Despite decline in HSV-2, nearly 20 million new infections still expected by 2050 in US
Despite a decline in herpes simplex virus type 2 infections over the course of decades, researchers calculated that more than 600,000 new infections will still occur every year in the U.S., leading to almost 20 million new cases by 2050.
The researchers used modeling and national health data to characterize the “evolving epidemiology” of the HSV-2 epidemic in the U.S. from 1950 to 2050 and found that it “underwent a major transition over a century, leading to two distinct experiences for two generations.”
“From 1950 to mid-1980s, the epidemic expanded massively to add 30 million new infections and to affect nearly a quarter of the U.S. population,” they wrote in Open Forum Infectious Diseases. “From mid-1980s, however, the epidemic reversed course with rapid declines, followed by stabilization that is projected to continue over the next 3 decades.”
“[This study was prompted by] the need to assess HSV-2 infection levels in the U.S. to understand the epidemiology of this infection, number of current and future infections, and the need to develop an HSV-2 vaccine,” Houssein H. Ayoub, PhD, assistant professor of mathematics, statistics and physics at Qatar University, and Laith Jamal Abu Raddad, PhD, professor of population health sciences at Weill Cornell Medical College, Cornell University, told Healio.
According to the study, antibody prevalence increases rapidly from 1960 peaking at 19.9% in 1983 in those aged 15 to 49 years before reversing to a decline to 13.2% by 2020 and 8.5% by 2050. The study showed that the incidence rate peaked in 1971 at 11.9 per 1,000 person-years, declined by 59% by 2020 and 70% by 2050. Additionally, the annual number of new infections peaked at 1,033,000 in 1978, before declining to 667,000 by 2020 and 600,000 by 2050. Based on these numbers, the study demonstrated that women were disproportionately affected, averaging around 75% higher seroprevalence, a 95% higher incidence rate and a 71% higher annual number of infections. However, in 2020, 78% of infections were acquired by individuals aged 15 to 34 years old.
According to Houssein and Raddad, the findings highlight the scale of HSV-2 burden in the U.S. and demonstrate the need for continuous surveillance and to develop prophylactic and therapeutic HSV-2 vaccines.
“In this context, our study provides insights that will inform the development of the HSV-2 vaccine business case, currently led by WHO and global partners,” Houssein and Raddad said. “We need a vaccine for such an infection with high incidence and disease burden that is affecting tens of millions of Americans.”