According to the Chinese researchers’ lab study report, antibodies generated by the coronavirus vaccine developed by Sinovac Biotech faded below a critical threshold about half a year after a second dose. In contrast, a third dose strongly boosts immune response. Published on Sunday, researchers reported the findings from blood samples’ study from adults of age 18-59, which hasn’t been peer-reviewed.

Furthermore, the paper stated that for participation in getting two shots, fourteen or twenty-eight days apart, only 16.9 percent 35.2 percent respectively still had a level of neutralizing antibodies above the threshold 180-days after the second shot.

Antibodies triggered by Sinovac Biotech’s #COVID19 vaccine decline below a key threshold from around six months after a second dose for most recipients.

— z.khan (@zakrana) July 26, 2021

The analysis was based on the findings from two cohorts involving over fifty participants each, while the study gave 3rd shot to almost 540 participants. The study showed that when participants in some cohorts were given a 3rd booster shot, nearly 6 months after the second dose, neutralizing antibodies levels after further four weeks had increased about three-five-fold from the levels seen twenty-eight days after the second shot.

3rd Sinovac Dose Provoke More Robust Antibody Response

The analysis was conducted by Chinese researchers at disease control authorities in the Chinese coastal province, Jiangsu, Sinovac Biotech, and other Chinese institutions. Moreover, researchers warned the analysis didn’t test the antibodies’ power against more contagious variants. Also, further study was needed to analyze antibody duration after a third booster dose.

In June, Liu Peicheng, Sinovac spokesman, told Reuters News Agency preliminary outcomes from blood samples taken from the inoculated depicts a threefold decrease in neutralizing response against the more infectious Delta variant and recommended a 3rd Sinovac dose could provoke a more robust antibody response.

Earlier in July, Thailand declared it would use the AstraZeneca-made coronavirus vaccine as the 2nd shot for those who got the first shot of Sinovac Biotech in a bid to boost protection. The decision was first publicly declared mixed vaccine schedule of Western-made shot and a Chinese vaccine, as the latest preliminary Thai research raised worries about the longer-term protection of the two-shot Sinovac Biotech’s vaccine.

That declaration came after the Ministry of Public Health Thailand stated that 618 healthcare workers out of 677348 personnel who received two Sinovac vaccine shots into their arms became infected from April to July 2021. At least one nurse died.

Moreover, neighboring Indonesia has reported breakthrough virus cases among medical and front-line soldiers who are fully vaccinated with the Sinovac Biotech-developed vaccine.