Our business operations could be materially and adversely affected by the COVID-19 pandemic. The COVID-19 pandemic has resulted in the implementation of significant governmental measures, including lockdowns, closures, quarantines, and travel bans, intended to control the spread of the virus. Such governmental actions, together with the further development of the COVID-19 pandemic, could materially disrupt our business and operations, slow down the overall economy, curtail consumer spending, and make it difficult to adequately staff our operations.
Specifically, in response to the COVID-19 pandemic and its spread, the Malaysian government implemented intermittent lockdowns in various stages such as (i) imposing full movement control orders ("MCO"), under which, quarantines, travel restrictions, and the temporary closure of stores and facilities in Malaysia were made mandatory; (ii) easing MCO to a Conditional Movement Control Order ("CMCO") under which most business sectors were allowed to operate under strict rules and Standard Operating Procedures mandated by the government of Malaysia; and (iii) further easing CMCO to Recovery Movement Control Order. On January 12, 2021, due to a resurgence of COVID-19 cases, the Malaysian government declared a state of emergency nationwide to combat COVID-19. On February 16, 2021, the government announced that a National COVID-19 Immunization Plan would be implemented for one year after February 2021, in which 80% of the Malaysian population will be vaccinated to achieve herd immunity. On March 5, 2021, lockdowns in most parts of the country were eased to a CMCO; however, COVID-19 cases in the country continued to rise. On May 12, 2021, the Malaysian government re-imposed a full lockdown order nationwide, until the earlier of when (i) daily COVID-19 infection cases in the country fall below 4,000; (ii) intensive care unit wards start operating at a moderate level; or (iii) 10% of the Malaysian population is fully vaccinated. The total number of COVID-19 cases in the country surpassed three million on February 13, 2022, and the number of daily cases hit a record high of 33,406 on March 5, 2022. Malaysia's COVID-19 restrictions were eased progressively over the course of 2022, with the country eventually reopening its borders and discontinuing the requirement for face masks. On May 5, 2023, the WHO ended the emergency status for COVID-19. However, COVID-19 is still a significant public health problem and will continue to challenge health systems worldwide long term. In December 2023, the Malaysian government reactivated the Heightened Alert System, an early intervention protocol based on the infection and death levels as well as the hospitalization rate, in response to a rise in the number of COVID-19 cases. As of December 28, 2023, an estimated 84.4% of Malaysia's total population had received their second dose of the COVID-19 vaccine, an estimated 50.1% of the total population had received a third dose, and an estimated 2.5% of the total population had received a fourth dose.
In response to efforts to contain the spread of COVID-19, we implemented temporary measures and adjustments of work schemes to allow employees to work from home and collaborate remotely. We also took measures to reduce the impact of the COVID-19 pandemic, including upgrading our telecommuting system, monitoring employees' health on a daily basis, and optimizing the technology system to support potential growth in user traffic.
However, there have been occasional outbreaks of COVID-19 in various cities in Malaysia, and the Malaysian government may again take measures to keep COVID-19 in check. Consumers may have less disposable income and the merchants' advertising budgets may experience a general decline or fluctuate, depending on factors beyond our control, such as the shelter-in-place restrictions due to the COVID-19 pandemic. Substantially all our revenue is concentrated in Malaysia. Consequently, our results of operations will likely be adversely, and may be materially, affected, to the extent that the COVID-19 pandemic or any other epidemic harms the Malaysia and global economy in general. Specifically, prior to April 1, 2022, significant governmental measures implemented by the Malaysian government, including various stages of lockdowns, closures, quarantines, and travel bans, led to the store closure of some of our offline Merchants. As a result, although business in Malaysia had gradually resumed since April 1, 2022, our cash rebate service business was negatively affected to a certain extent, because the number of offline sales transactions between retail shoppers and retail merchants facilitated by us did not grow as much as we expected, leading to a lower amount of cash rebate service revenue than we expected during the fiscal years ended September 30, 2023, 2022, and 2021. However, our digital advertising service revenue was not significantly affected by the COVID-19 pandemic, because more people have opted to use various online services since the beginning of the COVID-19 pandemic. As more advertisers used our digital advertising services through our websites and mobile apps and third-party social media channels to target their audiences, our revenue from digital advertising services increased significantly from fiscal year 2021 to fiscal year 2022. From fiscal year 2022 to fiscal year 2023, the number of advertisers that used our digital advertising services declined from 63 to 31 due to market competition, and our revenue from digital advertising services declined. In addition, any resurgence of the COVID-19 pandemic could negatively affect the execution of customer contracts and the collection of customer payments. The extent to which the COVID-19 pandemic may impact us will depend on future developments, which are highly uncertain and cannot be predicted, including new information on the effectiveness of the mitigation strategies, the duration, spread, severity, and recurrence of COVID-19 and any COVID-19 variants and related travel advisories and restrictions, and the efficacy of COVID-19 vaccines, which may also take an extended period of time to be widely and adequately distributed.