National Overview of STDs, 2021
As noted in the 2021 National Academies of Sciences Engineering and Medicine report, Sexually Transmitted Infections: Adopting a Sexual Health Paradigm, surveillance is key to understanding the magnitude of sexually transmitted infections in the United States and in subpopulations that are most affected.1 The 2021 STD Surveillance Report provides trends in STDs to describe current epidemiology of nationally notifiable STDs and inform prevention and control strategies. This overview summarizes national surveillance data for 2021 on the three notifiable diseases for which there are federally funded control programs: chlamydia, gonorrhea, and syphilis, including congenital syphilis.
Because STDs often do not show symptoms, and screening is necessary for timely diagnosis and treatment, changes in access to sexual health care can affect the number of infections diagnosed and reported. Disruptions in STD-related prevention and care activities related to the US response to the COVID-19 pandemic had a pronounced impact on trends in STD surveillance data collected during 2020. It is likely that some of the disruptions persisted in 2021; therefore, trends presented in Sexually Transmitted Disease Surveillance, 2021 should be interpreted cautiously. For more information, please see Impact of COVID-19 on STDs.
In 2021, a total of 1,644,416 cases of Chlamydia trachomatis infection were reported to the CDC, making it the most common notifiable sexually transmitted infection in the United States for that year. This case count corresponds to a rate of 495.5 cases per 100,000 population, an increase of 3.9% compared with the rate in 2020. During 2020 to 2021, rates of reported chlamydia increased among both males and females, in all regions of the United States, among most age groups, and among all race/Hispanic ethnicity groups. Rates of reported chlamydia are highest among adolescents and young adults. In 2021, almost two-thirds (58%) of all reported chlamydia cases were among persons aged 15–24 years.
The increases in rates of reported chlamydia during 2020 to 2021 follow a substantial decrease in rates during 2019 to 2020. The decrease in rates of reported chlamydia in 2020 were unlikely due to a reduction in new infections. As chlamydial infections are usually asymptomatic, case rates are heavily influenced by screening coverage. During the COVID-19 pandemic, many health care clinics limited in-person visits to patients with symptoms or closed entirely, and it is likely that preventive health care visits where STD screening usually happens, such as annual reproductive health visits for young women, decreased. During the initial shelter-in-place orders in March and April of 2020, the number of chlamydia cases decreased substantially when compared to the number of cases reported at the corresponding time in 2019 and the deficit persisted throughout the year. Although the rate of reported chlamydia increased during 2020 to 2021, the rate is still lower than the rate in 2019 suggesting that COVD-19 related challenges related to chlamydia screening may have persisted during 2021.
In 2021, a total of 710,151 cases of gonorrhea were reported to the CDC, making it the second most common notifiable sexually transmitted infection in the United States for that year. Rates of reported gonorrhea have increased 118% since their historic low in 2009. During 2020 to 2021, the overall rate of reported gonorrhea increased 4.6%. During 2020 to 2021, rates increased among both males and females, in three regions of the United States (West, Northeast, and South), among most age groups, and among most racial/Hispanic ethnicity groups.
During the initial shelter-in-place orders in March and April of 2020, the weekly number of cases of reported gonorrhea was lower compared to counts during the comparable time in 2019; however, later in 2020, the number of reported gonorrhea cases increased. Reasons for the increase are unclear but may have resulted from increased service utilization as health care clinics re-opened or increased transmission later in the year. During 2019 to 2020, the rate of reported gonorrhea increased in 35 states and two US territories. This trend continued during 2020 to 2021, with increases in rates of reported gonorrhea in 27 states, the District of Columbia, and three US territories.
During 2020 to 2021, rates of reported gonorrhea increased among both men (6.3%) and women (2.4%). Since 2013, rates of reported gonorrhea have been higher among men compared to women, likely reflecting cases identified in both gay, bisexual, and other men who have sex with men (MSM) and men who have sex with women only. Although there are limited data available on sexual behaviors of persons reported with gonorrhea at the national level, enhanced data from jurisdictions participating in a sentinel surveillance system, the STD Surveillance Network (SSuN), suggest that about a third of gonorrhea cases occurred among MSM in 2021.
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Gonorrhea can quickly develop resistance to antibiotics used to treat infection. Based on gonococcal isolates collected through sentinel surveillance in the Gonococcal Isolate Surveillance Project (GISP), about half of all infections were estimated to be resistant or have elevated minimum inhibitory concentrations (MICs) to at least one antibiotic in 2021; however, almost all circulating strains in the United States remain susceptible to ceftriaxone, the primary recommended treatment for uncomplicated gonorrhea. In 2021, only 0.1% of isolates displayed elevated ceftriaxone MICs. Continued monitoring of susceptibility patterns to antibiotics is critical to inform gonorrhea treatment guidelines.
In December of 2020, CDC released updated gonorrhea treatment guidelines, recommending a single 500 mg intramuscular dose of ceftriaxone for uncomplicated gonorrhea.2 Despite continued disruptions in access to health care related to COVID-19 and the change in treatment recommendations, most reported gonorrhea cases in jurisdictions participating in the sentinel surveillance system, SSuN, in 2021 received the recommended treatment. Continued surveillance of treatment practices is a critical public health priority to help ensure that patients receive the highest quality of care, and to address the emerging threat of antimicrobial-resistant gonorrhea.
In 2021, 176,713 cases of syphilis (all stages and congenital syphilis) were reported, including 53,767 cases of primary and secondary (P&S) syphilis, the most infectious stages of the disease. Since reaching a historic low in 2000 and 2001, the rate of P&S syphilis has increased almost every year, increasing 28.6% during 2020 to 2021. Rates increased among both males and females, in all regions of the United States, and in all age groups. Rates of P&S syphilis increased in all racial/Hispanic ethnicity groups, with greatest increases among non-Hispanic American Indian or Alaska Native persons who also had the highest P&S syphilis rate in 2021.
MSM are disproportionately impacted by syphilis, accounting for almost half (46.5%) of all male P&S syphilis cases in 2021 and in areas with complete information on sex of sex partners for male cases, rates of P&S syphilis among MSM increased in 27 states and the District of Columbia during 2020–2021. Although rates of P&S syphilis are lower among women, rates have increased substantially in recent years, increasing 55.3% during 2020 to 2021 and 217.4% during 2017–2021, highlighting the sustained increase in the heterosexual syphilis epidemic in the United States.
The 2013 rate of congenital syphilis (9.2 cases per 100,000 live births) marked the first increase in congenital syphilis since 2008. Since 2013, the rate of congenital syphilis has increased each year. In 2021, 2,855 cases of congenital syphilis were reported, including 220 congenital syphilis-related stillbirths and infant deaths. Although the majority of congenital syphilis cases were reported from a few states, in 2021, almost all jurisdictions (46 states and the District of Columbia) reported at least one case of congenital syphilis; 37 states and the District of Columbia had increases in congenital syphilis during 2020 to 2021.
The national congenital syphilis rate of 77.9 cases per 100,000 live births in 2021 represents a 30.5% increase relative to 2020 and 219.3% increase relative to 2017. These increases mirror increases in syphilis among reproductive aged women. During 2020 to 2021 the rate of P&S syphilis increased 52.3% among women aged 15–44 years and rates increased in 45 states. Further, in 2012, there were only three states that had over 100 cases of P&S syphilis among women aged 15–44 years; in 2021, 29 states reported over 100 cases.
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As in past years, there were significant disparities in rates of reported STDs. In 2021, half (50.5%) of reported cases of STDs were among adolescents and young adults aged 15–24 years. Disparities continue to persist in rates of reported STDs among some racial minority or Hispanic ethnicity groups when compared with rates among non-Hispanic White persons. In 2021, 31% of all cases of chlamydia, gonorrhea, and P&S syphilis were among non-Hispanic Black persons, even though they made up only approximately 12% of the US population.3 Although American Indian or Alaska Native persons contributed only 0.7% of all live births in the US, they made up 3.6% of all congenital syphilis cases. MSM are disproportionally impacted by STDs, including gonorrhea and P&S syphilis; further, almost 40% of MSM reported with P&S syphilis had been diagnosed with HIV.
It is important to note that these disparities are unlikely explained by differences in sexual behavior and rather reflect differential access to quality sexual health care, as well as differences in sexual network characteristics. For example, in communities with higher prevalence of STDs, with each sexual encounter, people face a greater chance of encountering an infected partner than those in lower prevalence settings do, regardless of similar sexual behavior patterns. Acknowledging inequities in STD rates is a critical first step toward empowering affected groups and the public health community, to collaborate in addressing systemic inequities in the burden of disease — with the ultimate goal of minimizing the health impacts of STDs on individuals and populations.
- National Academies of Sciences, Engineering, and Medicine 2021. Sexually Transmitted Infections: Adopting a Sexual Health Paradigm. Washington, DC: The National Academies Press. https://doi.org/10.17226/25955
- St. Cyr S, Barbee L, Workowski KA, et al. Update to CDC’s Treatment Guidelines for Gonococcal Infection, 2020. MMWR Morb Mortal Wkly Rep 2020;69:1911–1916. DOI: http://dx.doi.org/10.15585/mmwr.mm6950a6
- US Department of Health and Human Services. Office of Minority Health. Profile: Black/African Americans. Available at: https://minorityhealth.hhs.gov/omh/browse.aspx?lvl=3&lvlid=61