More than 40 different coronavirus tests have been authorised for use in Singapore over the past three months as the Health Sciences Authority (HSA) expedites its approval process to meet demand.
These include locally made kits such as the Fortitude test developed by the Agency for Science, Technology and Research (A*Star), as well as tests produced by big-name medical technology companies such as Abbott Laboratories and Roche Diagnostics Asia-Pacific.
All 43 tests have provisional authorisation, meaning that businesses must formally register their tests if they wish to provide them over the longer term.
In a statement on its website, HSA said it has been working with research institutions and companies since the end of January to ensure "the timely availability of good quality performing test kits that are critical during this period of need".
It added that expediting the approval process for such tests has helped expand the number and variety of diagnostic tests available in Singapore.
The kits that have received provisional approval include those for polymerase chain reaction (PCR) tests to pick up traces of the virus, as well as serology tests, which look for antibodies that indicate a person has been infected in the past.
On its website, HSA said it approves tests based on a "risk-calibrated review process", taking into consideration factors such as how the test is designed and supporting validation data.
It also requires companies to submit periodic reports on the safety and performance of these tests.
"If any safety or performance issues are observed, HSA will require relevant follow-up actions at the manufacturer's end," it said.
HSA did not respond to further questions on how many of the approved tests are currently in use.
The issue of testing came under the spotlight after the Ministry of Health (MOH) said 33 confirmed coronavirus cases had turned out to be false positives upon retesting.
The error had arisen because a test kit used on a laboratory machine had not been optimally calibrated. This meant that results were not interpreted correctly.
The laboratory involved conducted these tests between May 5 and May 9. It subsequently stopped testing to recalibrate its test kits and revalidate results.
Earlier this week, MOH's director of medical services Kenneth Mak said advisories will be issued to all laboratories conducting Covid-19 tests to ensure that tests are performed correctly and results are accurate.
In a separate statement on Wednesday night, the ministry said coronavirus tests are conducted at 13 laboratories in Singapore, with facilities at public healthcare institutions accounting for the majority of tests.
Test results - including those from private laboratories - are checked against patients' clinical symptoms and regularly audited, it added.
In response to queries about the testing error, a ministry spokesman said the laboratory involved has switched to another test kit that has been proven to work on the analytical instrument it uses.
"Currently, no other laboratory is using the same test kit and analytical instrument combination," she said.
MOH added that equivocal test results may emerge from time to time. When this happens, laboratories are required to conduct repeat tests with another comparable test kit or request a new sample from the patient.
If the issue cannot be resolved, samples are sent to the National Public Health Laboratory for confirmation.
"As a precautionary measure, public health measures such as contact tracing may be instituted for cases with equivocal results while pending verification, and they are isolated," the ministry said.