CoronaVac has become the latest vaccine to receive emergency use approval from the World Health Organization (WHO).
Scientists found the vaccine, which is manufactured in China, 51 percent effective at preventing COVID-19 in late-stage trials.
Researchers now say it will play a crucial role in containing the pandemic.
CoronaVac is produced by Sinopharm, the Chinese pharmaceutical company.
At just 54 percent, CoronaVac’s ability to protect the recipient is so far lower than what the seven previously WHO-approved vaccines can provide.
The latest round of trials however suggest that CoronaVac, which is an inactivated-virus vaccine has 100 percent efficacy in preventing severe disease and death.
According to clinical researcher Prof Murat Akova of Turkey’s Hacettepe University, the jab is likely to make a major impact on the global fight to eliminate the existing threat of death and hospitalization due to Covid-19 infection.
“CoronaVac will significantly contribute to the global fight against COVID-19 as a safe and moderately effective SARS-CoV-2 vaccine,” says Prof Akova, who is an expert in infectious diseases at the Ankara institution.
CoronaVac’s approval is the second Chinese vaccine to secure WHO approval, coming on the back of the June 1, 2021 nod granted to Sinovac.
Sinovac is also made in Beijing by the government-run Sinopharm, with a recorded efficacy of 79 percent in protecting people against serious disease and death.
In addition to anchoring the Asian giant’s domestic vaccination campaign, both Chinese vaccines have already been rolled out across the globe, with more than 600 million doses already delivered.
CoronaVac is currently in use in more than 40 countries, including Chile and Botswana. More countries have okayed Sinopharm’s Sinovac vaccine, including Kenya.
Data for the WHO’s efficacy estimates of 51% was obtained from late-stage trials among 9,823 Brazilian medical staff, and posted online as a preprint in April.
Of these, 253 had Covid-19, including 85 in the vaccinated group and 168 among those who received the placebo.
None of the study participants that received the vaccine died or was hospitalized due to COVID-19 infection. Previous smaller studies of late-stage trials in Turkey and Indonesia have recorded efficacy rates at 84 percent.
A study on 2.5 million vaccinated people carried out in Chile after trials indicates a 67 percent efficacy for CoronaVac, according to preliminary findings.
Not only was the shot 67 percent effective at preventing Covid-19, but it also recorded 80 percent effectiveness at preventing death from the disease.
In what could be the most encouraging news, the vaccine showed the effectiveness even when used against the Alpha (B.1.1.7) and Gamma (P.1) variants of the SARS-CoV-2 virus that causes Covid-19.
Preliminary results from The Butantan Institute’s study also showed that Coronavac could stop the deadly advance of the disease through community transmission.
The São Paulo-based institute released the data from trials conducted in the town of Serrana at a press conference on Tuesday.
Findings from the trial that involved almost all the adults in the town are showing that CoronaVac could play a big role in rolling back the pandemic.
Vaccinating people with CoronaVac significantly reduced cases of Covid-19 infection as well as deaths and hospitalizations.
The feat was achieved in spite of the fact that about 4 out of every 10 or 40 percent of the town’s residents were commuting every day to pandemic hot spots.
Butantan Institute’s medical director of clinical research Prof Ricardo Palacios termed CoronaVac’s ability to protect an entire town “remarkable evidence”, adding that this vaccine could be “a game changer in controlling the pandemic”.
Both of the approved Chinese vaccines use established technology based on inactivated virus and can be stored at fridge temperatures.
Easily manageable fridge temperatures has made their transport and storage a relatively affordable affair, as they can easily be administered and stored in resource-poor settings.
The drawback in lower efficacy levels for the Chinese Covid-19 vaccine could be seen in the reduced protection against the disease when compared to mRNA vaccines, such as New York City-based pharmaceutical Pfizer, or the options offered by biotech firms BioNTech operating from Mainz, Germany, and Moderna, located in Cambridge, Massachusetts.
Researchers attribute these differences in protection levels to the technology used to manufacture the various vaccines. In the Chinese case, both the vaccines use a killed or inactive version of SARS-CoV-2 virus to provoke the human body to produce various antibodies against different parts of the viral structure.
Speaking to the Nature scientific journal, Prof Gagandeep Kang, however says that not all of these antibodies are effective at containing the virus.
Prof Kang, a virologist at the Christian Medical College in Vellore, India, works in the Department of Gastrointestinal Sciences and advises the WHO on immunization.
Other vaccine making techniques will lead to more targeted responses against specific virus sections, which is a possible pointer to their higher efficacy.
For instance, by encoding the ‘spike’ protein that SARS-CoV-2 uses to invade cells, the mRNA vacciness can trigger high numbers of antibodies to block that protein.
Since most Covid-19 vaccines are given in two doses, studies to find out whether recipients will need booster shots in future are ongoing.
Scientists says the inactivated-virus vaccine recipients such as those who got CoronaVac and Sinovac jabs could be an area of concern as they produce fewer antibodies.
Prof Kang is still insistent that the important thing to do in the short term is to get as many people as possible vaccinated with their first two doses.
What then, does this crucial WHO emergency approval mean for CoronaVac?
WHO approval now opens the door for the two jabs to become part of the Covid-19 response in low-income countries, through the Covid-19 Vaccines Global Access (COVAX) initiative.
Already, the Vaccine Alliance (Gavi) has expressed its approval of the WHO move to grant CoronaVac the approval.
“Gavi welcomes news that CoronaVac has been granted WHO Emergency Use Listing, as this means the world has yet another safe and effective tool in the fight against this pandemic,” said a Gavi spokesperson in Geneva, Switzerland.
Prior to CoronaVac’s approval, the WHO had also approved the Oxford Astra Zeneca vaccine, as well as its Indian version known as CoviShield that is manufactured by the Serum Institute in Pune, India.
Also approved are the Johnson and Johnson one-shot jab, and the the Moderna and Pfizer–BioNTech vaccines.