SINGAPORE: Most Southeast Asian stock markets slipped on Wednesday, tracking overnight losses on Wall Street, as investors refrained from making big bets after doubts were cast over a recent early-stage trial of a coronavirus vaccine.

Data from a small, early-stage safety trial testing Moderna Inc's experimental COVID-19 vaccine does not provide the critical data needed to assess its effectiveness, health-focused Stat News reported on Tuesday, citing experts.

"Asian markets may retreat on Wednesday after a setback in vaccine optimism with investors refocusing on the downbeat economic outlook induced by COVID-19," economists at ING said in a note.

Leading losses in Southeast Asia, Singapore's Straits Times Index snapped three sessions of gains and fell 1%, with industrial stocks weighing the most, even as the city-state looks to restart its economy with a phased easing of restrictions.

Singapore Airlines and conglomerate Jardine Matheson Holdings shed as much as 3.2% and 2.7%, respectively. ING economists, however, said Singapore's economy would take a long time to recover as a gradual three-phase reboot will not be completed for several months more at least.

In Indonesia, the benchmark edged lower as capital Jakarta extended coronavirus-related curbs until June 4. The index is set to snap two straight sessions of gains. Pollux Properti Indonesia slid 6.9%, while PT Bank Tabungan Pensiunan Nasional Syariah lost 4.6%.

Malaysian shares ticked lower after gaining for five sessions, ahead of April inflation data.

Thai stocks inched 0.5% higher, ahead of the country's central bank's meeting. The Bank of Thailand is widely expected to cut interest rates by another 25 basis points, bringing the policy rate down to 0.5%.

"However, with growth already in negative territory... don't be surprised if we see a bigger, 50bp rate cut today," ING economists said. Vietnam shares found solace in a potential free trade agreement with the European Union (EU), and edged higher.

The World Bank said the trade pact with EU set to soon be ratified by Vietnam should boost the Asian nation's economic recovery from the coronavirus pandemic. - Reuters