Breakthrough severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections have been found in a small percentage of fully vaccinated individuals in the United States (US). Understanding the proportion of breakthrough infections is important as it informs public health policies and decisions related to primary dosing and booster doses of vaccines.
Study: COVID-19 infections post-vaccination by HIV status in the United States. Image Credit: FRstudio/Shutterstock
This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources
Breakthrough infections in immunocompromised patients
Compared to the general population, immunocompromised individuals such as people with HIV (PWH) are at an increased risk of breakthrough infections and may benefit from an extra vaccine dose against SARS-CoV-2 infection.
In the past, two observational research studies had compared the breakthrough infection rate between PWH and people without HIV (PWoH). These studies were limited because they did not categorize the differences in the outbreak rate by vaccine type or account for the HIV suppression or CD4 count.
The US Centers for Disease Control (CDC) has vaccination guidelines for PWH with untreated or advanced disease, which recommends an additional primary dose after 28 days of the second dose and a booster dose of the Moderna and Pfizer vaccines or a booster dose of any vaccine after two months. However, the CDC guidelines did not have a recommendation for PWH with viral suppression or partially recovered CD4 counts.
About the study
A recent study published in the preprint server medRxiv* aimed to identify the risk of breakthrough coronavirus disease 2019 (COVID-19) infection in fully vaccinated PWH and PWoH in the US, based on the HIV status.
The data for the study was collected from the Corona-Infectious-Virus Epidemiology Team (CIVET)-II cohort, which has four cohorts with data on PWH from the integrated health systems and academic health centers. These cohorts covered various geographical areas in the US and the data were derived from electronic medical records.
The CIVET-II cohort comprised individuals above 18 years of age who have completed their immunization against COVID-19 between December 11, 2020, and June 30, 2021. Each PWH was matched with three PWoH on parameters such as the date on which they completed their vaccination, 10-year age groups, sex at birth, and ethnicity.
The Veterans Aging Cohort Study (VACS) participants were not matched on the date of their vaccination. Using HIV status and vaccine type, incidence rates and 95% confidence interval were calculated per 1,000 PY. The Cox proportional hazards model was used to determine the adjusted hazard ratio of COVID-19 breakthrough based on HIV status.
Results
The study population included 109,599 individuals after excluding 120 patients who received mix vaccine types during the primary vaccination. The majority of the patients were non-Hispanic Black males aged 55 years or older and received Pfizer (51%) or Moderna (43%) vaccines. Only 6% of the participants had received the J&J vaccine.
After the initial series, 26% of PWH received an extra COVID-19 vaccination dose, compared to only 12% of PWoH. Prior to immunization, 15% of PWH had AIDS and, at the time of complete immunization, 88% were virally suppressed with a median CD4 count of 622 cells/mm3.
The incidence of breakthrough infection was higher in the PWH group (44 per 1,000 PY) compared to PWoH (31 per 1,000 PY). In PWH, the rate of breakthrough infections was most associated with the J&J vaccine (59 per 1,000 PY), followed by Pfizer (40 per 1,000 PY), and Moderna (26 per 1,000 PY) vaccines.
The cumulative incidence of breakthrough infections at 210 days after completing the two-dose vaccination regimen was higher in PWH (2.8%) versus PWoH (2.1%). PWH with low CD4 counts and high viral load had a higher risk of cumulative incidence of breakthrough infection, although it was not statistically significant.
Older individuals (55-74 years) in PWH had a decreased risk of breakthrough infection whereas younger participants (18-24 years) had an increased risk. Notably, the risk of breakthrough infection increased during the emergence of the Delta variant in July-September 2021. Those with prior COVID-19 infection had a three-fold increase in breakthrough infection.
Conclusions
The study results showed a 41% greater incidence of breakthrough infections in PWH compared to that in PWoH. These findings are consistent with previous study reports on immunodeficiency disorders increasing the likelihood of COVID-19 outbreaks. Despite the recovery in CD4 count, PWH can still have immune dysfunction.
The findings may not apply to all PWH in the US as it only accounted for those with access to care. The observations of this study highlight the importance of an immediate booster dose for PWH who received the J&J vaccine, preferably initiating a two-dose mRNA vaccine regimen.
According to the authors, since PWH had a higher chance of developing breakthrough infections in comparison to PWoH, all PWH should be included in the CDC’s additional vaccine dose recommendations.
This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources
Article Revisions
- May 9 2023 - The preprint preliminary research paper that this article was based upon was accepted for publication in a peer-reviewed Scientific Journal. This article was edited accordingly to include a link to the final peer-reviewed paper, now shown in the sources section.
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