Frequent antiviral treatment failure in hepatitis C subtype 4r

From the French National Reference Center, 537 patients who
failed directly acting antiviral treatment (DAA) were identified
from 2015 – 2018. 121 (22.5 %) were infected with genotype 4
and 27 (22.3 %) of patients with genotype 4 were infected with
subtype 4r. Subtype 4r is rarely found in high income countries
and is overrepresented among failing patients. At treatment
failure, all subtype 4r harbored two to three NS5A resistance
associated substitutions (RASs). The most prevalent RASs
were L28/C/ /V and L30R. The authors suggest that all subtype
4r should be treated with triple DAAs to decrease the risk of
treatment failure and resistance development.

Ref; Fourati 2019;69:513-523

Comment: Subtype 4r is rarely found in high income countries
but is much more prevalent in the Middle East and parts of
Africa. The incidence of subtype 4 in general is increasing in
Europe and one cannot exclude that the proportion of subtype
4r is also increasing especially among migrants.