Taiwan's President Tsai Ing-wen received her first shot of the island's homegrown Covid-19 vaccine on Monday, a public show of support for the new drug which is central to plans for inoculation self-sufficiency amid low immunization rates and struggles to obtain vaccines from overseas.

Monday's island-wide rollout of the Medigen Covid-19 vaccine, developed by Taipei-based Medigen Vaccine Biologics Corporation, comes after the drug was approved for emergency use last month by Taiwanese authorities for anyone above 20 years old, with at least 28 days between the two doses.

The vaccine has yet to complete phase 3 clinical trials and no efficacy data is available.

Paul Torkehagen, Medigen's director of overseas business development, told CNN in May that the company designed a "very large" phase 2 clinical trial to ensure the vaccine's safety and effectiveness, with 3,800 participants. Normally, a stage 2 clinical trial only involves several hundred people.

Data from the trials showed that 99.8% of participants were able to form antibodies against Covid-19 after taking two doses of the vaccine, Medigen's CEO Charles Chen said.

Taiwan's Centers for Disease Control said in a July 19 statement that the vaccine posed no serious health effects.

Taiwan has ordered 5 million doses of the vaccine from Medigen and more than 700,000 people have already signed up to receive it, according to Reuters.

In a Facebook post after receiving the vaccine at a hospital in Taipei, Tsai said she hadn't suffered from any post-vaccination pain and thanked the health care workers who had administered the shot.

"Taking the vaccine can protect yourself, your family, as well as medical staff," Tsai wrote. "Let's do our part in boosting Taiwan's collective defense against the virus!"

With its borders sealed to most travellers and strict measures enacted to contain local outbreaks, Taiwan has so far been largely successful in containing Covid-19, reporting fewer than 16,000 total confirmed infections and 828 deaths. But the island has struggled to vaccinate its more than 23 million population, partly due to difficulties obtaining doses from international suppliers.

Taiwan's government has only managed to import around 10 million Covid-19 vaccines, according to Reuters. In July it ordered another 36 million doses of the Moderna shot.

Fewer than 5% of Taiwan's population has received both doses of their Covid-19 vaccine, according to Reuters, as the island delays second dose vaccinations so more people can receive a first shot.

On Monday, Taiwan reported four new Covid-19 cases, according to the Central Epidemic Command Center (CECC). Authorities announced on the weekend they would ease virus prevention measures to allow for larger gatherings and the opening of study centers and indoor amusement parks.

But Health and Welfare Minister Chen Shih-chung said current Covid-19 restrictions -- which include the closure of bars and nightclubs -- would remain in place until at least September 6, with the possibility of an extension if the global outbreak continued to grow.

Taiwan could become increasingly isolated if it keeps pursuing its "Covid zero" strategy, with both Australia and New Zealand hinting they might abandon the approach once vaccinations reach a certain level.

In an opinion piece published on Sunday, Australian Prime Minister Scott Morrison said that while lockdowns to prevent Covid-19 transmission were "sadly necessary for now," they may not be once vaccination rates increased to the targets of 70% and 80%.

"This is what living with Covid is all about. The case numbers will likely rise when we soon begin to open up. That is inevitable," he said.

In neighbouring New Zealand, which has also attempted to eliminate the virus within its borders, Covid-19 response minister Chris Hipkins told local media the highly contagious Delta variant raised "some pretty big questions about what the long-term future of our plans are."

"At some point we will have to start to be more open in the future," he said.