Across Chile — which has mounted one of the world’s most rapid vaccination campaigns using the vaccine made by Chinese drugmaker Sinovac Biotech Ltd. — health authorities are scrambling to deal with a surge in new infections and deaths.
More than 7.6 million people, half of Chile’s adult population, have received at least one vaccine dose, most made by the Chinese drugmaker, making the country a testing ground for a vaccine Beijing is supplying to countries across the developing world.
The problem, public-health officials say, was that people in general overestimated the effectiveness of the vaccine after only one of the two recommended doses and moved to ease up on pandemic-control restrictions too soon.
“With one dose, we know the protection is very weak,” said Claudia Cortes, an infectious-disease expert at the Santa Maria Clinic in Santiago, where about 10% of the Covid-19 patients at her hospital have received one shot. “It was not clearly explained that you need two doses — that you need to wait.”
THE LATEST results for China’s CoronaVac vaccine, developed by Sinovac Biotech, a Beijing-based pharmaceutical company, were disappointing for the aspiring scientific and technological powerhouse. Phase-three trials, which were conducted on health-care workers in Brazil, yielded an efficacy rate of just 50.7% (with a 95% confidence interval of 35.7% to 62.2%), just barely above the 50% threshold set by the World Health Organisation for covid-19 vaccines (see chart). The results of a real-world trial released a week earlier were even worse: the vaccine was estimated to be just 49.6% effective (11.3% to 71.4%) against symptomatic covid-19 cases; when asymptomatic infections were included, this figure dropped to a dismal 35.1%.
The Chinese authorities’ reaction did little to boost confidence. After news broke of the discouraging results, Gao Fu, head of the Chinese Centre for Disease Control and Prevention, admitted at a conference on April 10th that current vaccines “don’t have very high rates of protection”, and suggested that vaccines could be mixed to improve efficacy. Mr Gao later backtracked from the comments, claiming that it was “a complete misunderstanding”.