Global Phase III Clinical Trial on Recombinant Two-Component COVID-19 Vaccine (CHO Cell) in Nepal

SOLID Nepal is conducting its second vaccine trial in Nepal, entitled "A multicenter, randomized, double-blinded, placebo-controlled phase III trial to evaluate the efficacy, safety, and immunogenicity of the recombinant two-component COVID-19 vaccine (CHO cell) in adults aged 18 years and older."

Notably, the vaccine's Phase I trial took place in New Zealand, followed by Phase II trials in the Philippines and the United Arab Emirates. The findings from Phase II trials revealed that individuals who received the CHO cells sequential booster after basic immunization with an inactivated vaccine exhibited higher levels of neutralizing antibodies against the Omicron variants BA.5, BA.2, BF.7, and BA.2.75 compared to those who received Pfizer’s mRNA vaccine, showing significant statistical differences.

Phase III Trial Execution in Nepal

In Nepal, the Phase III trial was executed across three key sites. The first site, B.P. Koirala Institute of Health Sciences in Dharan, vaccinated 2,097 participants. The Provincial Hospital in Bhadrapur, the second site, vaccinated 1,504 participants, while the third site, Manmohan Institute of Health Sciences in Dahachowk, vaccinated 1,006 participants. The total enrollment across these three sites in Nepal reached 4,607 individuals, all of whom completed the three doses of the vaccine and specified follow-up visits as outlined in the protocol.

Participant Eligibility and Vaccination Schedule

For the vaccination, participants who had not received any COVID-19 vaccination and had no known COVID-19 infection in the previous six months were eligible. A three-dose intramuscular (IM) vaccination schedule, with a 21-day interval, was applied. Notably, participants aged 60 and above constituted approximately 15% of the cohort. Those with negative SARS-CoV-2 antibody (IgM and IgG) levels at baseline were randomized in a 1:1 ratio to receive either CHO cell (20 μg) or a placebo on Day 0, Day 21, and Day 42, with participants stratified by age (18-59 years, ≥ 60 years) and study sites.

Endpoints and Outcomes

The primary endpoint of the trial is RT-PCR confirmed symptomatic COVID-19 cases (regardless of severity) that occurred more than 14 days after the three doses of vaccination. The secondary endpoint includes cases that occurred more than 14 days after the first dose of vaccination. Nepal reported a total of 210 endpoint cases, encompassing both primary and secondary cases.

This trial represents a crucial advancement in the ongoing efforts to combat the COVID-19 pandemic and aims to provide valuable insights into vaccine efficacy and safety for communities worldwide.