sinovac vaccine

 by: Nia Amira Najwa binti Azmi

Sinovac as well as another China-made vaccine, Sinopharm, have received emergency use authorisation by the World Health Organization (WHO). Sinopharm is also classified under the inactivated virus vaccine category.

SAGE recommends the use of Sinovac-CoronaVac vaccine as 2 doses (0.5 ml) given intramuscularly. WHO recommends an interval of 2–4 weeks between the first and second dose. It is recommended that all vaccinated individuals receive two doses.

If the second dose is administered less than 2 weeks after the first, the dose does not need to be repeated. If administration of the second dose is delayed beyond 4 weeks, it should be given at the earliest possible opportunity.

How efficacious is the vaccine?

A large phase 3 trial in Brazil showed that two doses, administered at an interval of 14 days, had an efficacy of 51% against symptomatic SARS-CoV-2 infection, 100% against severe COVID-19, and 100% against hospitalization starting 14 days after receiving the second dose.

Does it work against new variants of SARS-CoV-2 virus?

In an observational study, the estimated effectiveness of Sinovac-CoronaVac in health workers in Manaus, Brazil, where P.1 accounted for 75% of SARS-CoV-2 samples was 49.6% against symptomatic infection (4). Effectiveness has also been shown in an observational study in Sao Paulo in the presence of P1 circulation (83% of samples).

Assessments in settings where the P.2 Variant of Concern was widely circulating – also in Brazil - estimated vaccine effectiveness of 49.6% following at least one dose and demonstrated 50.7% two weeks after the second dose. As new data becomes available, WHO will update recommendations accordingly. 

SAGE currently recommends using this vaccine, according to the WHO Prioritization Roadmap.

Does it prevent infection and transmission?

There is currently no substantive data available related to the impact of COVID-19 vaccine Sinovac-CoronaVac on transmission of SARS-CoV-2, the virus that causes COVID-19 disease.

In the meantime, WHO reminds of the need to stay the course and continue practising public health and social measures that should be used as a comprehensive approach to prevent infection and transmission. These measures include wearing a mask, physical distancing, handwashing, respiratory and cough hygiene, avoiding crowds and ensuring adequate ventilation according to local national advice.