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Dhaka Tribune

Will Bangladesh be able to flatten the curve?

We need to rethink our approach to fighting Covid-19

Update : 18 Apr 2020, 08:43 PM

The Covid-19 outbreak in China was declared as a public health emergency of international concern by WHO on January 30, 2020 -- a country that has close ties with Bangladesh, with people continuously travelling back and forth.

There were no travel restrictions or screenings in place until March. News reports also show that there has been a ten-fold increase in respiratory diseases compared to last year. However, none of these were tested for Covid-19. There were many who contracted fever and pneumonia before the official Covid-19 case was reported in the news.

The first official case of Covid-19 was reported on March 8; however, the country did not go into lockdown until March 26. We can safely assume that community transmission started long before the official reports declared community transmission, and testing was limited at that time as the criteria to get tested involved travel to infected countries. 

One has to wonder how long Covid-19 has silently been spreading in the country, how widely the infection has already spread, how many Covid-19 related deaths have remained under the radar in the guise of pneumonia-related deaths, and more importantly, how many have already recovered from it.

Even now, the official numbers are not representative of the actual numbers, as testing remains limited and we have one of the lowest test rates in the world. However, this is still an increase in terms of testing and test centres in comparison to the past few weeks.

The increase in testing has created an impression that the infection is suddenly spreading as the numbers spike. It is only because we have increased testing that we are seeing a rapid increase in numbers. It does not mean the infection has suddenly started spreading now -- it was already spreading; we were just not testing for it. 

When the “general holiday” was declared on March 25, there was a mass exodus from Dhaka to other parts of the country, with general confusion surrounding the gravity of the situation since it was called a holiday. People seemed to be in vacation mode, travelling freely with very little awareness of socio-physical distancing.

Around April 4, we had another mass movement of people due to the confusion regarding RMG factories opening up. Congregations and Friday prayers at mosques were not suspended until April 6. Between the mass exodus, the mosques, and the RMG debacle, we can assume the infection has spread far and wide within the country.

Even as recent as April 15, we saw pictures of wet markets teeming with people as though we were not in a pandemic situation, and the RMG protests are still continuing. On social media, we get to see people pretending to be practicing socio-physical distancing when the enforcement authority is around, but not paying heed to it otherwise.

Given our population density and this lack of awareness among the masses regarding the importance osocio-physical distancing, and also taking into account the exponential rate of transmission of the virus, we may have reached a point where we need to start mass serological testing for post-recovery antibodies to see what percentage of people have already been through the infection and developed temporary immunity.

Can we actually flatten the curve?

The “flatten the curve” model is one that was devised for countries with a proper health care system, with a view to help out the system itself and lower the death toll -- a non-pharmaceutical intervention (NPI) to mitigate the intensity of the outbreak by not overwhelming the critical care capacity. 

Both UK Prime Minister Boris Johnson and US President Donald Trump, however, had initially opted for a herd immunity strategy in the UK and the US respectively, until it backfired on them, because in their countries they could actually flatten the curve.

Not flattening it by adopting a herd immunity approach came at a much higher cost in the form of a higher projected death toll, one which would have been preventable in their infrastructure if they had simply adopted a different strategy. Countries like the UK and the US can also subsist in an extended lockdown through isolation and welfare packages, given their high-income economic status.

At present, these countries are considering an intermittent lockdown strategy in which they periodically lift the lockdown when transmission subsides, and then reinstate the lockdown when it flares up again. With this strategy, they can mitigate the situation for a prolonged period of time without overwhelming the health care infrastructure, as they slowly edge towards herd immunity. A strategy that South Korea and Singapore are already implementing.

Studies show that a complete lockdown will send the curve right back up as soon as they open up, because people will have no immunity in a total lockdown that suppresses transmission completely, and the infection will surge as soon as the lockdown is lifted. 

Opening it up intermittently, especially for non-risk groups to go back into society does not cause the surge, and allows the health care system to provide critical care, while continuing to ramp up critical care capacity.

The “flatten the curve” model, however, does not fit our context. We did not have the health care or the economic infrastructure to begin with -- a key metric in the success of flattening the curve. Even if we were functioning at full capacity, we did not have a comparable health care infrastructure, and at present, after more than a month of the first official Covid-19 case was reported, we are yet to increase our critical care capacity.

There is talk of private hospitals being declared as affiliates, temporary clinics being set up, and increasing critical care capacity -- however, it is still all in the form of vapourware; a lot of plans are yet to materialize. More importantly, we do not have the economy for a sustainable lockdown for the same length of time. With a large percentage of the population that does not have a disposable income to sustain themselves through a lockdown, people are faced with the prospect of starvation.

We are less than a month into lockdown and despite having available funds, we are unable to implement proper distribution of aid because there is so much pilfering within the system. Hence we have a lockdown of the workforces, with people gravitating towards starvation, but not a lockdown that is preventing the spread of the virus. Unless we figure out a proper food distribution system, people will starve to death.

There will be a cascading effect with complete deterioration of law and order if people are starving. How does it make sense to lockdown to prevent people from dying, only to have more people die from the lockdown? 

We need to think of a more contextualized strategy, one that makes sense in our socio-economic and health care infrastructure. We could consider undertaking mass serological testing for post-recovery antibodies in order to test people’s immunity. Once it becomes possible to conduct mass serological testing for immunity, we could consider allowing people that test positive for post-recovery antibodies to go back to work.

Serological tests for immunity are based on ELISA (enzyme-linked immunosorbent assay) technology that tests for antibodies produced as a response to the Covid-19 (SARS-COV-2) infection, with specific antibodies that are detected in higher levels post-infection. There are a number of companies producing these tests worldwide, and they are calibrated for sensitivity vs specificity in terms of performance, with a margin of error for false negatives and false positives.

Sensitivity is the ability to detect the antibodies in the first place, while specificity detects the right type of antibody. The tests can vary in terms of the performance of these two. However, a test for immunity looks for a higher specificity performance in order to rule out false positives. 

A false positive means the person tested is not immune even though the test says they are, whereas a false negative means the person might be immune but it did not show up in the test. Hence a false negative is a more desirable result than a false positive in regards to immunity testing.  

We also need to scale up the current Polymerase Chain Reaction (PCR) tests to detect the spread of the infection, and implement aggressive contact-tracing measures in order to not let the virus run amok. However, at this point, instead of only testing for infection and continuing to lockdown haphazardly while gravitating towards starvation, we can implement mass serological testing for immunity to understand what percentage of the population is already exempt from socio-physical distancing and can possibly return to work, in tandem with diagnostic PCR tests for infection, contact-tracing, and quarantine to contain the spread. 

Of course, the vulnerable part of the population that comprises the high-risk group will still have to maintain strict socio-physical distancing and self-isolate. The serological tests for immunity will also help us identify potential blood donors for critical patients, as studies show that convalescent plasma transfusion from patients who have recovered has been very effective in neutralizing Covid-19 viremia in severe cases.

All of the above is contingent on the duration of immunity after recovering from a Covid-19 infection. At present, the transmission dynamics and duration of immunity is informed by the data modelling of other betacoronaviruses of a zoonotic origin, such as HCoV-OC43 and HCoV-HKU1 (human coronaviruses that are the second most common cause of the common cold), MERS coronavirus, and the closest genetic relative of covid-19 (SARS-COV-2) -- the SARS-COV-1 coronavirus.

In case it has the same duration of immunity as seasonal coronaviruses, then immunity can be for less than a year and we will be back to square one in the next seasonal outbreak. However, the fact that the closest genetic coronavirus SARS-CoV-1 has an immunity of two years, a relatively similar duration of immunity for Covid-19 looks likely. There is also a possibility of cross-immunity from other betacoronaviruses, which may stretch immunity to approximately three years.

Research into the duration of immunity is important to understand how we can bide time until a vaccine becomes available. Long-term prospects in terms of the global situation regarding the pandemic depends on duration of immunity and vaccine efficiency.

Demographically, we are at an advantage because our median age is in the 20s, with a low percentage of elderly population; the age-structured data from other countries show that the risk of mortality for Covid-19 increases precipitously with age. 

Studies also show that trained immunity from the BCG vaccination, which is mandatory in Bangladesh, may be able to provide cross-protection from Covid-19 -- we do not have data for Covid-19 yet, but there is ample data on cross-protection for secondary infections from other unrelated pathogens.

Given our context, even with a lockdown, we do not have the testing capacity or the treatment capacity to flatten the curve, and we will also have people dying from starvation. Therefore, we need to rethink our own approach by drawing on the experience of other countries while contextualizing it, given our very disparate realities.

Naira Khan is an Associate Professor of Linguistics at Dhaka University. She is also a member of Jagoree.

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