STDs remain the most common contagious diseases worldwide. According to the data of WHO, the estimated new infections of syphilis and gonorrhea were about 6 million and 78 million globally in 2016 . By 2020, about 77.5 million people have been infected with HIV worldwide, and approximately 34.7 million people have died from AIDS-related diseases since the first case of HIV infection was reported .
In China, HIV infection, syphilis and gonorrhea are national statutory infectious diseases, and the incidence of these three STDs showed a trend of increase in the recent 20 years [13, 14]. According to the latest reports from the Administration for Disease Control and Prevention of China , there were 62,167, 464,435 and 105,160 people infected with HIV, syphilis and gonorrhea in 2020, respectively, which were dramatically decreased by 12.7% (71,204), 13.3% (535,819) and 10.8% (117,938) compared with that in 2019. As our results shown (Fig. 1), the incidence of HIV infection and syphilis presented a trend of increase from 2008 to 2019, while the incidence of gonorrhea presented a form of smooth fluctuation. However, this trend of increase was broken in 2020. The incidence of HIV infection, syphilis and gonorrhea dramatically declined by 13.1%, 13.8% and 11.4% in 2020 compared with that in 2019, respectively, as shown in our results (Fig. 1).
China experienced the COVID-19 pandemic at the beginning of 2020. Though the epidemic first broke out in Wuhan, the run on medical resources caused panic across the country . At the same time, the government quickly introduced policies to contain the spread of the epidemic, such as city lockdown, home-staying, keeping social distance, wearing masks, hands hygiene, emergency medical assistance for COVID-19, which effectively prevent and control the spread of COVID-19 to some extent [12, 27, 28]. However, all those measures have had a profound impact on sexual health and behavior of individual . As reported by Bonett, Stephen et al.  the disruptions in STDs testing infrastructure during the COVID-19 pandemic threaten to impact STDs service. The STDs test counts decreased and test positivity increased during the pandemic period. According to the report from Greece, Cuba and other countries, the epidemiology of STDs has been widely affected by the COVID-19 pandemic, and presented a trend of dramatic decrease [5, 8,9,10]. The same situation could happen in China, in our unpublished data at the STD clinic in Shanghai Skin Disease Hospital, we found that patients with STDs interrupted follow-up at the beginning of the COVID-19 outbreak, and the first visit patients sharply declined. Our observed reduction of hospital visits in patients with STDs during COVID-19 pandemic, similar to other non-COVID-19 related disease reported elsewhere . Two out of the three STD clinics of our hospital which were located in the center of Shanghai were closed meanwhile. Based on a survey in our hospital (data unpublished), people reduced their high-risk sexual behavior for fear of being infected with COVID-19. In this study, we analyzed the extent of the impact of COVID-19 pandemic on the epidemiological trend of STDs in China. We found that the APE of HIV infection, syphilis and gonorrhea in 2020 was about 7 times, 4 times and 2 times of that in 2019, which revealed a significant change of the epidemiology of STDs in 2020, especially HIV infection and syphilis. Though it is not clear whether the sharp decline in the incidence of STDs in 2020 was due to the fact that the STDs was hidden by the COVID-19 pandemic, or that STDs had been controlled because of the policy of “city lockdown, home-staying, keeping social distance”, or that people reduced their high-risk sexual behavior during COVID-19 pandemic, due to the fear of and anxiety about the highly contagious characteristics of COVID-19, we suspect that both might contribute to the decline of the incidence of STDs in China.
Although vaccination for the COVID-19 is one of the most effective methods for the general improvement of social safety and individual health  and the non-pharmaceutical prevention strategies, such as keeping social distance, using face mask could play a notable role in containing the transmission of COVID-19 for vast majority of the population , the strict prevention strategies such as city lockdown, home-staying are still performed to reduce COVID-related morbidity and mortality in China. However, just like what previous researchers pointed out “the intensity of interventions required needs to be balanced against the wider health risks that diverting all attention to a single disease could entail” . Similar to ours, researches of other countries have shown that the COVID-19 epidemic has great impact on STDs [7, 11]. Therefore, the prevention and control of STDs still needs more attention from the society during the COVID-19 epidemic.
In 2020, under the influence of COVID-19, the prevention and treatment of STDs may somewhat be hindered. The research reported by Pascoal, et al. highlighted the role of mental health in the impact of COVID-19 on sexual health . Due to the increasing difficulty in the supervision of STDs during COVID-19, the real situation of the epidemiology of STDs may be underestimated, and STDs incidence might rebound after a long-term development, resulting in a more serious disease burden of society. Therefore, except for emphasizing those well-known policies to prevent STDs , such as education on sexual healthy, condom use and partner notification, it is very important that in the event of major pandemics, medical resources should be reasonably allocated, especially for people with HIV, for higher acquisition rates and a poorer outcome of COVID-19 infection in people living with HIV are expected . As such, when managers strengthening pandemic control, the medical aid resources for STDs should be protected from damage, to prevent increasing heavier burden of social diseases in the long run. Different guidelines should be designed and accurate evaluation is required for STDs patients with COVID-19. A better management with special consideration must be given to patients with STDs, such as against discrimination on STDs, encourage self-testing and online medical care, offer necessary remote consultation and medical support, express delivery drugs and special medical pass when lockdown during the COVID-19 pandemic. Evidence has shown that mobile health (mHealth) in mobile apps has been used to enable health care providers to reach out to vulnerable individuals, to provide counselling, health-related education, and treatment . As shown in a study by Pant Pai et al. , an unsupervised HIV self-testing strategy using an internet-based mHealth provided counselling and treatment among patients testing positive in South Africa. It’s worth noting that the mobile app organization should boost health care professionals’ core competence with regard to telemedicine, and effectively supervise the quality of mHealth. Moreover, people’s mental health should be guided in a timely manner. The official notice should play a positive role in guiding the real-time reporting of the pandemic, guiding the public to prevent diseases with scientific means, to reduce the fear and anxiety of people caused by the pandemic.
This study also predicted the burden of STDs in 2021, which showed a trend of increasing incidence, warning that we should always keep an eye on the transmission of STDs seriously in China. And with the pandemic well controlled in China for that time, a much little difference between predictive and real infection rate would be strong evidence to prove our findings.
There are some limitations in our study. As we mentioned above, GM (1,1) model is a time-series model , and “Simplicity and efficiency” are its advantages. However, using a time-series model to predict the trend of STDs has its inevitable limitations, because the time-series predictive model mainly emphasizes the influence of time factor, which cannot comprehensively show the influence of various other factors. While for STDs, the sexual behavior of the population dictates the incidence and trend of the pandemic. As mentioned, the pandemic of COVID-19 could have impacted on the epidemiology of STDs in several ways. Positively, it could reduce the chance of high-risk sexual behaviors. Because of social-distancing and lockdown, casual and commercial sexual intercourse would decline and the incidence of STDs would be reduced. Negatively, COVID-19 might disrupt healthcare services, such as HIV testing, following and distribution of antiretroviral therapy (ART) drugs, and all these increases the risk of STDs transmission. Furthermore, the number of diagnoses during COVID-19 also drops probably due to less testing has been conducted. Therefore, the GM (1,1) model in this study might not reflect the actual transmission of the three diseases.
Based on the analysis of the impact of COVID-19 pandemic on STDs, we recommend that vaccination for the COVID-19 should be given to people, including those with STDs. And the non-pharmaceutical prevention strategies must be undertaken by the STDs patients to protect themselves during the pandemic. Medical aid resources for STDs should be reasonably allocated and protected from damage. Special guidelines should be designed for STDs patients with COVID-19, including self-testing, online medical care, remote consultation and medical support, timely diagnosis and treatment guarantee, special medical pass when lockdown during the COVID-19 pandemic.