WHO approval of Chinese CoronaVac COVID vaccine will be crucial to curbing pandemic

China’s CoronaVac COVID-19 vaccine is already being used in the Philippines, along with many other countries.Photo credit: Ezra Acayan / Getty

The World Health Organization (WHO) has approved a second Chinese emergency vaccine. CoronaVac was found to be 51% effective in preventing COVID-19 in late-stage studies, and researchers say it will be key to containing the pandemic.

This overall protection is less than that of the seven other vaccines already listed by the WHO. But most importantly, studies suggest that CoronaVac – an inactivated viral vaccine made by Beijing-based Sinovac company – is 100% effective at preventing serious illness and death.

“As a safe and moderately effective SARS-CoV-2 vaccine, CoronaVac will make a significant contribution to the global fight against COVID-19,” says Murat Akova, clinical researcher for infectious diseases at Hacettepe University in Ankara.

Growing importance

CoronaVac was approved on June 1 about a month after the WHO listed another Chinese vaccine, made in Beijing by the state-owned company Sinopharm, which has shown 79% effectiveness against symptomatic diseases. Both vaccines are already in use worldwide and are driving China’s massive internal vaccination campaign.

CoronaVac runs vaccination campaigns in more than 40 countries, including Chile and Botswana. More than 600 million doses have been administered worldwide. Sinopharm’s vaccine is approved in many other countries. But WHO’s emergency approval could now facilitate further distribution of both vaccines to low-income countries through the COVID-19 Vaccines Global Access (COVAX) initiative.

A spokesman for COVAX member Gavi, the Vaccine Alliance, in Geneva, Switzerland, said: “Gavi welcomes the news that [CoronaVac] has received the WHO emergency list as it means that the world has another safe and effective tool in the fight against this pandemic. “

The WHO’s 51% effectiveness estimate was based on data from late-stage studies with health workers in Brazil that were preprinted online1 In April. Of the 9,823 participants included in the analysis, 253 had COVID-19 – 85 in the vaccinated group and 168 among those who received the placebo. None of the vaccinated volunteers were hospitalized or died of COVID-19. Smaller, late-stage studies in Indonesia and Turkey have shown higher efficacy, up to 84%.

Preliminary results from a post-trial study of 2.5 million people in Chile estimated that, despite the presence of the alpha, CoronaVac was 67% effective in preventing COVID-19 and 80% effective in preventing death from the disease ( B.1.1.7.). ) and gamma (P.1) variants of the SARS-CoV-2 virus.

Pandemic game changer

Preliminary results detailed from a trial in the city of Serrana at a press conference in Brazil on Tuesday suggest that CoronaVac could have a significant impact on the pandemic. The Butantane Institute in São Paulo conducted the study in which almost the entire adult population of the city of Serrana was vaccinated with CoronaVac. It found the vaccine significantly reduced cases of COVID-19, hospital admissions, and deaths.

The fact that CoronaVac can protect an entire city despite nearly 40% of the population commuting daily to areas where the pandemic has raged is “remarkable evidence” that this vaccine “could be a turning point in pandemic control”, says study leader Ricardo Palacios, medical director of clinical research at the Butantane Institute.

Both approved Chinese vaccines use an established technology based on inactivated viruses and can be stored at refrigerator temperatures, which makes distribution easier in resource-poor environments – but these type of COVID-19 vaccines appear to offer less protection against the disease than do mRNA – Vaccines such as those made by pharmaceutical company Pfizer in New York City and biotechnology company -BioNTech in Mainz, Germany, and that made by biotech company Moderna in Cambridge, Massachusetts.

Technology challenge

Researchers say this could be due to the technology itself. The vaccines use a killed version of SARS-CoV-2 to induce the human body to make antibodies against many regions of the virus. But only some of these antibodies can effectively deactivate the virus, says Gagandeep Kang, a virologist at Christian Medical College in Vellore, India, who also advises the WHO on vaccinations.

Other platforms trigger more targeted responses against specific parts of the virus, which is why they may be more effective. The mRNA vaccines encode the “spike” protein that SARS-CoV-2 uses to enter cells, causing them to trigger a large number of antibodies that block this protein.

Most COVID-19 vaccines are given in two doses, and studies are being done to assess whether people need a booster dose afterward. This question might be particularly relevant to those who receive inactivated virus vaccines like CoronaVac and Sinopharms vaccine, as they produce fewer antibodies, scientists say. But for now, getting as many people as possible vaccinated with their first two doses should be a priority, says Kang.

The other vaccines that WHO approved for emergency use are the Moderna and Pfizer-BioNTech syringes, as well as those manufactured by Johnson & Johnson and the University of Oxford and AstraZeneca, and a version of the Oxford-AstraZeneca vaccine known as Covishield. which is made by the Serum Institute of India in Pune.

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