Between 2021 and 2022, 453 people who had received their first dose of a Covid vaccine were recruited and randomly assigned to receive either SIM01 or a placebo.

Reports of adverse effects one month after receiving a second Covid jab was significantly lower among the SIM01 group.

The study continued for 11 more months with consistent results, ending with 5.4 percent and 14.4 percent of people reporting adverse effects in the SIM01 and placebo groups, respectively. Additionally, the SIM01 group reported improvements in sleep quality, mood and skin conditions.

Zhang Lin, assistant professor at the Department of Medicine and Therapeutics, said a next-generation shotgun sequencing technology was used to evaluate the effectiveness of SIM01.

Medical faculty dean Francis Chan Ka-leung said: "This study demonstrates Hong Kong's ability to translate scientific findings into tangible innovations."

Meanwhile, the government's Indemnity Fund for Adverse Events Following Immunization with Coronavirus Disease-2019 Vaccines in September paid a sum of HK$5.4 million in compensation to 22 people with adverse post-vaccination effects.

The fund has so far disbursed HK$2 million for a fatality and HK$65 million for 342 injury cases since its introduction last June.