Sinovac Vaccine Effective But Lacks Quality Data on Adverse Effects, WHO Says

Sinovac, the COVID-19 vaccine from Sinovac Biotech in Beijing, China, has been declared efficacious in combating COVID-19 in adults by the World Health Organization. Yet, the availability of quality data on risks concerning adverse reactions is insufficient, the international health body further said.

Experts from the WHO's Strategic Advisory Group of Experts (SAGE) studied the vaccine from Phase 3 clinical trials in Turkey, Chile, Brazil, Indonesia, and China.

Sinovac Assessment After Sinopharm Thumbs Down

Results came after WHO SAGE experts expressed "very low confidence" in the data given by state-owned pharmaceutical firm Sinopharm on its COVID-19 vaccine concerning the severe side-effects in a number of patients, Reuters reported.

This new announcement of assessments and data on Sinovac was from SAGE's April 29 meeting, according to a report from the South China Morning Post. This group, however, is not authorized to decide on licensing.

(Photo: Alexandre Schneider/Getty Images)

Sinovac has been used in 32 countries, with over 260 million doses shipped, the SAGE experts noted.

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Of the 35.8 million doses distributed in China, 49 serious adverse events were reported, including cerebral hemorrhage instances. However, it was not clearly stated that those had links to the vaccine.

Sinovac "Efficacious" in Combatting COVID-19

Two doses of Coronavac (or Sinovac) are efficacious in preventing COVID-19 in adults 18 to 57 years old, SAGE declared on the WHO website.

The assessment also cited discrepancies in safety in pregnant women and safety and clinical protection in elderly people, those with existing diseases, and in the appraisal of rare adverse effects spotted after post-authorization safety monitoring.

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SAGE experts noted a "moderate level of confidence" that the risk of serious adverse effects had been low for those aged 59 and below. A "low level of confidence" in the evidence presented that the risk was low for those aged 60 above. It also had a "very low confidence" on data about the risk of severe adverse effects on the same age group.

They also said they have low confidence in the quality of evidence that the risk of serious adverse effects on people with comorbidities would increase the risk for a severe bout with COVID-19 after two jabs of the Sinovac vaccine.

Other WHO technical experts reviewed Sinovac's jab last Wednesday for a potential WHO emergency use listing, a development that would not only allow it for use in the international COVAX sharing platform but also a key international approval for a China-developed vaccine.

WHO Assessment Leaves Serious Questions, Say Experts

Experts not part of the SAGE group say the data that the vaccines seemingly have passed the WHO's standard for efficacy but leaves serious questions, particularly about the efficacy and safety for older adults and high-risk demographics.

They say that the concern lies not in the efficacy of the vaccine but that insufficient data has been provided on the people in these groups to give a statistically stable assessment.