Presymptomatic viral shedding in high‐risk mpox contacts: A prospective cohort study

Abstract

The risk of infection after exposure to clade IIb mpox virus (MPXV) is unknown, and potential presymptomatic shedding of MPXV remains to be demonstrated. High-risk contacts of mpox patients were followed-up in a prospective longitudinal cohort study. Individuals reporting sexual contact, >15 min skin-to-skin contact, or living in the same household with an mpox patient were recruited in a sexual health clinic in Antwerp, Belgium. Participants kept a symptom diary, performed daily self-sampling (anorectal, genital, and saliva), and presented for weekly clinic visits for physical examination and sampling (blood and oropharyngeal). Samples were tested for MPXV by PCR. Between June 24 and July 31, 2022, 25 contacts were included, of which 12/18 (66.0%) sexual and 1/7 (14.0%) nonsexual contacts showed evidence of infection by MPXV-PCR. Six cases had typical mpox symptoms. Viral DNA was detected as early as 4 days before symptom onset in 5 of them. In 3 of these cases, replication-competent virus was demonstrated in the presymptomatic phase. These findings confirm the existence of presymptomatic shedding of replication-competent MPXV and emphasize the high risk of transmission during sexual contact. Sexual contacts of mpox cases should abstain from sex during the incubation period, irrespective of symptoms.

The Durability and Avidity of MPXV-specific Antibodies Induced by the Two-dose MVA-BN Mpox Vaccine

“…The average mpox incubation period of just over a week 39 may be short enough that memory B cells and memory T cells can activate and protect an exposed human even in the absence of circulating neutralizing antibodies. How waning of antibodies impacts transmission is also an open question as recent work has revealed that viral DNA and culturable virus is present in infected individuals as early as 4 days prior to symptom onset 40 . Our finding here that a longer dosing interval increases neutralizing titer durability among naïve vaccinees differs from our previous work where we reported that there was no significant effect of interval on durability of anti-MPXV H3 IgG titers in naïve individuals 7 .…”

Modeling the impact of prioritizing first or second vaccine doses during the 2022 mpox outbreak

“…We used an SEIR (susceptible, exposed, infectious, resistant) natural history in our model, expanded to account for pre-symptomatic transmission and multi-dose vaccination [6]. Individuals start in the susceptible ( S ) class.…”

Lack of monkeypox virus (MPXV) transmission despite occupational exposure of a large number of health care workers

“…5,6 Furthermore, presymptomatic (1−4 days before symptom onset) viral shedding of replication-competent MPXV has been reported. 7 In experimental settings, MPX-virions could be recovered from stainless steel for several days, but were efficiently inactivated by alcohol-or aldehyde-based surface disinfectants. 8 In hospital settings, environmental surface contamination with high MPXV-loads and cultivatable virus was shown on surfaces of rooms occupied by Mpox patients.…”