COVID-19, HIV, and Syphilis Contact Tracing: What Have We Learned and Where Are We Headed?

ABSTRACT: Contact tracing is a core public health intervention for a range of communicable diseases, in which the primary goal is to interrupt disease transmission and decrease morbidity. In this article, we present lessons learned from COVID-19, HIV, and syphilis in San Francisco to illustrate factors that shape the effectiveness of contact tracing programs and to highlight the value of investing in a robust disease intervention workforce with capacity to pivot rapidly in response to a range of emerging disease trends and outbreak response needs.

Effectiveness of Syphilis Partner Notification After Adjusting for Treatment Dates, 7 Jurisdictions.

BACKGROUND: Disease intervention specialists (DIS) prevent syphilis by ensuring treatment for patients' sex partners through partner notification (PN). Different interpretations of how to measure partners treated due to DIS efforts complicates PN evaluation. We measured PN impact by counting partners treated for syphilis after DIS interviewed the patient. METHODS: We reviewed data from early syphilis cases reported during the 2015-2017 period in 7 jurisdictions. We compared infected partners brought to treatment using the following: (1) DIS-assigned disposition codes or (2) all infected partners treated 0 to 90 days after the patient's interview (adjusted treatment estimate). Stratified analyses assessed patient characteristics associated with the adjusted treatment estimate. RESULTS: Disease intervention specialists interviewed 23,613 patients who reported 20,890 partners with locating information. Many of the 3569 (17.1%) partners classified by DIS as brought to treatment were treated before the patient was interviewed. There were 2359 (11.3%) partners treated 0 to 90 days after the patient's interview. Treatment estimates were more consistent between programs when measured using our adjusted estimates (range, 6.1%-14.8% per patient interviewed) compared with DIS-assigned disposition (range, 6.1%-28.3%). Treatment for ≥1 partner occurred after 9.0% of interviews and was more likely if the patient was a woman (17.9%), younger than 25 years (12.6%), interviewed ≤7 days from diagnosis (13.9%), HIV negative (12.6%), or had no reported history of syphilis (9.8%). CONCLUSIONS: Counting infected partners treated 0 to 90 days after interview reduced variability in reporting and facilitates quality assurance. Identifying programs and DIS who are particularly good at finding and treating partners could improve program impact.

Contact-Tracing Outcomes Among Household Contacts of Fully Vaccinated Coronavirus Disease 2019 (COVID-19) Patients: San Francisco, California, 29 January-2 July 2021.

BACKGROUND: The extent to which vaccinated persons diagnosed with coronavirus disease 2019 (COVID-19) can transmit to other vaccinated and unvaccinated persons is unclear. METHODS: Using data from the San Francisco Department of Public Health, this report describes outcomes of household contact tracing during 29 January-2 July 2021, where fully vaccinated patients with COVID-19 were the index case in the household. RESULTS: Among 248 fully vaccinated patients with breakthrough infections, 203 (82%) were symptomatic and 105 were identified as the index patient within their household. Among 179 named household contacts, 71 (40%) contacts tested, over half (56%) were fully vaccinated and the secondary attack rate was 28%. Overall transmission from a symptomatic fully vaccinated patient with breakthrough infection to household contacts was suspected in 14 of 105 (13%) of households. Viral genomic sequencing of samples from 44% of fully vaccinated patients showed that 82% of those sequenced were infected by a variant of concern or interest and 77% by a variant carrying mutation(s) associated with resistance to neutralizing antibodies. CONCLUSIONS: Transmission from fully vaccinated symptomatic index patients to vaccinated and unvaccinated household contacts can occur. Indoor face masking and timely testing of all household contacts should be considered when a household member receives a positive test result in order to identify and interrupt transmission chains.

Characteristics Associated With Delivery of an Infant With Congenital Syphilis and Missed Opportunities for Prevention-California, 2012 to 2014.

BACKGROUND: Congenital syphilis (CS), the transmission of Treponema pallidum from mother to fetus during pregnancy, can cause adverse birth outcomes. In 2012 to 2014, the CS rate in California increased more than 200% from 6.6 to 20.3 cases per 100,000 live births. Our objectives were to identify characteristics associated with delivering an infant with CS and missed opportunities for prevention among syphilis-infected pregnant women in California. METHODS: We linked California Department of Public Health syphilis surveillance records from women aged 15 to 45 years-diagnosed from March 13, 2012, to December 31, 2014-to birth records. We compared characteristics among mothers who delivered an infant with CS (CS mothers) with mothers who delivered an infant without CS (non-CS mothers) by using χ or Fisher exact tests. To visualize gaps in prevention among syphilis-infected pregnant women, we constructed a CS prevention cascade, a figure that shows steps to prevent CS. RESULTS: During the selected period, 2498 women were diagnosed as having syphilis, and 427 (17%) linked to birth records; 164 (38%) were defined as CS mothers and 263 (62%) as non-CS mothers. Mothers with CS were more likely than non-CS mothers to have their first prenatal care visit in the third trimester. High proportions of mothers in both groups reported high-risk sexual behaviors, methamphetamine use, or incarceration (13%-29%). The CS prevention cascade showed decrements of 5% to 11% in prenatal care receipt, testing, and treatment steps; only 62% of potential CS births were prevented. CONCLUSIONS: Multifaceted efforts are needed to address gaps in the CS prevention cascade and reduce CS cases in California.

Impact of social network characteristics on shelter use among street youth in San Francisco.

PURPOSE: We examined the cross-sectional and longitudinal association between social network characteristics and street youths' shelter use, a determinant of health outcomes for homeless youth. METHODS: We analyzed interview data from 138 street youth recruited through venue-based sampling in San Francisco, to assess the cross-sectional relationship between shelter use in youths' social networks and youths' reported shelter use. We also assessed the relationship between baseline network shelter use and shelter use at 6-month follow-up. RESULTS: Low proportions of street youth reported shelter use at baseline (38%) and follow-up (29.6%). Twenty-nine (26.9%) youth were in networks with shelter users at baseline, compared with 17 youth (15.7%) at follow-up. In cross-sectional analysis, youth in networks with shelter users had 5-fold increased odds of reporting shelter use (OR: 5.86, p = .006). A 1-person increase in the number of network shelter users was associated with 2-fold increased odds of youths' shelter use (OR: 2.16, p = .02). In longitudinal analysis, youth in networks with shelter users at baseline had nearly 5-fold increased odds of shelter use at follow-up (OR: 4.95, p = .01). A 1-person increase in the number of network shelter users at baseline was associated with 3-fold increased odds of shelter use at follow-up (OR: 3.15, p = .004). CONCLUSION: Shelter users seem to cluster together. Shelter use by extended network members was associated with increased odds of youths' own shelter use. Understanding how network behaviors influence street youths' health-related behaviors, such as shelter use, could inform network-based interventions encouraging service uptake among marginalized and hard-to-reach street youth populations.

Sex, drugs (methamphetamines), and the Internet: increasing syphilis among men who have sex with men in California, 2004-2008.

OBJECTIVES: We examined primary and secondary syphilis cases among men who have sex with men (MSM) in California, and the association of methamphetamine use and Internet use to meet sex partners (Internet use) with number of sex partners. METHODS: We analyzed California surveillance data for MSM who were diagnosed with syphilis between 2004 and 2008, to assess differences in the mean number of sex partners by methamphetamine use and mutually exclusive groups of patients reporting Internet use (Internet users). RESULTS: Large proportions of patients reported methamphetamine use (19.2%) and Internet use (36.4%). From 2006 through 2008, Adam4Adam was the most frequently reported Web site statewide, despite temporal and regional differences in Web site usage. Methamphetamine users reported more sex partners (mean = 11.7) than nonmethamphetamine users (mean = 5.6; P < .001). Internet users reported more sex partners (mean = 9.8) than non-Internet users (mean = 5.0; P < .001). Multivariable analysis of variance confirmed an independent association of methamphetamine and Internet use with increased numbers of sex partners. CONCLUSIONS: Higher numbers of partners among MSM syphilis patients were associated with methamphetamine and Internet use. Collaboration between currently stand-alone interventions targeting methamphetamine users and Internet users may offer potential advances in sexually transmitted disease control efforts.

Repeat syphilis among men who have sex with men in California, 2002-2006: implications for syphilis elimination efforts.

OBJECTIVES: We examined rates of and risk factors for repeat syphilis infection among men who have sex with men (MSM) in California. METHODS: We analyzed 2002 to 2006 California syphilis surveillance system data. RESULTS: During the study period, a mean of 5.9% (range: 4.9%-7.1% per year) of MSM had a repeat primary or secondary (PS) syphilis infection within 2 years of an initial infection. There was no significant increase in the annual proportion of MSM with a repeat syphilis infection (P = .42). In a multivariable model, factors associated with repeat syphilis infection were HIV infection (odds ratio [OR] = 1.65; 95% confidence interval [CI] = 1.14, 2.37), Black race (OR = 1.84; 95% CI = 1.12, 3.04), and 10 or more recent sex partners (OR = 1.99; 95% CI = 1.12, 3.50). CONCLUSIONS: Approximately 6% of MSM in California have a repeat PS syphilis infection within 2 years of an initial infection. HIV infection, Black race, and having multiple sex partners are associated with increased odds of repeat infection. Syphilis elimination efforts should include messages about the risk for repeat infection and the importance of follow-up testing. Public health attention to individuals repeatedly infected with syphilis may help reduce local disease burdens.