GENEVA: The COVID-19 vaccine produced by China's Sinovac Biotech is efficacious in preventing COVID-19 in adults under 60, but some quality data on the risk of serious adverse effects is lacking, World Health Organization experts have found.
The independent experts on the WHO's Strategic Advisory Group of Experts (SAGE) reviewed Sinovac's CoronaVac jab from phase 3 clinical trials in China, Brazil, Indonesia, Turkey and Chile.
The assessment came shortly after WHO SAGE experts had voiced "very low confidence" in data provided by Chinese state-owned drugmaker Sinopharm on its COVID-19 vaccine regarding the risk of serious side-effects in some patients, but overall confidence in its ability to prevent the disease, a document seen by Reuters showed.
The Sinovac vaccine has been authorised in 32 countries and jurisdictions, with 260 million doses distributed, the SAGE experts said.
"We are very confident that 2 doses of CoronaVac are efficacious in preventing PCR confirmed COVID19 in adults (18-59 years)," SAGE said in an assessment posted on the WHO website.
It cited evidence gaps in safety in pregnancy, and on safety and clinical protection in older adults, those with underlying disease, and evaluation of rare adverse events detected through post-authorization safety monitoring.
The experts said they had a "moderate level of confidence" that the risk of serious adverse effects was low in people aged 59 and less, but had a "low level of confidence" in the quality of evidence that such risk was also low for adults above 60.
"We have low confidence in the quality of evidence that the risk of serious adverse events in individuals with comorbidities or health states that increase risk for severe COVID-19 following one or two doses of CoronaVac is low," they added.
A separate group of WHO technical experts was reviewing Sinovac's shot on Wednesday for possible WHO emergency use listing - which would not only pave the way for its use in the global COVAX vaccine sharing platform but also provide a crucial international endorsement for a vaccine developed in China.