Viral infectious diseases play critical roles in causing high mortality and morbidity for humanity. To evaluate the success of the vaccination program and to assess the efficacy of preventive measures, it is important to monitor the spread of some significant viral infections. Hepatitis diseases are one of the most critical infections worldwide due to their lethality level, transmission path, disease progression, patient age, and sex. In Saudi Arabia, the total number of hepatitis-infected cases decreased over the years, which shows the significance of the infection control guidelines followed in the country. The HBV infection rate is high among adults aged over 30–59 years compared to younger individuals, with 23,219 cases reported, despite the implementation of a mandatory immunization program in Saudi Arabia. This may be due to a decline in the seroprotection rate over time [7], necessitating an additional booster dose for each previously vaccinated person to raise the immune protection against this viral disease. Moreover, HAV infected males more than females, and the incidence was higher in the Riyadh region than in any other region, a finding which agrees with the reported study [8]. Most likely, this difference is attributed to spontaneous clearance in females and to sex hormones [9]. On the other hand, the risk of cross-border transmission of food-borne HAV infection increases with increased trade and travel between countries, so infection control requires international cooperation and safer practices. Additionally, the prevalence rate has decreased as a result of improved preventive measures and living conditions [8]. Recent vaccination studies against HAV in both Saudi Arabia and Turkey during childhood have shown significant prevention strategies and vaccine application policies in other countries [10]. Based on the data collected from the Saudi Arabia MOH, hepatitis vaccination and other infection prevention and control have led to a reduction in the prevalence rate among the population.

Moreover, vector-borne viral diseases, which include DF, DHF, AF, chikungunya fever, and WNV usually occur in tropical areas that have a massive number of insects leading to a high risk of infection. The prevalence rate of DF has been controlled in Saudi Arabia by using fogging and applying a biocontrol approach of the Wolbachia, a bacteria which is a natural and environmentally friendly method that does not involve the use of chemicals or genetic modification of the vector-borne replacement technology [11] that is taking place in Jeddah, which is an endemic city in Saudi Arabia [12], as an attempt to reduce and eradicate dengue prevalence. The Wolbachia-based biocontrol strategy was implemented in 2021, proposing an alternative strategy for reducing DF. This strategy has been lauded by the WHO and the CDC of the United States as one of the most effective and efficient methods for controlling DF [13, 14]. According to the WHO, the region of South American dengue outbreaks had almost 3 million suspected, confirmed, and reported cases in 2023, with Brazil, Bolivia, and Preu, which are tropical countries, having the highest number of dengue cases [15]. Based on the MOH reports, the total number of infected cases in Saudi Arabia is expected to reduce, based on the prevention, control, and vaccination strategies being followed.

Respiratory viral infectious diseases pose a constant threat to human life, initially presenting as a mild illness that may progress to respiratory failure. Respiratory viral infectious diseases are highly contagious and can be deadly due to their transmission and spreading through the air, and through direct and indirect contact with the infected person or contaminated surfaces. Based on the period of 2018–2021, the reported infected cases in Saudi Arabia have decreased due to the application of prevention and treatment. Globally, it was estimated that the seasonal influenza is responsible for 294,000 to 518,000 deaths annually [16]. Worldwide, preventive measures have been implemented to limit the spread of COVID-19, and investigations have shown the effectiveness of these measures in limiting the spread of several respiratory viruses [17]. Yearly in the United States, the reported ILI cases reached 50 million [18], whereas, in Saudi Arabia, the reported cases did not exceed 1000 in the period of 2018–2021 (Table 1; Fig. 1C). In general, the prevalence rate of respiratory viral diseases internationally is high through outbreaks or seasonal changes due to symptoms similarities and transmission. Applying restrictions such as social distancing significantly affects and reduces the spreading of many respiratory viral infectious diseases and, in some countries, such as South Korea, the reduction reaches 100% [19]. In Saudi Arabia, a recent study has shown that the pandemic COVID-19 has affected and impacted the number of influenza cases [20], which meets and agrees with this study’s findings. In the case of respiratory viruses that have an impact on public health, proper ventilation, cleanliness, and immunization against flu viruses are essential, especially for elderly and chronic illness patients.

Exanthematous infections such as chickenpox and measles are common in Saudi Arabia; however, the total number of cases has been reduced and controlled by the mandatory vaccines included in the childhood vaccination schedule. Noteworthy, the chickenpox vaccination program in the United States has impacted the prevalence rate and shown a significant reduction in the reported cases [21]. China has reported a decrease in the cases of rubella, measles, and chickenpox during the COVID-19 pandemic, and this significant reduction in infection rate was due to preventive measures implemented during the COVID-19 pandemic [22]. This report agrees with our findings that, from 2018 to 2021, the total number of cases has been reduced and controlled by vaccination and prevention approaches, even for other exanthematous infections that require early detection and isolation to reduce the infection rate.

Neurological viral infectious diseases are rarely found in Saudi Arabia. According to this finding, rabies cases were rarely reported from 2018 to 2021. However, a study examined 199 animals suspected of rabies in Saudi Arabia during 2010 and 2017 where 158 of them were infected with rabies, and most of them were dogs and cats. The most common cases are in the Qassim region, followed by the Eastern region. The study recommended implementing measures to eradicate rabies, which may pose a risk to farmers and veterinarians, as dogs, camels, and livestock animals are considered reservoir animals [23]. Interestingly in Western Europe, rabies disease has been eradicated for about 15–20 years [24], opposite to the situation in Nigeria, where the risk factors for rabies transmission are high due to the high rates of dog bites [25]. From 2018 to 2021, neurological viral infectious diseases had less than five reported cases according to the MOH database, which was a lower percentage than for other reported viral infectious diseases (Fig. 1E). Due to the preventive strategies that are followed in Saudi Arabia, which include high infant and children immunization, and vaccination for adults at high risk of infection, travelers from endemic countries are tested and follow the implemented programs [26].

Furthermore, based on the results of this current study, sex variations were observed in several viral diseases, such as HBV, HCV, DF, and chickenpox, which may occur due to several reasons, including that females are generally greater in adaptive and innate immune responses than men, the innate immune cell activity in females is greater than in males, and females have greater thymus cell helper (T cell) counts and ratios compared to males [27]. Another reason is that some women may have an asymptomatic infection [28].

Despite this study demonstrating epidemiology data of viral infections reported in Saudi Arabia, numerous cases were unreported, which may be due to the challenges involved in the epidemiological surveillance process. The three key challenges facing epidemiological surveillance globally: interface challenges (i.e., the method used to show data to a consumer for consumption), data format challenges (i.e., the read and write processes for the data); however, these averages may include individual items influenced by various factors, such as age or geographical region. The statistical data reflect information from recent years between 2018 and 2021 where the number of cases were provided by the FETP every month and not beyond this duration. These results might also be impacted by the COVID-19 pandemic due to the strict precautionary measures imposed by the MoH, including curfews, which could lead to underreporting of viral infections. Additionally, measures like wearing masks and social distancing contributed to reducing the spread of respiratory viruses. Even so, working on the previous challenges will result in a more comprehensive reporting system, which will be the basis for burden planning and health priority. All the abovementioned factors could serve as study limitations that may open the door for improvements in future epidemiology studies.