VOLUNTARY ANNOUNCEMENT - SARS-CoV-2 mRNA VACCINE (SYS6006) INCLUDED FOR EMERGENCY USE IN CHINA

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement. (Incorpor ated in H ong Kong with limi ted liabi lity) (Stock co de: 1093) VOLUNTARY ANNOUNCEMENT SARS-CoV-2 mRNA VACCINE（SYS6006） INCLUDED FOR EMERGENCY USE IN CHINA The board of directors (the “Board”) of CSPC Pharmaceutical Group Limited (the “Company”, together with its subsidiaries, the “Group”) is pleased to announce that, as proposed by the National Health Commission of the People’s Republic of China and approved by the National Medical Products Administration (the “NMPA”) after assessment, the Group’s COVID-19 mRNA vaccine (SYS6006) (the “Product”) has been included for emergency use in China for the prevention of COVID-19 caused by the infection of SARS-CoV-2. SYS6006 is a mRNA vaccine independently developed by the Group, covering Omicron subvariant BA.5’s coremutation atthespike mutation positions. Itwasgranted emergency clinical trial approval by the NMPA in April 2022, and has completed Phase I, II and heterologous booster vaccination clinical studies in China with over 5,500 participants. The results have demonstrated its safety, immunogenicity and efficacy. The incidence of adverse events in SYS6006 was low, with the most common adverse events being grade 1and grade 2fever and injection site pain. The incidence of adverse events were substantially lower in the elderly group compared to the adult group, providing a better risk-benefit ratio in the elderly population. Thegeometric mean titer (GMT) ofneutralising antibodies against Omicron BA.5 14 days after one dose of SYS6006 booster was 236, which is 83 times higher than that before the booster vaccination. One booster dose of SYS6006 has shown good cross-neutralisation against Omicron BA.5,BF.7,BQ.1.1, XBB.1.5 andCH.1.1 strains intheparticipants whohadreceived 2or3 doses of inactivated vaccine. Results of the clinical studies have shown that SYS6006 consistently - 1 - induces specific T-cell immunity against wild-type, Delta, Omicron BA.2 and BA.5 strains in both primary and heterologous booster vaccination, with the immunity maintaining at high levels for an extended period and the cellular immune response against different strains approximately the same. In a heterologous booster clinical study (study no.: SYS6006-008) of 4,000 participants conducted during the pandemic (from 10 December 2022 to 18 January 2023), using a recombinant protein vaccine as control, the efficacy of SYS6006 observed was 70.2% (95% CI: 53.6% – 80.9%) 7 to 28 days after booster vaccination; the efficacy of SYS6006 observed was 85.3% (95% CI: 56.9% – 95.0%) 14 to 28 days after booster vaccination. The Product adopts advanced technology with independent intellectual property rights, with the advantages of achieving higher production capacity, better process reproducibility, large-scale production and scale-up more easily. It has good consistency of product quality, all batches of samples sent to National Institutes for Food and Drug Control have passed the test results. The Product is stable and can be stored at 2-8°C for a long time. The Product is the first independently developed mRNA vaccine product in China that has been granted for emergency use, demonstrating the research and development capabilities of the Group’s nucleic acidplatform. TheGroupwillfullyconsider thecurrent mutation characteristics oftheSARS- CoV-2 virus, predict the mutation trend of future strains, promote the development of new generations of SARS-CoV-2 mRNA vaccines against mutated strains, and actively promote the development progress of other products on the platform. By order of the Board CSPC Pharmaceutical Group Limited Cai Dongchen Chairman Hong Kong, 22 March 2023 As at the date of this announcement, the Board comprises Mr. CAI Dongchen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. PAN Weidong, Mr. WANG Huaiyu, Dr. LI Chunlei, Dr. WANG Qingxi, Mr. CHAK Kin Man and Dr. JIANG Hao as executive directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, Mr. LAW Cheuk Kin Stephen and Ms. LI Quan as independent non-executive directors. - 2 -

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