The Health Sciences Authority (HSA) granted an interim authorisation yesterday under the Pandemic Special Access Route (PSAR) for Sinovac-CoronaVac, an inactivated SARS-CoV-2 vaccine developed by Sinovac Biotech, to be used for the prevention of COVID-19 in individuals aged 18 years and above. The application is for a vaccination regime that requires two doses of the vaccine to be administered 28 days apart.
Review of data from Sinovac
Sinovac Biotech had submitted the PSAR application to HSA in December 2020, and HSA requested for more manufacturing and clinical data from the company. They subsequently submitted clarifications in July and August 2021 to supplement the initial data following HSA’s queries.
Besides conducting a careful and thorough review of the additional data, HSA took into consideration the current COVID-19 public health emergency and taking into account the public health needs in Singapore of having non-mRNA vaccines as an option to individuals who are medically unsuitable to receive mRNA vaccines.
Experts from HSA’s Medicines Advisory Committee and Panel of Infectious Diseases Experts were consulted in reaching the decision for interim authorisation for the vaccines under PSAR.
Vaccine efficacy
HSA’s clinical review was based primarily on the data from the Phase III study conducted in Brazil which demonstrated vaccine efficacy¹ of 51% against non-Delta variants, which meets the threshold of 50% set by the World Health Organisation (WHO) for Emergency Use Listing (EUL)². This means that there is a 51% reduction of symptomatic COVID-19 disease in a vaccinated group of people as compared to a similarly sized group of unvaccinated people.
HSA also reviewed data from pre-clinical studies, clinical trials in human volunteers, manufacturing and quality controls, as well as supplemental data from a real-world effectiveness study in Chile which involved over 10 million participants aged 16 years and above. At the data cut-off in May 2021, Sinovac-CoronaVac demonstrated vaccine effectiveness of 66% against the Alpha and Gamma variants. The Chile study also showed that the vaccine offered more than 86% protection against other COVID-19 disease outcomes such as hospitalisation, admission to ICU and death.
The company did not submit data on the vaccine’s protection against the Delta variant. The vaccine efficacy / effectiveness in persons with co-morbidities such as diabetes, cardiovascular diseases, cancers, as well as in immunocompromised patients, remains inconclusive as there was insufficient data in these subpopulations in both the clinical trial and real-world study. There was also a lack of data in older adults aged 60 years and above in the Phase III clinical trial in Brazil. Nonetheless, HSA took into consideration the supplemental evidence from the Chile study which showed that the effectiveness in the older population was consistent with that observed in the overall population. Based on this data, HSA is currently not setting any upper age limit for the use of Sinovac-CoronaVac.
When considering the use of the vaccine, doctors should carefully assess the benefit-risk of using Sinovac-CoronaVac for the specific individual and follow the recommendations of MOH’s Expert Committee on COVID-19 Vaccination. Doctors should also inform the individual of the documented clinical efficacy of the vaccine.
Vaccine safety
Based on the data, HSA has determined that the safety profile of Sinovac-CoronaVac was generally consistent with other registered vaccines used in immunisation against other diseases. HSA has also advised that as with all vaccines, there will be a small proportion of susceptible persons who experience severe allergic reactions upon vaccinations. In such cases, immediate medical attention should be sought.
As there was insufficient data on the use of Sinovac-CoronaVac in pregnant women, severely immunocompromised persons, persons with co-morbidities and those under the age of 18, no recommendations can be made by HSA for use in these sub-populations.
HSA will continue to actively review evolving vaccine effectiveness and safety data to ensure that the benefits of the vaccine continue to outweigh the known risks. The PSAR interim authorisation may also be terminated at any time; for example, if new data suggests that the benefits no longer outweigh the risks.
¹Vaccine efficacy is the degree to which a vaccine prevents a disease under controlled conditions in a clinical trial.
²https://www.who.int/publications/m/item/who-target-product-profiles-for-covid-19-vaccines
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