Sinovac, the company that produces CoronaVac, did not respond to requests for comment. (Representational)
Amid an aggressive spread of the new COVID-19 strain from the Amazon in Brazil, a recent preliminary study has provided evidence that China's CoronaVac, the country's principal vaccine, might prove ineffective against the coronavirus variant.
According to the Wall Street Journal (WSJ), the small-scale study comes as doctors have warned of a 'humanitarian catastrophe' in Brazil over the coming weeks, with rising deaths and infections overwhelming the hospitals in the country.
The study, which is yet to be peer-reviewed, was designed to test how antibodies created either by vaccination or by previous infections from other versions of COVID-19 respond when faced with the new strain.
Plasma collected from eight people vaccinated five months ago with CoronaVac 'failed to efficiently neutralise' the Amazonian variant of the virus, called P1, according to the study conducted by researchers from Brazil, the UK and the US. While the sample of the study was small and requires further testing, the fact that all eight samples produced the same result is a 'notable phenomenon', opined William de Souza of the University of Sao Paulo in Ribeirao Preto.
Mr De Souza also suggested that the Chinese vaccine is less capable of thwarting P1 infections than versions of the virus previously found in Brazil.
Sinovac, the Chinese company that produces CoronaVac, did not respond to requests for comment, reported WSJ.
Despite having an efficacy rate of around 50 per cent, one of the lowest rates for any existing COVID-19 vaccine, the country has largely relied on CoronaVac since kicking off its immunisation campaign in January, as it accounts for over 70 per cent of vaccine shots in Brazil.
Brazilian president Jair Bolsonaro, a fierce critic of China, had earlier told his supporters that CoronaVac could cause them to die or suffer disabilities. He has instead rooted for hydroxychloroquine and recently the use of an experimental nasal spray to treat COVID-19 patients.
Mr Bolsonaro's administration has been widely criticised for the country's surging death count, highlighting that he had also encouraged people to break Covid rules and had rallied against face masks.
Meanwhile, the P1 strain of the virus is spreading rapidly across Brazil and over 20 other countries, leading to concerns on how well existing COVID-19 vaccines will work against the variant and many other such strains emerging in Brazil.
While other countries have put the worst of the pandemic behind them, public-health specialists are saying that Brazil is facing its darkest days yet, with its daily death count expected to surpass that of the US and reach a new peak in the coming weeks, WSJ reported.
The P1 variant, which first emerged in the Amazonian city of Manaus late last year, is 1.4 to 2.2 times as contagious as versions of the virus previously found in Brazil, and 25 to 61 per cent more capable of reinfecting people, according to a recent study.
Amid the rapid surge of the virus, some hospitals have run out of ICU beds, while some others are operating at near full capacity. Oxygen shortages in hospitals have also led to scores of patients suffocating to death in the Amazon. Some prosecutors even found that intubated patients in the region were tied to their beds following a shortage of sedatives.