Within three decades, since first case of HIV infection was reported in Ethiopia, almost 1.93 million people have been infected with HIV and about 1.3 million (67.4% of infected peoples) have died of AIDS-related causes [8,9,10]. The national HIV prevention and treatment programmes has made considerable progress in addressing this unprecedented epidemic and averted many more new infection and AIDS related death. Since then, the burden of HIV/AIDS infection had declined at the national and regional levels through early diagnosis, treatment and care [4, 11,12,13]. However, still HIV is a public health problem in the country. In order to overcome this problem Ethiopia has adopted the 90–90-90 HIV prevention target by 2020 in 2014/5 in order to end AIDS epidemic by 2030 [4, 5].
In 1990s a substantial increment in the number of people living with HIV and new infections among all ages was observed throughout the country. These national HIV/AIDS metrics are in line with the global HIV epidemic pattern [9, 14]. Between the periods of 1990–1995 the number of new infection has sharply risen from 100,000–160,000 per year. It resulted in continuing large number of people living with HIV in 1997–2002, where nearly 1.1 million people were living with HIV in Ethiopia. Higher number of new HIV infection until the 1995  and improved survival of people living with HIV/AIDS owing to the initiation of ART program [4, 15, 16] resulted in high prevalence of HIV until 2002. However, after the prevention programmes have expanded throughout the country, new infection and prevalence of HIV has declined remarkably.
The pace of decline in new HIV infection and prevalence is not even across different age groups and between regions. Among children, new infection has declined from 27,000 in 1998 to 3300 in 2014 and prevalent cases from 130,000 in 2007 to 62,000 in 2016. This is particularly resulted from wider use of improved ARV medicine regimens and improved PMTCT service [4, 16]. Moreover, The Global Plan towards the elimination of new HIV infections among children by 2015 and keeping their mothers alive which is implemented in Ethiopia as well, added strong achievement in the prevention program . The decline of new HIV infection and prevalent cases however do not sustained after 2008 among adults, virtually the entire decline in HIV incidence has majorly resulted from reduction of infection among children [16, 17].
The trend of HIV prevalence depicts a heterogeneous epidemic in the country, with the highest prevalence regions being Addis Ababa (4.8%), Gambela (4.5%), Hareri (3%) and Dire dawa (2.8%), which is much higher than the national average prevalence and the level of generalized epidemic declaration. Similarly, the incidence of HIV in these regions is by far higher than the national average. The reason why HIV is more prevalent in these areas may be due to the fact that these are the major cities and trade routes of the country in which migrants from different corner of the country migrate for job and became highly vulnerable for HIV [4, 5, 13]. In addition to this the case of Gambela was explained with lower male circumcision rate in the region .
Besides remarkable reduction in HIV epidemics, the current epidemics observed since 2009 among adult is another challenge which needs a due attention. Since this period incidence of new HIV among all age in all regions rose sustainably as a result of increased new infection among adults which account for the vast majority of people newly infected annually. This trend is in line to the global trend of HIV which indicates the world is performing poorly in preventing sexually active people from acquiring HIV [5, 14]. Therefore, as new infection was prevented among children through prevention of Mother to child transmission, the global strategy should also address the sexual transmission of HIV among adults.
Nationally, coverage of ART treatment has expanded from 31% in 2010 to 59% in 2016 nearly doubled within 6 years. The estimated ART coverage in Ethiopia is comparable to the Eastern and southern Africa regional average of 60% and higher than the regional averages of Middle east and north Africa (24%), western and central Africa (35%), Asia and the pacific (47%), Latin America (56%) and Caribbean region (52%). While it is lower than the regional average of western and central Europe and North America of 78% coverage. This could be due to difference in access, retention and difference in implementation of the program [14, 19]. In Ethiopia, access is highly expanded in current few years, retention is higher (90%) and furthermore integration of the ART program with Health Extension package (HEWs) and involvement of Health Development Army (HDA) to HIV care services highly contributed. Yet, this increment in the coverage of HAART did not limit the new infection observed in recent years due to higher rate of HIV sexual transmission among adults .
Furthermore, implementation of test and treat program, strengthening of PMTCT program and achievement of higher retention in ART program resulted in suppression of viral load and averted many more new infections and AIDS related death [4, 14, 21]. The reduction of new infection among children that contributed for the reduction of HIV prevalence among the general population was basically a result of this PMTCT program. The ART program also has higher contribution in the prevention of transmission among adults . The trend of coverage had dramatically increased in all regions since 2010, except for the last 1 year in Hareri and 2 years in Addis Ababa regions that could be related to the increase in prevalence of HIV in recent years.
The fact that HIV is one of the major causes of morbidity and mortality in Ethiopia was reported from previous studies [4, 5, 13, 22] as it was in many other developing countries . Since 1990, 1.3 million people (50,000 people each year) were died from AIDS related cause. Such higher level of mortality was also seen in many of sub-Saharan countries where access to life saving HAART is low and the risk of HIV progression and related mortality is high [20, 21].
The trend of AIDS related death has a sharp rise from 1990 to 2002 and 2003 when it reached a peak among children and general population respectively and stared to decline sharply to 2016s level. Since then, the annual number of deaths from AIDS declined as well and a decade later it was almost a quarter when 18,000 people died in 2016. Much of the decline is due to steep reductions in new HIV infections among children with increased access to pediatric antiretroviral therapy and strengthening of PMTCT service [16, 20, 21]. The reduction of new HIV among adults appreciated since 1995 also contributed a lot for this achievement. Such a trend in reduction of AIDS related mortality was also achieved in the Caribbean, western and central Europe and North America, Asia and the Pacific and western and central Africa regions [20, 21].
Access to ART has direct impact on an individual’s risk of death, and on the country where one lives has a significant impact on death rates and life expectancy. Generally, early access to life-saving ART highly reduces AIDS-related death. Particularly in low-income countries and high HIV burden countries, annual burden of AIDS related death markedly increased due to low access of ART treatment. Besides early access, economic status of the clients also determines the mortality level of individuals related to HIV. In some lower income countries, people living with HIV have 10 to 20 times higher death rates than those living in some higher income countries .
In 2016, 67% of people living with HIV knew their status, 86% of people living with HIV who know their status were on treatment and 88% of people on treatment have viral suppression. This is by far greater than the regional average of 42, 83 and 73% for people who know their status, who are on treatment and who have viral suppression respectively in Western and Central Africa WHO region . Based on the trend prediction, by 2020, 79% of people living with HIV will know their status and 96–99% of people knowing to have HIV infection will initiate a treatment by the same year.
Ethiopia has made Remarkable progress towards achieving the 90–90–90 targets evidenced that attainment of the 90–90-90 target by 2020 is both feasible and reachable if gaps across the HIV testing and treatment cascade are promptly addressed. However, the first 90% target (90% of people living with HIV knowing their status) is not achievable in Ethiopia by 2020. While the second 90% target, (to treat 90% of people who know their status) will be achieved 3 years before the specified date. The third target (90% of viral suppression among those who are on treatment) was not predicted for its 2020 value because it is estimated only once in 2016 nationwide. However even by this point, around 86% of people on ART have viral suppression near to achieve the 90% target by 2016 4 years before the actual time frame.
The findings of this study might suffer from the fact that it is retrospective study and based on records; the reliability of the recorded data couldn’t be ascertained and potential bias associated with estimation is there. Moreover, the forecasted values from the trend may change through time due to change in intervention programs. The determinants of each outcome and the trend was not addressed which may have influence as well.