COVID-19: A risk management strategy – Prof. Neville Calleja

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By Prof. Neville Calleja, Associate Professor at the Faculty of Medicine & Surgery 

nevillecallejaIndeed, the COVID-19 pandemic has been a game changer for many of us. Public health, from being regarded by many of our clinical colleagues within the same Faculty as a ‘Cinderella’ speciality, has been thrusted into the foreground and had to hit the ground running and evolve and fine tune itself as a profession in a continuous and highly responsive manner as the demand increased and the challenges have been morphing at a fast rate.

Many of the countries whose populist administrations have suppressed the public health profession for so long that it could not manage to get the ear of the political class, are now experiencing major loss of life.

Indeed, many of the countries whose populist administrations have suppressed the public health profession for so long that it could not manage to get the ear of the political class, are now experiencing major loss of life.  Luckily, this was not the case here in Malta.

Whilst the public health profession has had to initially compete with other voices, particularly from the business sector, we have now achieved a fairly universal understanding, even with this sector, and the political class has been indeed listening to our messages.

It is amazing that practically all sectors, including academia, are now rallying around public health supporting to their utmost.  It has almost become a challenge to manage all offers for help.

As a result, the now famous baseline reproduction number (the baseline number of persons each case would infect, Ro) of 2.2 that has been consistently observed in most countries around the world, has never been observed here to date as our effective reproduction number (the effective number of persons each case would infect, given the measures in place, Rt) has never risen above 1.5, as already reported elsewhere.

Nonetheless, the tendency of the reproduction number is to spring back to 2.2, so keeping it low requires effort… a lot of it.  An Rt of 1.5, whilst definitely better than 2.2, is not something to rejoice about, as it still leads to thousands of hospitalised people at any point in time and thousands of deaths.  The Rt to aim for would be under 1.0 (one person infecting less than one other person), because that means that the epidemic is now on the way down. In effect, when we refer to flattening the curve, we mean effectively pushing the reproduction number from 2.2 to somewhere above 1.0. This means that the same cumulative number of hospitalisations would be reached albeit over a longer period of time, as the limiting factor would only be the population size.  In the above scenario, herd immunity would still be achieved but at a massive cost in terms of loss of life.  There is one advantage in flattening the curve in terms of deaths.  It is becoming increasingly evident that the mortality rate is a function not only of the nature of the illness but also of a country’s hospital and intensive care capacity.  Effectively, when intensive care capacity is exhausted, most patients requiring intensive care would simply overflow into the mortality group. Nonetheless, restricting Rt to below 1.0 would then be effectively chopping off the curve and forcing it to go down before the whole population gets infected.  This would be the ideal situation in terms of morbidity and mortality, but not in terms of herd immunity.

However herd immunity can be achieved through vaccination at a later stage, if we can avoid importing any new case till then.  Alas as terrible as the onslaught is right now, in many of the continental European countries, it could in reality have been worse had most countries not implemented lock-downs. This also means that herd immunity may not be achieved on the continent either.  Once lock-downs are relaxed anywhere in Europe, if relaxed too early, the risk of a second wave would be high.  One has to be keep in mind that Europe presents us with a scenario of similar epidemic curves, some flatter than others, and all out of phase in terms of time. For example, the figures observed in the UK were following the same course observed in Italy four weeks earlier.

Where does that leave Malta?  I believe you may have already deduced the answer by yourselves.  The best scenario for our population would be to suppress Rt to below 1.0 and keep the width and the height of the epidemic curve quite limited. We then need to make best use of our insularity to keep avoiding imported cases and rekindling the epidemic. So effectively, our population has two Achilles heels that could hinder our success in controlling the epidemic.

The first one is the elderly dependency ratio of our population.  Our vulnerable population is rather sizeable in proportion and we therefore have a risk that the infection, if unrestrained, could wreak considerable damage on a larger proportion of our population than observed in other countries. That is why we are also implementing, to a massive extent, what the Irish have termed as ‘cocooning’ – which should lead to further protection of the most at risk of morbidity and mortality in the population.  That way we can further reduce the burden.The second Achilles heel is our migrant population.  We are all aware that some of the migrants in Malta, economic or otherwise, are living in relatively high-density accommodation.  Many of them also have a language barrier and struggle even with English.  Their employment terms may not be as flexible and resilient as those of the average Maltese.  All these factors make it more difficult for a migrant not only to learn more about the precautions that one should exercise but also to come forward at the slightest hint of a cold to be swabbed and possibly remain in isolation for a number of weeks, with no income.  We have tried to produce learning materials in as many languages as possible to try and mitigate the knowledge gap. But this does not address all concerns expressed above.Alas, now we have seen the epidemic gain some ground within the Safi Open Centre.  It will not be easy to manage.  However, controlling the infection within this group is imperative for two reasons: (a) even if many look young and healthy, there are some who are not and therefore this could be a very material threat to the wellbeing of the members of the community, and (b) active spread through this community is likely to spill into the Maltese resident population threatening our vulnerable and potentially overwhelming our ‘cocooning’ measures.Therefore, I shall end this post with an appeal. Many fellow academics of the University of Malta are heavily involved in NGOs working for the safety and well-being of migrants.The public health effort, especially in migrant communities, needs the assistance of these NGOs to explain and make clear to the migrants themselves why the public health authorities are imposing these restrictions on them and asking them to take swab tests and how this will not only benefit the Maltese population, but also the welfare of their own community within the Safi Open Centre and in other similar communities.


Prof Neville Calleja qualified as a medical doctor in 1999 and proceeded to study Medical Statistics and Public Health after his medical training. He qualified as a specialist in public health medicine in 2006 and was awarded Membership of the Faculty of Public Health in the UK in 2011. In 2013, Neville completed his PhD studies on the statistical correction of misclassification of disease status between self-reported and examined health surveys.

He has been employed at the Directorate for Health Information and Statistics within the Ministry responsible for Health since 2001, taking on its helm in 2007, and also served as Acting Chief Medical Officer during 2014 and 2015. As part of the Chief Medical Officer’s office, Neville has been long involved in the drafting of strategies and the planning of capital projects within the Ministry for Health in Malta.

Prof Calleja has fifteen years of experience lecturing medical statistics, epidemiology and public health to all health care professionals, together with ethical and scientific review of projects at local and international level.

He is also active at European level in the field of Health Information for both the European Commission and WHO (Europe), as chair of the European Health Information Initiative within WHO(Europe). Prior to this, he was the first chair of the Small Countries Health Information Network for WHO(Europe) and he is still an active member of the WHO Collaborating Centre for Health Systems and Policies in Small States within the Islands and Small States Institute within the University of Malta.

Prof Calleja has been active on a number of collaborative research projects, particularly in the area of health information, funded by the EU Public Health Programme, and also the EU Research Framework Programmes. He has also been in receipt of EUROSTAT grants for development of statistical framework at national level. Within his latest project, JA InfAct, he is leading an exercise which is piloting a WHO-designed peer-review health information system assessment methodology in nine participating countries.

Disclaimer: Opinions and thoughts expressed within this article do not necessarily reflect those of the University of Malta.  

Prof. Neville Calleja – M.D., M.Sc. (Lond.), M.Sc.,PhD (Open), M.F.P.H.,C.Stat.,C.Sci.,F.R.S.P.H.,D.L.S.H.T.M.

Prof Neville Calleja qualified as a medical doctor in 1999 and proceeded to study Medical Statistics and Public Health after his medical training. He qualified as a specialist in public health medicine in 2006 and was awarded Membership of the Faculty of Public Health in the UK in 2011. In 2013, Neville completed his PhD studies on the statistical correction of misclassification of disease status between self-reported and examined health surveys.

He has been employed at the Directorate for Health Information and Statistics within the Ministry responsible for Health since 2001, taking on its helm in 2007, and also served as Acting Chief Medical Officer during 2014 and 2015. As part of the Chief Medical Officer’s office, Neville has been long involved in the drafting of strategies and the planning of capital projects within the Ministry for Health in Malta.

Prof Calleja has fifteen years of experience lecturing medical statistics, epidemiology and public health to all health care professionals, together with ethical and scientific review of projects at local and international level.

He is also active at European level in the field of Health Information for both the European Commission and WHO (Europe), as chair of the European Health Information Initiative within WHO(Europe). Prior to this, he was the first chair of the Small Countries Health Information Network for WHO(Europe) and he is still an active member of the WHO Collaborating Centre for Health Systems and Policies in Small States within the Islands and Small States Institute within the University of Malta.

Prof Calleja has been active on a number of collaborative research projects, particularly in the area of health information, funded by the EU Public Health Programme, and also the EU Research Framework Programmes. He has also been in receipt of EUROSTAT grants for development of statistical framework at national level. Within his latest project, JA InfAct, he is leading an exercise which is piloting a WHO-designed peer-review health information system assessment methodology in nine participating countries.

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