CoronaVac, the Chinese vaccine developed by Sinovac, offers 83.5% protection against symptomatic COVID-19, according to interim data from a Phase 3 trial in Turkey published in the Lancet on Friday. 

Meanwhile, a large study of the efficacy of the vaccine on 10.2 million Chileans found that it was 65.9% effective in preventing infection, 87,5% effective in preventing hospitalisation and 86% effective in preventing death after two doses, according to a report published in the New England Journal of Medicine on Thursday.

In a study involving 10.2 million participants in Chile, the effectiveness of an inactivated, China-developed #SARSCoV2 vaccine was estimated. Effectiveness was 65.9% for infection, 87.5% for hospitalization, 90.3% for ICU admission, and 86.3% for death.

— NEJM (@NEJM) July 7, 2021

CoronaVac – which can be stored and transported at normal fridge temperature – has been approved for emergency use in 22 countries, and by the World Health Organization (WHO).

The Turkish trial involved over 10,000 people, 6,650 of whom received two doses of the vaccine 14 days apart, while 3,568 received a placebo.

During the trial, 150 COVID-19 cases were confirmed – nine in the vaccine group (an incidence rate of 32 cases per 1,000 people per year) and 32 in the placebo group (an incidence rate of 192 cases per 1,000 people). Following analysis, the authors estimate that this is equivalent to a vaccine efficacy of 83.5%. 

CoronaVac induced an antibody response among 90% of those who received the vaccine, but the response decreased with age. 

No Freezing Necessary

No severe adverse events or deaths were reported and most adverse events were mild and occurred within seven days of an injection, according to the data.

“In order to bring the COVID-19 pandemic under control, the world needs every single dose of safe and effective vaccines, and our results add important evidence of the safety and effectiveness of inactivated-virus vaccines,” said lead author Professor Murat Akova, from Hacettepe University Medical School in Turkey. 

“One of the advantages of CoronaVac is that it does not need to be frozen, making it easier to transport and distribute. This could be particularly important for global distribution, as some countries may struggle to store large amounts of vaccine at very low temperatures.”

However, the Lancet noted that “more research is needed to confirm vaccine efficacy in the long term, in a more diverse group of participants, and against emerging variants of concern”. The majority of Turkish participants (58%) were men, the average age was 45 and all participants were between 18 and 59.

Earlier, Health Policy Watch reported on worrying indications that the Chinese Sinopharm and Sinovac COVID vaccines used by the hundreds of millions to vaccine-strapped low- and middle-income countries may not be performing as well as expected.

Earlier in the week, news outlet CNBC reported that five of the six highly vaccinated countries experiencing surges had used CoronaVac.

The Chilean observational study is the first to consider data from a mass vaccination rollout of CoronaVac.

“Estimates of vaccine effectiveness in the prevention of Covid-19 are essential because they reflect real-world challenges, such as logistics, cold chains, vaccination schedules, and follow-up, and also involve more diverse populations than those selected in randomized clinical trials, such as older or immunocompromised persons or those with coexisting conditions,” according to the NEJM.

“Despite being the standard for assessing vaccine efficacy, phase 3 clinical trials have some limitations, such as restrictive inclusion criteria and implementation under strict experimental conditions that may not resemble a mass vaccination rollout,” it added.

Using data from the national health system, which treats 80% of the population, the Chilean study estimated vaccine effectiveness based on laboratory-confirmed COVID-19, hospitalization, admission to the ICU, and death. 

Image Credits: Twitter – Chinese Embassy Manila.