Fish in Singapore is still safe for consumption, although it is likely that the Jurong Fishery Port cluster cases came from Indonesian or other fishing boats and via multiple points, said Singapore's director of medical services Kenneth Mak yesterday.
"We have no evidence to suggest that transmission is occurring through contaminated fish. We believe that the fish that we still consume and enjoy remains safe for consumption," he said at a press conference held by the multi-ministry task force tackling Covid-19.
There are now 321 cases linked to the Jurong Fishery Port cluster.
"This number will rise as we find more cases at these places and in the other wet markets," said Associate Professor Mak.
Infections have been detected at a total of 28 markets and food centres, Health Minister Ong Ye Kung said at the press conference yesterday. The number was raised to 35 last night.
Prof Mak added that tests of the first group of cases have identified the Delta variant to be the cause of Covid-19 infections in this cluster.
"The identified variant of concern has features that are similar to what we've seen in other cases that we have picked up in imported cases from Indonesia," he said.
"So we believe that Covid-19 infection in this cluster has been introduced, perhaps via sea route, into the fishery port, likely from Indonesian or other fishing boats that have brought fish into the port. The exact mechanism of transmission from the boat to people who operate stalls in the port isn't entirely clear."
He added that tests also suggest the clusters linked to the fishery port and wet market may not have been due to a single point of introduction of infection.
"Exposure may have occurred over a period of time, with multiple points of injection of infection because the genetic information for variants that we've identified so far is not completely identical across the different cases."
"So we are not able to determine how long these episodes of introduction have occurred over or who might have been a specific super spreader leading to the cluster that has emerged."
At least one Covid-19 patient who worked at the Jurong Fishery Port frequented a KTV lounge within the infectious period, he said.
"It is, however, not possible for us to verify whether that individual did transmit an infection because the diagnostic PCR (polymerase chain reaction) test performed on that individual detected the presence of Covid-19 virus, but it was at a very low count," said Prof Mak, adding that at such low viral loads, there is not enough of the virus to carry out the tests.
He added: "From the public health perspective, it is less important for us to confirm that link between the fishery port and the KTV lounge. Irrespective of how transmission has taken place, there are cases and growing clusters in each setting.
"The numbers of cases that we're picking up from the wet market testing continue to grow, and this remains a cause for concern."