Covid-19 transmission rate below 1 in Dhaka, but danger still looms

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Data from the Directorate General of Health Services (DGHS) show the coronavirus spreading faster outside Dhaka, while the first and the biggest epicenter of the virus in Bangladesh seems to be entering a declining transmission stage.

Experts believe that even though the numbers are coming down, the chances of a second surge in transmission are still there.

Pointing to the lesser number of tests conducted in the country in recent times, they said the authorities could not afford to relax on implementing preventive measures.

Alamgir Hossain, principal scientific officer at the Institute of Epidemiology, Disease Control and Research (IEDCR), told DT that the reproduction rate (Ro), otherwise known as the transmission rate, had gone down to below 1 in the capital city.

The transmission rate of a virus is a measure of its transmission or the number of new infections generated by each case. A transmission rate of 1, for example, means that on average each infected person will infect one other person he or she comes in contact with.

A transmission rate of 1 or higher indicates a rapid spread of an illness, while the number under 1 indicates a decline in the spread during an epidemic.

However, Alamgir Hossain said it was not their calculation and the time had not yet come to suggest that the transmission rate was in decline.

The Institute of Health Economics and DGHS are jointly working on calculating the number of transmissions.

Associate Professor Shafiun Nahin Shimul of the institute, who is working on the projection, told DT that although the quality of data and number of tests remained a concern, the information provided by the DGHS showed that the transmission rate in the city had been at a stable situation for a while.

However, the number of cases increased massively in June, he added.

He said at the end of May the authorities had calculated the transmission rate to be little more than 1, while it arguably came under 1 at the end of June or early July.

It would be difficult to speak of the actual situation of Dhaka city as the data on the government website did not provide any update on some 40% of the cases, he explained.

The associate professor, however, warned that the promising situation might turn into a nightmare if preventive measures, especially those related to hygiene activities, were not implemented properly.

An analysis of data covering a 10-day growth factor of coronavirus revealed that in the first 10 days of June, Dhaka city had 15,583 new cases.

The number was 17,846 in the subsequent 10 days of June and 18,308 in the last ten days of June. The data showed that the growth rates came down in the last 10 days of the month.

In the first ten days of July, 14,398 new infections were reported in the city, giving a clear indication that the growth rate was decreasing.

Among the 94,394 infected in the city, some 47,967 people had recovered by July 10.

“In Saudi Arabia, the transmission rate went under 1 [0.93] so the authorities there relaxed preventive measures. As a result, the transmission rate crossed the threshold of 1 within a few days, forcing the authority to resume preventive measures again,” he added.

Although conditions in Dhaka have been getting better, they were yet to be similar in the rest of the country.

The estimated Ro for Bangladesh is 1.47 (as of July 10th). Shaun said this could be another ticking bomb for the city as the public movement had already been eased and preventive measures compromised.

The low number of tests

On July 10, the National Technical Advisory Committee (NTAC) advised the authorities to improve the quality of tests and to introduce the antigen coronavirus tests to make it available for all.

During this time the number of tests saw ups and downs in its trends while maintaining a steady increase in the total number of tests.

But the number took a sharp decline after July 2, two days after the country had conducted its highest tests (18,426) in a single day.

Since then the number of tests never reached 16,000 marks and mostly limited to 11,000 to 14,500 tests.

DT could not ascertain the number of tests done in each district from the DGHS. As such, it could not be known how many tests were conducted in Dhaka city alone.

One of the members of the NATC committee, virologist Prof Nazrul Islam, said Covid-19 tests needed to be available for everyone to have a better understanding of the current situation. Lesser numbers of tests could cause the authorities to underestimate the situation.

Seeking anonymity, an official at the DGHS said as there was a lack of consistent data it could be difficult to comment on the transmission rate going down.

But what was happening around could give a sense of the situation, he said, adding that a good number of beds at the COVID dedicated hospitals in the city were vacant right now while the number of patients was higher in comparison to beds till June 20.

He said they used to receive messages or calls from government officials or local representatives to test 250-350 people daily at the end of June. However, on July 10, they got only 79 such testing requests.

These two incidents mean people were getting used to the virus, regaining their confidence as they were witnessing lesser infections now and most importantly lesser new cases right now.

Public Health expert Prof Shah Md Monir, who is also a member of an eight-member expert committee formed by the DGHS designated to monitor measures taken by the health services in Dhaka division, told DT that the transmission rate was 1.05 as far as he was aware.

This is indeed good but the city needs to have the transmission rate come down to under 1, he added.

“The growth rate is not at a declining phase, rather the city is in the plateau,” the former DGHS director-general added, saying: “Whether we have a second wave of peak or not, or whether the current status remains stable will depend on how we are dealing with the cattle market during the upcoming Eid.”

Report- Dhaka Tribune

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