Coronavirus: Brazil finds China’s Sinovac vaccine to be less effective than previous data shows

Name: Brazil study shows China’s Sinovac vaccine less effective than earlier data on the Covid-19 shots
Uploaded: 2021-01-12T17:21:57.000Z
Duration: 2 min 29 s
Description: Brazil study shows China’s Sinovac vaccine less effective than earlier data on the Covid-19 shots

The new rate is a result of patients who displayed ‘very light’ symptoms being included, says Brazilian research institute that conducted the clinical trials

New CoronaVac ‘general efficacy’ figure from the Butantan biomedical centre comes after pressure for more transparency amid piecemeal disclosure and delays

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02:29

Brazil study shows China’s Sinovac vaccine less effective than earlier data on the Covid-19 shots

Eduardo Baptistain Lisbon

Published: 1:21am, 13 Jan 2021Updated: 9:08pm, 13 Jan 2021

Corrected [9:08pm, 13 Jan, 2021]

[9:08pm, 13 Jan, 2021]
An earlier version of this article stated that 3,410 Pfizer-BioNTech vaccine trial participants with Covid-19 symptoms were not tested for Covid-19. It has been corrected to clarify that they tested negative but were not included in the total efficacy rate.

A Chinese vaccine has been found to be significantly less effective than previous data had suggested, even as the Brazilian research institute that conducted the phase 3 clinical trials urges the public not to focus on the new efficacy rate.

The São Paulo-based Butantan Institute – which is running final-stage clinical trials for CoronaVac, manufactured by Beijing-based Sinovac – submitted new data to Brazil’s health regulator on Tuesday, listing an efficacy rate of 50.4 per cent. The numbers were confirmed at a press conference by officials from the research institute, which is funded by the São Paulo state government.

Ricardo Palácios, medical director of clinical research at Butantan, said the lower efficacy rate was caused by the inclusion of patients who were infected with the novel coronavirus but only displayed “very light” symptoms.

Phase 3 trial data for the US-based Pfizer-BioNTech Covid-19 vaccine, for example, gives a 95 per cent efficacy rate. The 44,000 volunteers, all of whom had tested negative for Covid-19, included 3,410 participants who displayed Covid-19 symptoms and were not included in the total efficacy rate, according to a US Food and Drug Administration report. In the unlikely event that all of those 3,410 had been false negatives, the total efficacy rate would drop to below 30 per cent.

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Last week, the São Paulo government said that CoronaVac was found to be 78 per cent effective in preventing mild cases of Covid-19 and 100 per cent effective against severe and moderate infections. The press conference on Tuesday confirmed these numbers and gave exact figures for both the vaccinated and placebo groups, at every level of severity.