Medical workers examine sellers at a traditional market in Batam, Riau Islands, last month. (Antara Photo/M. N. Kanwa)

Superspreaders Dictate Covid-19's Transmission in Indonesia


JUNE 30, 2020

Jakarta. A recent paper by Indonesian scientists has pointed to the oversized role of a few highly contagious individuals in the Covid-19's transmission in the country, partly explaining how the world's fourth most populous country fared better than its peers like India, Brazil and the United States. 

The pre-printed paper, titled "Superspreading in Early Transmissions of Covid-19 in Indonesia," underlined the need to avoid mass gathering to limit the chance any superspreader infects a large number of people. It also highlighted the need to implement speedier tracing and testing to identify and isolate the potential spreaders before they can affect more people. 

Indonesia first confirmed two Covid-19 cases on March 2 and since then has reported more than 56,300 cases in total, or 197 cases per million of the population. 

That was better than India that reported 397 cases per one million people, or Brazil (6,324) and the United States (7,701), according to data compiled by Oxford-based research organization Our World in Data.  

While the paper acknowledges the limited number of testing and the large scale social restriction might contribute to the relatively low number of cases, the disease's dependence on few superspreaders might also explain the Covid-19 spread in Indonesia. 

The study analyzed 397 first confirmed cases in Jakarta and its satellite city Depok and Batam in the Riau Islands at the onset of the pandemic from March to April. The study found 15 percent of Covid-19 patients were responsible for 80 percent of the cases.

These superspreaders stoke up the basic reproduction number (R0), a key parameter in epidemiology that represents the average number of people infected by a person with the disease, initially, when there are no restriction measures curb the epidemic from spreading. 

The paper estimated the R0 was 6.79 for Jakarta and 2.47 for Batam. 

"In Jakarta, a superspreader infected 52 people. That case raised the R number, while most of the infected person did not transmit the disease at all," Agus Hasan, an Indonesian researcher at the University of Southern Denmark, who was one of the paper's writers, told the Jakarta Globe on Tuesday.  

To further validate their finding of superspreaders, Agus and his cowriters estimated the overdispersion parameter (K). Small K value reflects extreme transmission cases having a high impact on the reproduction number. The scientists determined the K value was at 0.08 for Jakarta-Depok and 0.2 for Batam. 

Agus said that meant rapid identification and isolation of a superspreader should have curbed the outbreak effectively.   

"The smaller the parameter (less than one), the better, because that means [the disease] is easier to control," Agus said. 

On the other hand, failing to identify even just one superspreader meant that the disease could linger in an area and break out again in the future, the paper suggested. 

Agus said the nature of how Covid-19 spreading in Indonesia should dictate how the country returning to its normal activities. 

"In my opinion, at least two things must be prioritized. First, the activities with close interaction, especially religious activities, work in factories, and weddings must be strictly regulated. In Jakarta and Batam, the super-spreading events were religious ones," Agus said. 

"Second, speedier testing using PCR test and isolation. The delay between [swab sample collection] and test result must be as short as possible," Agus said. 

Local epidemiologists said it took one to two weeks for Indonesia to confirm a person infected with Covid-19 from infection as the country lacks testing capacity.  

The World Health Organization, in its latest situation report last week, said that only Jakarta, out of 34 provinces in Indonesia, had conducted one PCR test per 1,000 population per week. 

The capital has confirmed more than 11,400 cases, the second-highest after East Java. But less than 8.4 percent of the patients in Jakarta needed hospitalization with case fatality rate now hovers around 5.7 percent.

Jakarta started to ease its restriction early this month, allowing houses of worship, offices, parks, and shopping malls to operate at 50 percent of their capacity.

Since then, the number of Covid-19 cases in Jakarta has picked up, already exceeding its April peak. But, Jakarta Governor Anies Baswedan said last week that the increase was the result of the city expanding testing and tracing capacity.

The governor expresses his confidence in the city's current Covid-19 surveillance capability, saying that now less than 5 percent of the city's tests turned out positive.

"In the past, we did a lot of tests on those who had symptoms. Now we actively trace and test people [without symptoms]," Anies said.