Multiple rounds of national estimation exercises have improved the accuracy of China’s HIV/AIDS estimates. Early estimates were based on limited data from high-prevalence areas and high-risk populations, and were hence higher than subsequent estimates based on more complete data from an expanded HIV surveillance system. Between 2003 and 2005, for example, national estimates of the number of PLWHA fell from 840 000 in 2003 to 650 000 in 2005. Two factors were primarily responsible for this drop.10
First, estimates in 2003 were most likely overestimated the epidemic but estimates in 2005 reflected the epidemic better since a wider range of data had became available, including data from a 2004 mass HIV screening of former plasma donors in central China and data from a greatly expanded HIV sentinel surveillance system. Secondly, more precise geographical units were used in preparing the estimates. In 2003, estimates were done at the provincial level, and the estimates were done at the prefecture level in 2005.
Between 2005 and 2009, HIV data availability continued to improve. First, the number of national and provincial HIV sentinel surveillance sites contributing data to China’s national HIV estimates increased from 929 sites in 2007 to 1029 sites in 2009. The largest increases were in the number of sites contributing data for female SWs (2007: 229 sites; 2009: 367 sites) and MSM (2007: 11 sites; 2009: 25 sites). This increase in number of sites reflects the growing importance of sexual transmission, which in 2005 overtook injecting drug use as the leading mode of HIV transmission. Secondly, more data are now available from expanded surveillance and special surveys. For example, three rounds of national surveys of MSM in 61 cities have provided more accurate assessments of HIV prevalence and risk behaviours within MSM communities around the country.
The quality of HIV data has also continued to improve. From 2007 to 2009, there was marked improvement in the proportion of HIV prevalence data classified as ‘excellent’ or ‘good’ across all populations. The quality of data used for population size estimates has also improved over time.
The increase of number of PLWHA may be influenced by two factors. First, with rapid scale-up of the national free antiretroviral treatment programme, PLWHA live longer.20
Secondly, even if a reduction of new HIV infections were observed, there are still a considerable number of people infected with HIV each year.
The rapid increase in HIV prevalence among MSM in recent years is a major cause for concern. Among both urban and rural MSM, estimated HIV prevalence has increased during each round of estimation since 2005. In 2009, MSM accounted for nearly one-third of new HIV infections in China.
For future HIV/AIDS estimation exercises, improvements still need to be made. There are still many data gaps to be filled. For example, further attention must be paid to HIV among the male clients of SWs and rural MSM. HIV surveillance sites need to be further expanded to cover smaller and medium-sized cities. Methodological limitations must also be addressed. The Workbook Method provides a good starting point for generating national HIV/AIDS estimates, but it may not accurately reflect the large regional differences in China’s HIV/AIDS epidemic. The Workbook Method also currently does not have the ability to generate estimates for a number of populations, including MSM >50-year-old, migrant wives, those infected via blood and or/blood products, mother-to-child transmission, sailors and foreigners.