China’s Covid-19 vaccine only 50% effective, Brazil’s results show
Far lower than the 78% originally touted
Brazilian researchers claimed last week the Sinovac was 78 per cent effective
But this data did not include ‘very mild’ cases which did not require treatment
With this included, it dropped to 50.4 per cent, barely enough for approval
China’s Covid vaccine is only 50.4 per cent effective, Brazilian researchers have found, just days after they announced results of 78 per cent from their late-stage trials.
The Brazilian Butantan biomedical centre announced last week the Sinovac Biotech jab had proved 78.4 per cent effective against ‘mild to severe’ cases which required treatment.
But it has now been revealed their results did not include ‘very mild’ infections from those who had received the vaccine but did not need medical assistance.
With this data included, the success rate has now dropped to 50.4 per cent, barely sufficient for the 50 per cent minimum for regulatory approval.
It is also well below the 70 per cent recommended by the Chinese government and the World Health Organisation.
The news is a major disappointment for Brazil, as the Chinese vaccine is one of two that the federal government had lined up to administer during their deadly Covid surge.
Sinovac’s chairman has insisted the vaccine is highly effective and prevents 100 per cent of severe Covid cases.
Many have criticised the Butantan biomedical centre for releasing partial data just days ago that generated unrealistic expectations.
The results came from a trial of 13,000 people in Brazil in the most advanced final phase of testing.
The trial saw 220 people infected of which 160 were in the placebo group and 60 received the vaccine.
They insisted last week the results were sufficient for ‘clinical efficacy’ and are insisting the vaccine is still 78 per cent effective in preventing mild cases that would need treatment.
It is still not clear how the efficacy rate was calculated by the Brazilian officials and a detailed breakdown of the study, showing age groups and side effects, has not been published.
The confusion may add to skepticism in Brazil about the Chinese vaccine, which President Jair Bolsonaro has criticized, questioning its ‘origins.’
‘We have a good vaccine. Not the best vaccine in the world. Not the ideal vaccine,’ said microbiologist Natalia Pasternak, criticizing Butantan’s triumphant tone.
Ricardo Palacios, medical director for clinical research at Butantan, said on Tuesday that the new lower efficacy finding included data on those ‘very mild’ cases.
‘We need better communicators,’ said Gonzalo Vecina Neto, a professor of public health at the University of Sao Paulo and former head of Brazilian health regulator Anvisa.
Sinovac chairman Yin Weidong said on Wednesday: ‘This data shows that the vaccines have good efficacy and safety in all the phase 3 clinical trials. We have accelerated the ramping up of production capacity.’
He added that the jab was 100 per cent effective at preventing severe cases, 78 per cent effective against cases requiring treatment and 50 per cent effective at ‘protecting medical workers’.
Weidong also cited figures from other trials which showed a much higher efficacy rate.
Piecemeal disclosures about Chinese vaccine trials globally have raised concerns that they are not subject to the same public scrutiny as US and European alternatives.
Palacios and officials in the Sao Paulo state government, which funds Butantan, emphasized the good news that none of the volunteers inoculated with CoronaVac had to be hospitalized with COVID-19 symptoms.
Public health experts said that alone will be a relief for Brazilian hospitals that are buckling under the strain of surging case loads. However, it will take longer to curb the pandemic with a vaccine that allows so many mild cases.