HIV increases risk of severe COVID-19 in largest US study

Simon Collins, HIV i-Base

The largest national US cohort study so far, reports that people living with HIV have significantly higher risks of more severe COVID-19 and that these risks increase further with lower CD4 counts and higher viral load.

The analysis included almost 1.5 million people diagnosed with COVID-19 from January 2020 to May 2021. It looked at outcomes in more than 8,200 people living with HIV and more than 11,300 who had a solid organ transplant (SOT) (and 267 with both) and used multivariate analyses that also adjusted for demographics, medical and social factors. Severity of outcome used a 5-point scale, including hospitalisation, invasive ventilation, and death.

The paper, not yet peer-reviewed was published on 28 July 2021.

Baseline demographics for the cohort included median age 47 (IQR: 32 to 61), 55% were female, 52% were non-Hispanic white, 13% were non-Hispanic black, and 16% were current or former smokers.

People who were HIV positive and those with SOT were more likely to be older, male, non-Hispanic Black, and have more comorbid conditions (all p<0.01).

Overall results reported significantly increased risk of more severe COVID-19 for both groups, compared to people without immune dysfunction (all p<0.01). See Table 1.

Within the HIV positive group, lower CD4 count and higher viral load increased the risk of all outcomes. See Table 2.

For people with undetectable viral load on ART, having a lower CD4 count of 350 to 500 and <350 cells/mm3 was associated with 2.9- and 6-fold increased odds of hospitalisaton, respectively, compared to those with CD4 counts >500.

Similarly, among people with a high CD4 count (>500 cells/mm3), detectable viral load independently had a 2-fold increased risk of hospitalisation.

Table 1: Summary of risk of severe COVID-19 for HIV and SOT *

Hospitalisation 1.28 (1.27 to 1.29) 2.61 (2.58 to 2.65)
Invasive ventilation 1.43 (1.43 to 1.43) 4.82 (4.78 to 4.86)
Death 1.20 (1.19 to 1.20) 3.38 (3.35 to 3.41)

* adjusted odds ratio (95%CI), including for sociodemographics and comorbidities.

Table 2: Impact of CD4 and viral load on risk of severe COVID-19 *

CD4 <350 VL 50 to <1000 VL >1000
Hospitalisation 4.4 (3.6 to 5.3) 1.8 (1.2 to 2.7) 3.5 (2.2 to 5.5)
invasive ventilation 5.4 (3.2 to 9.0)
Death 7.6 (3.9 to 14.9) 4.4 (1.4 to 13.7) 7.3 (2.1 to 25.7)

* Odds ratio compared to CD4 >500 and undetectable viral load


Although not yet peer-reviewed, this is the largest study to include such comprehensive CD4 count and viral load data.

The clear associations with more severe COVID-19 over the first 17 months of the epidemic convincingly overcome the earlier concerns with smaller studies that reported no link.

The results show the importance of including HIV as a criteria for priority access to vaccines. They also show the importance of greater care to reduce risk of transmission, especially as lock down measures are being relaxed and Delta variant is so dominant.

The CD4 and viral load results show the importance of being on effective ART, but that this still does not normalise risk compared to being HIV negative.


Sun J et al. COVID-19 disease severity among people with HIV infection or solid organ transplant in the united states: a nationally- representative, multicenter, observational cohort study. medRxiv 2021.07.26.21261028; doi: 10.1101/2021.07.26.21261028. (28 July 2021).

This article was first published on 3 August 2021.

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