WHO Interim Guidelines on Sinovac (Abridged version) / แนวทางการใช้วัคซีนซิโนแวคขององค์การอนามัยโลก ระหว่างรอฉบับสมบูรณ์ (ฉบับย่อ)

Based on clinical trials in Brazil, Indonesia and Turkey, the efficacy of two doses of Sinovac against symptomatic infection ranged from 51% to 83%. In clinical trial in Brazil, efficacy against severe disease and hospitalizations was 100%, 14 days after the second vaccination. Based on post-vaccine introduction studies in Chile, the effectiveness of Sinovac to prevent symptomatic disease, hospitalization, and death was 67%, 85% and 80%, respectively.  

Two doses of vaccination are needed with an interval of 2-4 weeks.   If administration of the second dose is delayed beyond 4 weeks, it should be given at the earliest possible opportunity. 

Adults aged 18 years and above can be given Sinovac. Due to limited supply, vaccination should be first offered to those who are most at risk of infection or severe disease and death; this group includes health workers, elderly and those with comorbidities.  

Due to limited data for elderly population, the vaccine efficacy could not be determined from the clinical trials. Post-vaccine introduction studies from Chile demonstrated that among the elderly population,  vaccine effectiveness 14 days after dose 2 doses was 67% against symptomatic infection, 83%  against hospitalisations, and 83% against death. The currently available clinical trial and data from mass vaccination indicate that the vaccine is safe in older adults. Elderly are at high risk of severe disease and death due to COVID-19 and are identified as a priority group for vaccination. Based on all currently available evidence, WHO recommends the vaccine for use in persons aged 60 years and older. 

Evidence suggests that pregnant women with COVID-19 are at higher risk of developing severe disease compared to non-pregnant women of reproductive age. COVID-19 in pregnancy has also been associated with an increased risk of preterm birth and of neonates requiring intensive care. Pregnant women who are aged 35 years or older, or who have high body mass index or an existing comorbidity, such as diabetes or hypertension, are at particular risk of serious outcomes from COVID-19.  Sinovac is an inactivated vaccine with an adjuvant that is routinely used in many other vaccines with a documented good safety profile, including in pregnant women. On the basis of previous experience with use of other inactivated vaccines used during pregnancy, the effectiveness of Sinovac in pregnant women is expected to be comparable to that observed in non-pregnant women of similar age. WHO recommends the use of Sinovac in pregnant women when the benefits of vaccination to the pregnant woman outweigh the potential risks.

Currently, there are no clinical trial data to assess efficacy of Sinovac against variants. Based on post-vaccine introduction data in countries where variants are circulating, Sinovac has high effectiveness in preventing severe disease, hospitalisations and death.  WHO currently recommends the use of Sinovac to priority groups  even if variants are present in the country.