Factbox: Development of Sinovac's potential coronavirus vaccine

(Reuters) - A COVID-19 vaccine developed by China’s Sinovac Biotech is 78% effective based on late-stage trial results in Brazil, a source said on Thursday, moving it a step closer to regulatory approval in South America’s biggest country.

FILE PHOTO: Glass bottles are seen at the bottling section where the Coronavac, SinoVac's vaccine against the coronavirus disease (COVID-19), will be produced at Brazil's biomedical center Butantan Institute in Sao Paulo, Brazil December 22, 2020. REUTERS/Amanda Perobelli

Already approved for emergency use in China, the CoronaVac vaccine is also being considered for mass inoculation in developing countries including Indonesia, Brazil and Turkey.

Below are the main details of Sinovac vaccine.


* CoronaVac uses an inactivated, or dead, version of a coronavirus strain that was isolated from a patient in China. It is chemically prevented from replicating in human cells, but will trigger an immune response.


* It’s a two-dose regimen administered at a two-week interval.

* But early stage trials showed a four-week interval induced the strongest antibody response, and researchers have said giving two doses with a one-month interval might be more appropriate when the risk of the pandemic eases.

* The vaccine can be stored at normal refrigerated conditions of 2 to 8 degrees Celsius (36°-46°F) and may remain stable for up to three years, its researchers said in November.


* There was one case of a severe allergic reaction within 48 hours of receiving the first shot in the early stage of trials, which might be related to vaccination. The subject recovered within three days and did not experience a similar reaction after the second dose.

* The most common symptom reported during early trials was pain at the injection site.

* Experts caution that the safety of inactivated coronavirus vaccine candidates should be observed over longer periods, as some other inactivated vaccines have led to disease enhancement effect, where vaccine-triggered antibodies, instead of offering protection, worsen infections when people become exposed to the viruses after inoculation.


* Phase I/II trials began in April and were carried out in Suining County of Jiangsu province in China, involving about 740 volunteers. All participants were aged 18 to 59 years with no history of COVID-19 infection.

* Early trials showed that CoronaVac induces a quick immune response but the level of antibodies produced is lower than in people who had recovered from the disease.

* Sinovac also tested the vaccine on 421 elderly volunteers aged 60 to 89 with a 28-day immunisation interval, which showed a positive immune response.

* Sinovac is also running a Phase I/II trial in healthy children and adolescents aged 3-17 years.


* Phase III trials are under way in Brazil, with more than 13,000 participants, Indonesia (more than 1,600), Turkey (around 13,000) and Chile (2,300).

* Sinovac is also seeking a late-stage trial in the Philippines.


* Indonesia has a deal to buy 125.5 million doses, and 3 million doses have already arrived in the country.

* Brazil’s Butantan Institute biomedical centre expects to have 46 million doses of the vaccine ready in January to be used, if it is approved by the country’s health regulator Anvisa.

* Chile has a deal to buy 60 million doses, Turkey agreed to 50 million doses, and Ukraine signed a contract to buy 1.8 million doses. [nL1N2J4138]

* Singapore signed a deal for undisclosed amount, while Malaysia and the Philippine are in talks with Sinovac.

* Thailand will take delivery of 200,000 doses of Sinovac’s vaccine by February.

* Sinovac would be able to manufacture 300 million doses annually, and completion of a second production facility would double its capacity to 600 million doses, it said on Dec 7.

Reporting by Miyoung Kim and Roxanne Liu. Editing by Gerry Doyle, Josephine Mason and Giles Elgood