We disagree that vaccine quality control is a problem in China (Nature 507, S12–S13; 2014). In 2013, for example, the agency responsible for the country's vaccine quality control — the National Institutes for Food and Drug Control (NIFDC) in Beijing — was designated as a World Health Organization Collaboration Center for Standardization and Evaluation of Biologicals.

Since 2002, China has implemented batch release of vaccines as a key quality-control measure to ensure that they are safe to use. Each batch is screened by the NIFDC before its release. China produces about 4,000 batches of vaccines annually, corresponding to some 700 million doses.

In 2011, eleven batches of vaccine were rejected because they were of sub-standard quality; three were rejected in 2012 and four in 2013. Together, these represent a total of 1 million doses and correspond to just 0.05% of throughput over three years — a mark of China's stringent vaccine-production processes and of the success of batch-testing practices.