence (rightly or wrongly) that fear can have on the capacity of public health interventions.

Influenza vaccines have been available and in use since the 1940s.  Despite this,  World Health Organisation say that Influenza causes 3 to 5 million severe illnesses and 290,000 to 650,000 deaths every year, mainly in high risk groups who are listed as children under 5yo, pregnant women, adults over 65yo and people with specific co-morbidities.  The numbers of influenza cases and deaths can vary significantly between years due to viral mutation combined with population immunity changes.

The worst influenza epidemic of the last century was Spanish Influenza in which up to 50 million people are estimated to have died at a time when the world population was 1.8 billion and populations were not as mobile, in the era before air travel.  So far to date, Covid-19 is estimated to be responsible for 680,000 deaths in a global population of almost 8 billion people.  This seems to put the Covid pandemic, although it’s still in swing, on a par with the 1957 Asian Flu Pandemic, which killed around 1 million people.

In a usual non-pandemic year, a healthy person presenting to an Emergency Department with mild to moderate symptoms of influenza who doesn’t need respiratory support is unlikely to be tested.  Go home, stay hydrated, take Paracetamol for your fever and stay away from others is the likely advice.  There is no contact tracing or enforced quarantine and the disease circulates amongst us, killing some along the way.  It is a dreadful disease but one we have accepted.  Cases who do get tested will be counted for monitoring purposes and the disease is also monitored by counting how many people present to health services with influenza-like-illness (ILI).  This all assists in collecting information about whether we are in a serious flu season or a mild flu season; what strains are circulating in order to assist with modifying next year’s vaccine; and other considerations.

In the Covid-19 pandemic aggressive suppression and/or elimination have been the aims of many countries, resulting in border closures, business closures, school closures, physical distancing rules, mask wearing recommendations, enforced quarantine and contact tracing measures.  One place where suppression measures were implemented lightly is Sweden, using the rationale that opening up after a hard lockdown would likely cause a major increase in cases.  They kept their primary and lower secondary schools open, banned public gatherings over 50 people, implemented voluntary recommendations such as working from home and avoiding unnecessary travel, promoted handwashing and physical distancing and put rules in place for places such as restaurants around physical distancing, without closing them down.

Fatality Rates

Sweden’s case fatality rate is reported as 7.1% but this is complicated by a number of issues which are discussed below and also in this detailed article.  Testing was prioritised to risk groups only, citing the well known public health doctrine that screening should result in meaningful action.  Their public health agency have remained transparent and open, providing accurate data and rationale for decisions, and admitting the mistakes that they made, the biggest one being that they didn’t implement protections in aged care facilities quickly or precisely enough.  Today Sweden are close to 0 daily deaths and life is reportedly close to normal again.  As testing has expanded, more positive test results with less deaths should see their fatality rate reduce significantly.

Fatality rates are complicated.  There are different ways to calculate them (eg case fatality is different to infection fatality), they change across time, especially in the early phase of an epidemic, and there are many other complexities involved that I am not qualified to speak on.  However I do know that these rates almost always reduce significantly as more becomes known about the numbers of people infected, which is inevitably more than the number of known confirmed or suspected cases, particularly in a disease in which many people experience no symptoms and therefore never seek health care.  As of this morning Australia has confirmed 17,282 cases with 200 deaths.  Our infection fatality rate is calculated by division of 200 by 17,282 and turned into a percentage by multiplying the result x 100.  So Australia’s current IFR is 1.15%.  As the pandemic evolves, this will obviously change.

There is no estimation in this crude calculation for such things as asymptomatic people who have not been tested (which would decrease the infection fatality rate) or the numbers of false positive test results (a known issue with these tests which I think, when accounted for, would likely increase the infection fatality rate?).  There is no breakdown of age distribution which likely raises the fatality rate in older groups and lowers it in younger groups; or co-morbidity which likely sees higher fatality rates in those with pre-existing heart and lung disease and much lower rates in healthy infected individuals.  Then there is the complication of whether you died “because of” Covid-19, or “with” Covid-19.  If you have terminal cancer with days to live and you test positive to Covid-19, should this be counted as a Covid death?

Questioning An Expert Opinion

This week I heard an interview with Raina MacIntyre, Professor of Global Biosecurity and one of Australia’s leading public health figures.  It is four minutes long and available at this Facebook link.  Her main points are:

1. Without a vaccine we can’t move on from our current public health response.
2. The pandemic is getting worse, the worst pandemic of anyone’s lifetime today, arguably worse than the 1918 Spanish Influenza.
3. Sweden allowed the disease to “rip through the community”, with no economic benefits and a much higher death toll, much higher burden on their health system and a lot of preventable deaths and illness.
4. Suppression is the right approach and there is no choice between disease control and the economy.
5. Outdoor gatherings are much safer than indoor gatherings without good ventilation.
6. Masks work by preventing transmission; people can have Covid-19 and be infectious but have no symptoms, so if you wear a mask in this circumstance you are less likely to spread it to others.  Wearing a mask when you are well can also stop you from inhaling infected droplets; and there is a lot of evidence for this including from a WHO-commissioned study on Covid-19, SARS and MERS.

I am nowhere near as informed or qualified as Professor MacIntyre.  But on a number of these points I feel her perspective is misleading.  And to support my daring to say this, I will share this article from Forbes magazine, and a response to it on Twitter by Francois Balloux, a geneticist at University College London who is involved in Covid-19 research.

You Must Not ‘Do Your Own Research’ When It Comes To Science

There are few articles I so viscerally disagree with. This piece champions a particularly vicious form of authoritarianism based on ‘expert’ knowledge. Everyone should be encourage to do ‘their own research’. It is the only path to a functioning democracy.  (Francois Balloux)