Influenza Viral Shedding in a Prospective Cohort of HIV-Infected and Uninfected Children and Adults in 2 Provinces of South Africa, 2012-2014

Abstract

Background: Prolonged shedding of influenza viruses may be associated with increased transmissibility and resistance mutation acquisition due to therapy. We compared duration and magnitude of influenza shedding between human immunodeficiency virus (HIV)-infected and -uninfected individuals.

Methods: A prospective cohort study during 3 influenza seasons enrolled patients with influenza-like illness and a positive influenza rapid test. Influenza viruses were detected by real-time reverse transcription polymerase chain reaction. Weibull accelerated failure time regression models were used to describe influenza virus shedding. Mann-Whitney U tests explored initial influenza viral loads (VL).

Results: Influenza virus shedding duration was similar in 65 HIV-infected (6 days; interquartile range [IQR] 3-10) and 176 HIV-uninfected individuals (7 days; IQR 4-11; P = .97), as was initial influenza VL (HIV-uninfected 5.28 ± 1.33 log10 copies/mL, HIV-infected 4.73 ± 1.68 log10 copies/mL; P = .08). Adjusted for age, HIV-infected individuals with low CD4 counts shed influenza virus for longer than those with higher counts (adjusted hazard ratio 3.55; 95% confidence interval, 1.05-12.08).

Discussion: A longer duration of influenza virus shedding in HIV-infected individuals with low CD4 counts may suggest a possible increased risk for transmission or viral evolution in severely immunocompromised individuals. HIV-infected individuals should be prioritized for annual influenza immunization.

Figure 1.

Patients with influenza-like illness (ILI) enrolled into the influenza shedding study, Klerksdorp and Edendale, South Africa, 2012–2014. *In 2012 participants were enrolled in Klerksdorp from May to October, while in Edendale enrolment only started in August following ethics approval. In 2013 and 2014, enrolment was from May to October at both sites. **Does not include patients who refused to participate in the ILI surveillance program or left before they were screened. Abbreviation: rRT-PCR, reverse transcription polymerase chain reaction.

Figure 2.

Kaplan-Meyer plots showing the probability of reverse transcription polymerase chain reaction-positive Influenza virus result by day after shedding onset by (A) human immunodeficiency virus (HIV) status, (B) age group, (C) influenza subtype, and (D) CD4 count.