Related Factors of Syphilis Positive Rate in Blood Donors During the COVID-19 Epidemic.

Background: In Shenzhen of China, the continuous increase of syphilis infections threatens the safety of blood transfusion. In 2020, COVID-19 was discovered and spread rapidly around the world, and affected the prevalence of syphilis among blood donors.

Methods: From 2013 to 2020, there were 839,161 blood samples collected in the Shenzhen Blood Center. Blood samples were screened by ELISA tests and confirmed by the TPPA (Treponema pallidum particle agglutination) tests and the TRUST (toluidine red unheated serum tests). All data was analyzed by the chi-square test.

Results: From 2013 to 2020, the positive rate of syphilis among blood donors varied significantly among individuals in different ages, educational backgrounds, regions, and blood donation histories (P<0.001). In 2020, It was the first time that there were more repeat blood donors than first-time blood donors and more blood donors with a higher education level than those with a lower education level, and the lowest reactive and positive rate of syphilis among blood donors was observed. Compared to 2019, the prevalence of syphilis among female and repeat blood donors decreased significantly in 2020 (P<0.01).

Conclusion: The prevalence of syphilis in blood donors is related to the characteristics of blood donors (in addition to gender) and the COVID-19 epidemic. COVID-19 can affect the prevalence of syphilis among blood donors by influencing the composition of blood donors and the number of syphile-positive donors in certain blood donors, including female and repeat blood donors.