HIV-positive patients had a similar outcome to HIV-negative patients during the 2009/10 swine flu pandemic, Spanish researchers report in the online edition of AIDS.
Rates of secondary pneumonia, admission to intensive care, the use of mechanical ventilation and mortality were similarly low in both groups of patients.
Patients with HIV did not take any longer to recover from the infection, and did not require a longer stay in hospital.
The investigators describe these findings as “remarkable”.
In June 2009, the World Health Organization (WHO) issued an alert about a new strain of human influenza A in Mexico. Called H1N1, the virus originated in pigs, hence its popular name, swine flu.
Unlike seasonal flu outbreaks, it appeared that younger adults had an increased risk of developing swine flu-related complications. This was also the case for patients with underlying medical conditions, including those caused by immunosuppression.
Therefore, patients with HIV were one of the groups prioritised to receive vaccination against the infection.
Despite this recommendation little is known about the outcome of HIV-positive patients who contracted swine flu. Only one fatality in an HIV-positive patient with the infection has so far been reported.
Therefore investigators undertook a prospective study in order to describe the symptoms, complications and outcomes of swine flu in HIV-positive patients who were admitted to 13 hospitals in Spain between June and November 2009. The characteristics of these HIV-positive patients were compared to HIV-negative swine flu patients to see if outcomes differed between these two groups.
A total of 585 patients with confirmed H1N1 infection were included in the investigators’ analysis. Of these patients, 26 were HIV-positive.
Age (43 vs 40 years), sex (69% vs 50% male) and pregnancy status (12% vs 35%) were similar between the HIV-positive and HIV-negative patients.
Those with HIV were more likely to smoke (54% vs 31%, p = 0.013). However, a higher proportion of HIV-infected patients had received the seasonal flu vaccine (56% vs 11%, p < 0.001), as well as the vaccine against pneumococcal pneumonia (50% vs 3%, p < 0.001).
Other than liver failure (31% vs 4%, p < 0.001) patients with HIV were no more likely to have other serious underlying health conditions.
Most (89%) of the HIV-positive patients were taking antiretroviral therapy, their median CD4 cell count was 503 cells/mm3, and 84% had an undetectable viral load.
There was no difference between the two groups of patients between the types of swine flu symptoms reported and the interval between the appearance of symptoms and admission to hospital.
With the exception of thrombocytopenia (p = 0.002), HIV-positive patients did not have a higher rate of laboratory abnormalities than those who were HIV-negative.
Chest X-ray results were abnormal in 50% of patients with HIV and 42% of HIV-negative patients. Secondary bacterial pneumonia developed in 12% vs 8% of patients.
Virtually all the patients received antiviral flu therapy. However, overall only 36% of patients started this therapy within the recommended 48 hours of the onset of symptoms.
Antibiotics were provided to 80% of HIV-positive patients and 72% of HIV-negative individuals. The mean duration of therapy was 9 vs 8 days.
There was no evidence that swine flu was more severe in patients with HIV. Outcomes were similar, irrespective of HIV status.
Both groups of patients started to improve an average of 2.5 days after their admission to hospital. The duration of the stay in hospital was similar for the two groups: 6 days for those with HIV compared to 7 days for non-HIV patients.
Similar proportions of HIV-negative (12%) and HIV-positive (12%) patients were admitted to intensive care and required mechanical ventilation (8% vs 9%).
None of the HIV-positive individuals died compared to 2% of the HIV-negative patients.
“The fact that no differences in clinical outcomes were observed between HIV-1-infected and seronegative patients is remarkable”, comment the investigators.
They conclude, “in HIV patients, well controlled on HAART, the new influenza virus AH1N1 had similar clinical outcomes and prognosis to non-HIV patients.”
Riera M et al. Clinical presentation and prognosis of the 2009 H1N1 influenza A infection in HIV-1-infected patients: a Spanish multicenter study. AIDS 24, advance online publication, September 4, 2010. DOI: 10. 1097/QAD.0bo13e32833e508f. (Link to abstract and full-text publication).