With a population of over 1.3 billion people and an annual increase of 16 million, China requires 500 million vaccine doses each year. Recent additions to the national immunization schedule combined with China’s enormous population have seen the vaccine market increase at an astronomical rate.

Little post-marketing surveillance data for Adverse Events Following Immunization

Despite massive growth in China, there is limited post-marketing surveillance (PMS) data for Adverse Events Following Immunization (AEFI). However, what little data has been captured shows comparable results to PMS systems in other countries.

PMS data around Japanese Encephalitis analyzed by Chengdu scholars

Japanese Encephalitis (JE) is the most severe form of viral encephalitis in Asia and has no specific treatment. Vaccination is the most effective way to prevent JE.

In a recent clinical study, a team of scholars analyzed AEFI post-marketing surveillance data related to the SA-14-14-2 JE vaccine produced by the Chengdu Institute of Biological Products.

Analyzing three years’ worth of data (2009 to 2012), the AEFI report showed that out of 6024 AEFI cases, only 70 AEFI cases were severe. Furthermore, they only found 9 cases of meningoencephalitis and 4 cases of death. Based on this PMS data, the team concluded that it is relatively safe to use the live attenuated vaccine for JE.

Japanese Encephalitis discoveries by Guangdong scholars

A team of scholars from Guangdong Province, China, analyzed the PMS data for AEFIs of a live attenuated Japanese encephalitis vaccine between 2005 and 2012. For analysis, they used 23 million doses of the live attenuated Japanese encephalitis vaccine during this 7-year period.

Over the 7-year period, their PMS data showed only 1426 AEFI cases amongst the 23 million doses. Within the 1426 AEFI cases, there were 570 cases of allergic reactions, 36 cases of serious adverse events, and 31 cases of neurologic events.

With the exception of a few serious cases, the Guangdong team’s data further demonstrates that the live attenuated Japanese encephalitis vaccine is relatively safe. Any other adverse events are mild.

Outbreak of H1N1 and PMS data results from AEFIs

In 2008, the Chinese National AEFI Information System (CNAEFIS) was implemented and has been providing national-level data on vaccine safety.

In 2009, there was an outbreak of Influenza A (H1N1) in China. Between September 21, 2009 and March 21, 2010, a total of 89.6 million doses of the H1N1 vaccine were administered.

According to CNAEFIS, of all the doses administered, there were only 8067 reports of AEFIs resulting in a 90 to 1 million ratio of doses to adverse events. Most AEFIs were not serious and the PMS data suggests the H1N1 vaccine has an acceptable safety profile.

The state of PMS data gathering for AEFIs

Despite the Chinese vaccine market’s rapid growth, PMS data for AEFIs continues to be in short supply. The sparse amount of AEFI data that has been gathered has shown the live attenuated Japanese Encephalitis and Influenza A (H1N1) vaccine safety profiles to be reasonably safe. As PMS data gathering institutions continue to expand, we look forward to a vast potential amount of PMS data gathered around AEFIs in China.