The quality of national HIV surveillance systems, using the same approach to score countries as that applied in 2007, continues to reflect considerable variation, within and across regions. In sub-Saharan Africa, where over 68% of the global number of HIV infections occurs, the surveillance systems continue to be of generally good quality, particularly in Southern Africa, with the world's highest HIV prevalence. Moreover, the number of ANC sites has continued to grow, an increase largely attributable to new sites included in surveillance systems in South Africa. Eight countries have conducted two or even three national surveys. More HIV surveillance data in many countries have led to improved assumptions in the estimation methodology, and the HIV estimates in these countries have become more accurate over time. Furthermore, these countries estimate HIV incidence levels using modelling or alternative approaches, and results can be compared to assess the validity of findings.14
In several countries, HIV surveillance systems have deteriorated in the last 2
years and are not performing as well as they should. This is especially the case in Central Africa and in some countries in East and West Africa that have been involved in recent political unrest.
High-quality surveillance systems are found in South and Southeast Asia. Like sub-Saharan Africa, the epidemics in some countries in this region are older than the rest of the world, and surveillance systems in countries with mature epidemics are generally functioning well. Only about a third of the surveillance systems in Latin America and the Caribbean have sufficient information to qualify as fully functioning surveillance systems. In the other regions (North Africa and the Middle East, and Eastern Europe and Central Asia), surveillance systems are either partially functioning or functioning poorly.
The results of this assessment reveal weaknesses of HIV surveillance systems in too many (56 of 138) of the evaluated countries, especially in countries with a low level of HIV infection or where the epidemic is concentrated in certain population groups. The number of such countries with studies considering MSM has increased overall, and there are now more data available on this population in many regions, including Africa. Because of a lack of consistency in surveillance efforts, it is very difficult to assess trends, but substantial progress has been made in studying the epidemic within this group in the last few years. Regarding FSWs, the number of studies has decreased in recent years, and in most countries no trend data are available. In countries in Central and Eastern Europe, most of the epidemiological data available are on injecting-drug users, but even in these countries trends in the epidemic are difficult to monitor due to the lack of systematic methods to undertake surveillance studies.
When compared with 2007 results, 35 countries have fully functioning systems in 2007 versus 40 in 2009, and 45 have partially functioning systems in 2007 versus 47 in 2009. Poorly functioning systems increased from 53 in 2007 to 56 in 2009. Even though there is a small increase on number of countries with not functioning systems, those countries represent a small proportion of the global burden of disease. Therefore the great proportion of the new global HIV estimates are based in countries with good surveillance systems.
The countries in North Africa and Middle East, with a few exceptions, continue to have limited HIV surveillance activities. While there are now more data available than before, trends in the epidemic can still not be assessed, and the countries in this region therefore received low scores.
One of the reasons why countries remain in either score with poor or partially systems is mostly because of the lack of consistency of methods and tools. Even though some countries have increased the number of surveys and have more data in different population groups, the instruments and tools used for survey are different. Most of the countries are using Respondent Driving Sampling (RDS) as a strategy for sampling on high-risk groups. However, in the past, other approaches such as venue sampling or time location sampling have been used, so it is not possible to construct trends.
This paper considered data available for the last 9 years to assess the quality of surveillance systems that are being used for monitoring the HIV epidemic. In countries with the greatest disease burden, surveillance has continued to improve over time, and the addition of large population-based HIV prevalence surveys in these countries has greatly enhanced the reliability of the data. In many other countries, specifically those with low-level and concentrated epidemics, the quality of data has remained very similar, although many countries still lack the consistency required to follow trends over time in high-risk populations. There are gaps in some country data on high-risk populations, and behavioural data are generally scarce.
The parameters used to score surveillance systems are not perfect, as scoring is based on public reports. Because providing trends is one of main properties of sentinel surveillance, the frequency of surveys has more weight than the other parameters. The longer the time assessed, the more weight this parameter carries. Recent data on the timeliness of information is another important parameter as it assesses whether surveillance data are recent or not, and it has implications for the estimates produced at the country level.15
In spite of the limitation on the scoring system, similar parameters and weights were kept to compare them with the 2007 assessment of quality.
There are several limitations in this analysis. First, we may have not access to all the surveillance reports and studies conducted in countries that remain in the grey literature. Second, the assessment criteria may be unfair to small countries with low epidemic levels. Those countries may have opted for surveillance systems based mostly on case reporting, rather than surveys. In these local communities, integrated behaviour surveys among populations with high-risk groups may be very difficult to undertake. Lastly the score system is not perfect, as intends in assessing HIV trends and coverage of HIV surveillance among different populations. It does not address other issues as qualitative surveys or the use of data.
Every effort has been made to contact regional experts and national epidemiologists via WHO regional offices and to ensure that most recent surveillance data have been identified for this study. Appropriate data for the assessment of surveillance quality in low-level or concentrated epidemics were limited to high-risk populations, while the analysis in countries with generalised epidemics was based on antenatal clinic surveillance and population-based surveys that include HIV testing. Other sources of data that are used in countries for monitoring the epidemic, such as blood screening mechanisms, were not captured here. Publications in languages other than English, French, Spanish or Russian were not considered in this study.
Several recommendations can be made based on our analysis. First, there is a need to review and assess HIV surveillance system periodically, to see if HIV surveillance systems are responding to the needs of the countries.15
These reviews or evaluations can be made regularly by national experts, and occasionally by external experts. Second, the consistency of methods, tools used, populations and geographical locations are the key parameters for surveillance to detect trends and overall burden of disease. Third, resources should be made available to improve the quality data collected.
- The quality of HIV surveillance systems remains at the same level as that for 2007 in high-burden countries.
- More national population surveys have been conducted worldwide, and these provide better coverage in generalised epidemics.
- There is a need to review and evaluate HIV surveillance systems on a regular basis.
- A significant number of countries still need to improve their HIV surveillance systems.