News Analysis: What do the numbers tell us?

The “general holiday” announced by the government initially from March 26 and then extended in phases is due to come to a close on May 30. The question remains as to how effective the shutdown has been and whether it should be extended even further.

In the absence of widespread testing it is difficult to determine just how prevalent the virus is throughout the country, which makes both measuring how effective the shutdown has been and determining whether or not it would be wise to extend it difficult.

With many countries around the world starting to lift their lockdowns and gradually easing back to business as usual, we need to determine what Bangladesh should do.

Typically, the markers for easing lockdown are determined by the estimated number of cases in the population at large. Germany, for instance, has determined that it will re-impose restrictions if cases rise above 50 per 10,000 of the general population.

Authorities in Bangladesh remain disinclined to measure the level of the virus in the general population and resources to even do so are very limited.

How then should we take the decision?

One way is to look at the percentage of Covid-19 tests that come back positive. This is not a foolproof indicator, but assuming that the protocols for who gets tested have remained roughly standard, the numbers should provide a decent picture of the prevailing trend.

It is not really helpful to compare the percentage of tests that came back positive before March 26 and the percentage that did afterwards, as the increase there can largely be explained by a steep increase in the numbers tested.

As recently as April 2, the test positivity percentage was below 2% but this was largely due to the fact that only a few hundred were being tested daily, a sample size too low to represent anything meaningful.

However, as testing expanded into the thousands -- it currently stands at roughly 10,000 a day -- a usable picture starts to emerge.

Since April 12, the test positivity percentage has dipped below 10% only twice and even then only fractionally; it has never dropped below 9% since that date.

This gives us a fairly robust data set to work with.

It should be noted that test positivity percentage has been rising by the day over the past week. It crossed 17% for the first time on May 21, stayed above 17% for four days in a row, and yesterday crossed 20% for the first time.

The key date to look at in terms of a before and after comparison is perhaps May 10, when shopping malls were re-opened, when the lockdown was substantially eased.

In the two weeks prior to this re-opening, the average daily positive test percentage was 12.21%.

In the two weeks after the re-opening, the average positive test percentage has been 15.86%.

And, most worryingly, in the past seven days, the average positive test percentage has been 17.25%.

In short, it would appear that the virus has become measurably more widespread since the lockdown was eased on May 10 and that the numbers are increasing by the day.

Given the fact that the numbers are on the rise, it is worth considering whether the current plan of lifting the lockdown after May 30 remains tenable.

And even if other factors make lifting the lockdown unavoidable, we should be in no confusion as to what awaits us: the month of June will likely see an explosion of new cases, and we need to be prepared.

Test positivity percentage in April-May