CLOVER BIO-B - Voluntary Announcement Clover Announces Positive Australia Phase 2 Clinical Data for RSV + hMPV + PIV3 Respiratory Combination Vaccine Candidates in Older Adults

VOLUNTARY ANNOUNCEMENT

CLOVER ANNOUNCES POSITIVE AUSTRALIA PHASE 2 CLINICAL DATA

FOR RSV + hMPV ± PIV3 RESPIRATORY COMBINATION VACCINE CANDIDATES

IN OLDER ADULTS

This announcement is made by the board (the "Board") of directors (the "Directors") of Clover Biopharmaceuticals, Ltd. (the "Company" or "Clover", together with its subsidiaries, the "Group") on a voluntary basis to inform the shareholders of the Company and potential investors on the latest business development of the Group.

The Company is pleased to announce positive preliminary data from a Phase 2 clinical trial in older adults in Australia evaluating SCB-1022 (RSV + hMPV) and SCB-1033 (RSV + hMPV + PIV3) protein-based vaccine candidates based on prefusion-stabilized F (PreF)-Trimer subunit vaccine antigens utilizing Clover's validated Trimer-Tag vaccine technology platform.

The ongoing Phase 2 trial for Clover's combination vaccine candidates is a randomized, observer-blinded, multicenter study with 420 older adults (60-85 years) enrolled in Australia, and the participants have been randomized to receive either SCB-1022 (RSV + hMPV), SCB-1033 (RSV + hMPV + PIV3) or placebo.

Immunogenicity

• Antibody titers (geometric mean titers [GMTs]) at 28 days post-vaccination in the Phase 2 were generally in-line with or trended higher than the prior Phase 1 trial.

• Geometric mean fold rises (GMFRs) in neutralizing antibodies (nAbs) at 28 days post-vaccination compared to pre-vaccination:

o RSV nAbs: Approximately 6-9 fold increases

o hMPV nAbs: Approximately 6-8 fold increases

o PIV3 nAbs: Greater than 3-fold increase (approximately 5 fold increase in participants with baseline PIV3 nAbs in the bottom tertile), driven by up to approximately 20 fold increases in PIV3

PreF-specific antibodies1

• No drop-off in antibody responses observed in the oldest participants (75+ years) compared to younger

participants (60-74 years).

• No signs of immune interference on RSV and hMPV nAbs from the addition of PIV3 PreF antigen in

SCB-1033 (RSV+hMPV+PIV3) compared to SCB-1022 (RSV+hMPV).

Respiratory Tract Infections (Based on AE Reporting):

• Approximately 62% lower rate of respiratory tract infection was observed in the vaccine groups (SCB- 1022 and SCB-1033) versus the placebo group within 28 days of vaccination based on AE reporting of

any respiratory tract infections (no PCR sequencing of infection cases was conducted in the study).

• Significant RSV outbreak2 with co-circulation3 of hMPV and PIV in Australia occurred during the study

enrollment and follow-up period.

Safety and Reactogenicity

• SCB-1022 and SCB-1033 were generally well-tolerated; solicited local and systemic adverse events (AEs) within 7 days of vaccination were mostly mild and all transient.

o The most common solicited AEs were fatigue, headache and injection site pain, with mean durations of approximately 2 days for the vaccine groups (SCB-1022 and SCB-1033) and the

placebo group.

• The frequency of unsolicited AEs within 28 days of vaccination was similar across the vaccine and

placebo groups.

• There were no vaccine-related serious adverse events (SAEs), AEs of special interest (AESIs), or AEs

leading to discontinuation.

Commercial-Scale Manufacturing Scale-Up:

• In parallel with the Phase 2 trial, Clover conducted commercial-scale 2,000L bioreactor scale-up production of multiple batches of Trimer-Tagged RSV, hMPV and PIV3 PreF antigen components of

SCB-1022/1033.

• The successful 2,000L production process scale-up further de-risks future late-stage development and

commercialization.

Based on these positive Phase 2 results for the RSV + hMPV ± PIV3 combination vaccine candidates further validating the Trimer-Tag platform, Clover will continue to evaluate continued mid- and late-stage development plans as well as potential global collaboration opportunities for value maximization.

Notes:

1. PIV3 PreF-specific nAbs (such as Site Ø and Site X) can potently neutralize the PIV3 virus (DOI: 10.1038/s41467-023-36459-3) , but unlike RSV and hMPV, the majority of pre-existing PIV3 nAbs at baseline are against the PIV3 HN protein (whereas levels of pre-existing PIV3 nAbs against the PIV3 PreF protein at baseline are low) (DOI: 10.1038/s41564-024-01722-w). Therefore, a numerically lower increase in total PIV3 nAbs induced by SCB-1033 (containing PIV3 PreF antigen) – as compared to increases in RSV and hMPV nAbs – is expected.

2. Australia Immunisation Coalition (Aus. Gov. Department of Health, National Notifiable Diseases Surveillance System). January-May 2026.

3. Australia CDC. % of severe ARI (acute respiratory infection) cases sent to a sentinel intensive care. January- May 2026.

Shareholders of the Company and potential investors are advised to exercise caution when dealing in the shares of the Company.

By order of the Board

Clover Biopharmaceuticals, Ltd. Dr. Peng LIANG

Chairman of the Board

Shanghai, PRC, September 7, 2026

As of the date of this announcement, the Board comprises Dr. Peng LIANG and Mr. Joshua G LIANG as executive Directors; Dr. Xiaodong WANG and Dr. Donna Marie AMBROSINO as non-executive Directors; and Dr. Xiaobin WU, Mr. Xiang LIAO, Mr. Jeffrey FARROW and Mr. Thomas LEGGETT as independent non-executive Directors.