“The Covid vaccine will not be a panacea right away

and therefore our best vaccine remains the classic public health measures”

Interview: Dr Deoraj Caussy, epidemiologist

‘We have to be gingerly in not rushing to say that we have used WHO protocol effectively. The true litmus test is still to come during the re-importation of cases’


Dr Deoraj Caussy is a Canadian university graduate with double speciality in virology and epidemiology, holding PhD from McMaster University, Canada. He is a seasoned epidemiologist, having trained and worked in world-class premier institutes including the National Institutes of Health, Bethesda, and the Centers for Disease Control and Prevention, Atlanta, USA, as well as the World Health organization and the Ministry of Health and Quality of Life. He has managed many epidemics and the pandemic of H1N1 amongst other achievements. With this experience at both global and local level, he puts into perspective the apprehension caused by the recent new local case of Covid-19, comments on the protocol in place and shares his views on the recent promising developments in vaccine trials, and the roll-out.


Mauritius Times: It has taken only one Covid-infected patient to be walking around in the country, following discharge from the ENT, for this to create the apprehension of another lockdown amongst most of us. What do you think could have gone wrong in this particular case, and should we be worried?

As an epidemiologist, I examine the frequency and pattern of the occurrence of this event in order to generate a hypothesis and propose a solution.

Based on the information provided to us at this point, one can interpret the event in many ways: the simplest is to classify this as an atypical case displaying intermittent viral shedding. Intermittent viral load is usually seen for chronic viral diseases like hepatitis or HIV but not for acute coronavirus diseases so we should entertain alternative interpretation, taking into account all sources of variation.

There are at least three sources of variation; sample collection, test procedure and technician, and all three variations could account for this so-called atypical result. The samples may not have been collected and handled consistently in all three instances, the test parameters like laboratory reagents may not have been consistently applied in all three instances and, lastly, different technicians could have performed the three assays. One way to eliminate the variation scenario would be to repeat all three tests in parallel in an outside laboratory, failing which we cannot endorse the atypical case explanation.

Taken together, these observations are ground for grave concerns since we might wrongly misdiagnose a case as false negative and unwittingly allow the virus to seed in the community. This will have dire health consequences, as was exemplified during the first wave.

* WHO’s technical guidance for ‘discharging patients from isolation without requiring retesting’ states: For symptomatic patients: 10 days after symptom onset, plus at least 3 additional days without symptoms… and for asymptomatic cases: 10 days after positive test for SARS-CoV-2. Could it also be that the protocol put in place by the health authorities has not been rigidly followed in that particular case and for others as well?

These protocols need to be examined in local context and re-defined, if needed, as the WHO guidelines are generic in nature. Adherence to the national protocol has to be continuously monitored to ensure consistent application especially when we have new personnel, equipment, etc. Being given the turn-around of health personnel, without regular training, it is conceivable that there is room for many human errors.

* There are allegations of “deux poids et deux measures” when it comes to discharging patients or inbound travellers put in isolation here. You would like to think that is not true, isn’t it?

In public health, the protection of the society takes precedence over the rights and privileges of an individual, irrespective of origin or status. Therefore, a protocol must be adhered to in all circumstances and by everyone unless there’s a pressing demand of a matter of life and death. Being given the precarious nature of the virus shedding and the presence of asymptomatic subjects that already poses serious challenge to health risk management, any deviation from the protocol is a recipe for a disaster in the making and should not be tolerated under any circumstances.

* We however hear some doctors saying that the WHO protocol/technical guidance with respect to the Covid-19 pandemic would have not proved effective in some countries. That sounds farfetched. Don’t you think it’s serving us well?

The World Health Organization has contributed to health improvement in many domains around the world, and their work deserves to be applauded. However, it must be remembered that WHO’s role and function are limited to norms and standards and it is, generally, not in their terms of reference to design a national protocol.

WHO provides a one-size fit all approach, and its recommendation remains generic. It is up to the national government to use the WHO guideline to formulate its own national policy based on local prevailing conditions with inputs of track-record scientists.

If we say the WHO protocol had been successful, on what basis are we claiming this? In public health the philosophy is to prevent mortality and mobility before disease strikes. The hallmark of success is a preparedness plan and an appropriate timely response, as exemplified by Thailand and acknowledged by WHO. This country for its size was able to maintain its mortality rate to well below 0.04% because it had a preparedness plan that was rolled out when the time was necessary.

When we look back at the epidemic in Mauritius, it is clear that we acted in a tardive and hurried way due to lack of preparation and effective response, all this despite public outcry in the media of the importance of testing asymptomatic subjects, endorsing the wearing of masks to break the chain of transmission and having a well-versed preparedness plan supplemented with the stockpiling of the required medication and supplies. These health policy recommendations were made right from the time when the epidemic first raised its head.

We have to be realistic when we talk of success or effectiveness of the control in Mauritius: is 10 avoidable deaths, including a highly proficient physician and other frontline workers a sign of success? So, we have to be gingerly in not rushing to say that we have used WHO protocol effectively. The true litmus test is still to come during the re-importation of cases and the flaring up of a local epidemic in the event of a second wave. If lessons derived during the first wave can be successfully applied to the second wave, then we can talk of success; else it would be a hit and miss health policy.

* Mauritius’ health authorities and the frontliners must have gathered sufficient exposure to and experience in managing the Covid threat. Is there room for adaptation of such protocols, like the WHO’s, to our country-specific conditions?

A resilient health system is one that evolves with time and adapt to save and protect lives and as such has to be continually updated. The recent incident of a case that went undetected in the community highlights definite caveats in the existing protocol. There is room for improvement at three levels.

First, we should adhere to a consistent quarantine policy. Secondly, when we release a previously known positive case in the community, we should follow them for a longer period either by phone or visit and, if necessary, repeat the testing. Third, we should introduce and use a serology test that has not been validated.

* There has been a lot of excitement following Pfizer’s announcement of its interim results from their Covid vaccine trial. The vaccine was reported to have an “efficacy rate above 90%”. That’s indeed a breakthrough, but does efficacy in vaccine trials in the lab necessarily translate into that same level of effectiveness when it comes to the treatment of a disease?

It is rare that we can proceed from laboratory to field conditions and expect the same result for a vaccine trials. First of all, we must remember 90% efficacy is only a preliminary result, and when the final result comes the number may be higher or lower.

Nonetheless 90% efficacy is a very good starting point. However, under field conditions there are technical, financial and social issues that have to be overcome before we can successfully implement the vaccine trial.

* Zania Stamataki, who teaches viral immunology at the University of Birmingham states: ‘Very few vaccines – aside from measles and chickenpox – are 90% effective… the flu vaccine is around 40%-60% effective, but it still saves millions of lives. And that’s something to celebrate.’ What’s your take on that?

The professor is referring to the immunological phenomenon known as cohort or herd immunity, whereby you need not immunize the whole population to get protection. But for herd immunity to work, two conditions must be met: first, the disease must have a single host and, second, the infection leads to lifelong immunity.

Well, we know that the coronavirus has an animal origin and recent observation of the mink population in Denmark has shown that the virus can go back to the animal kingdom and reemerge to infect human beings, so that presumption is compromised.

As far as the second point is concerned, we currently do not have enough information to know whether the virus leads to lifelong immunity over there doesn’t that’s because the disease hasn’t been observed for a long enough time. The degree of protection is also contingent on being able to protect the vulnerable group i.e., the older individuals who generally respond poorly to vaccines because as one ages the immune system undergoes a phenomenon known as immune senescence. This hampers the delivery of vaccines to older individuals for whom often time more special vaccines had to be made like in the case of pneumococcus or shingles.

* There are also the issues of the distribution of an approved Covid-19 vaccine and its cost, as it does not appear as of now that it will come cheap. Some countries are going for side agreements with pharmaceutical companies to ensure early access to a vaccine. What would you suggest to our health authorities on the way to proceed in that regard?

Due to the substantial cost of R&D, vaccine manufacturers preemptively sell their vaccines through an Advanced Purchase Agreement (APA) and many developed countries have already put their bids to one or more vaccine manufacturers, putting the developed countries out of competition.

In order to ensure vaccine availability, WHO in alliance with other international partners, is promising a certain number of vaccine doses to developing countries through their program known as the Covax. We know from the H1N1 pandemic the vaccine promised by WHO was not delivered on time and given the competition from developed countries to bid for advanced purchase agreements this makes our condition very precarious in the immediate future. Our only hope for now is the classic public health approach of wearing masks, practising social distancing and hand hygiene.

* Will we out of the woods once an approved Covid-19 vaccine becomes available, and shall we be able to go back to the ‘old normal’ in the way we live, socialise, work, travel, etc?

Looking at the epidemiological patterns of the disease, it is clear that this virus will continue to spread around the world so long as the level of contamination doesn’t reached about 70% uniformly worldwide. I do not see this happening in the near future of one year, but it will take longer, assuming the condition remains constant that is the virus doesn’t mutate or becomes more virulent.

For these reasons, the vaccine will not be a panacea right away and therefore our best vaccine remains the classic public health measures: wearing a mask, practicing social distancing and breaking the chain of transmission of the virus by frequent disinfection of hands and contaminated surfaces.


* Published in print edition on 17 November 2020

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