China's Sinopharm touts 100% antibody response for COVID-19 vaccine it's already giving to workers

Another day, another Chinese company reports positive early clinical data for a COVID-19 vaccine.

Tuesday, China’s state-run Sinopharm said (Chinese) an inactivated COVID-19 vaccine developed by its subsidiary China National Biotec Group’s (CNBG) Wuhan Institute of Biological Products triggered a strong neutralizing antibody response in a phase 1/2 study.

It appeared to be working best at the middle strength when given 28 days apart, as all participants in that dosing schedule developed neutralizing antibodies that can defend a cell from infection.

As of today, all 1,120 volunteers in the phase 1/2 trial have received two injections of the vaccine at low, middle or high dosing strengths—or placebo—either 14 days, 21 days or 28 days apart, according to CNBG. The seroconversion rate for the 14-day and 21-day schedule of the mid-dose was 97.6%. At 28 days, it was 100%.

The company didn’t specify the neutralizing antibody response rates for the low dose or the high one. It also didn’t elaborate on the exact levels of immune response, only saying the antibody titers were “high.” No serious adverse event was observed.

The vaccine is one of two inactivated shots CNBG is working on. The Wuhan version was pushed into clinical trials April 12, and another developed by its Beijing institute entered human testing in late April. Through two new vaccine production facilities in Beijing and Wuhan, CNBG is aiming to produce 200 million doses of inactivated COVID-19 vaccines a year, according to state news agency Xinhua.

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Now, for the phase 3 efficacy trial, CNBG said it will collaborate with several foreign companies and organizations to run the study abroad. The final stage of the clinical trial is necessary because it’s not yet clear whether neutralizing antibodies are enough to protect a person from COVID-19.

Thing is, the two experimental vaccines from CNBG are already being offered to employees of large state-owned companies who intend to travel overseas, Bloomberg reported last week, citing people familiar with the matter. The offer was relayed by China’s State-owned Assets Supervision and Administration Commission, the government body that oversees these state-run enterprises.

Giving an investigational vaccine to people outside of a clinical trial protocol would be very unusual. But in these uncertain times, travelers' potential exposure to the virus in places where it is still circulating may give researchers an early understanding of the vaccine’s efficacy before a carefully designed phase 3 reads out.

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CNBG’s announcement comes on the heels of Sinovac Biotech’s. On Monday, Nasdaq-listed Sinovac said its inactivated vaccine, called CoronaVac, induced neutralizing antibodies in over 90% of the 600 healthy volunteers in the phase 2 part of a phase 1/2 study.

Before that, another Chinese biotech, CanSino Biologics, unveiled detailed phase 1 data in a recent The Lancet study, demonstrating its adenovirus-vectored recombinant vaccine triggered neutralizing antibodies and T-cell responses.

Right now, five home-grown, clinical-stage COVID-19 vaccines in China are racing against products being developed by Western drugmakers, each hoping to be the first to help relieve countries from lockdowns. The National Institutes of Health now plans to run phase 3 trials of vaccines from Moderna, AstraZeneca and Johnson & Johnson in the coming months. Rather than using a dead strain of the novel coronavirus, those three vaccines are based on the pathogen's genetic materials.