Introduction
In Hungary, the HUN-VE 3 study determined the comparative effectiveness of various
primary and booster vaccination strategies during the Delta COVID-19 wave. That study
included more than 8 million 18-100-year-old individuals from the beginning of the
pandemic. Immunocompromised (IC) individuals have increased risk for COVID-19 and
disease course might be more severe in them. In this study, we wished to estimate
the risk of SARS-CoV-2 infection and COVID-19 related death in IC individuals compared
to healthy ones and the effectiveness of the BNT162b2 vaccine by reassessing HUN-VE
3 data.
Patients and methods
Among the 8,087,988 individuals undergoing follow-up from the onset of the pandemic
in the HUN-VE 3 cohort, we selected all the 263,116 patients with a diagnosis corresponding
with IC and 6,128,518 controls from the second wave, before vaccinations started.
The IC state was defined as two occurrences of corresponding ICD-10 codes in outpatient
or inpatient claims data since 1 January, 2013. The control group included patients
without chronic diseases. The data about vaccination, SARS-CoV-2 infection and COVID-19
related death were obtained from the National Public Health Center (NPHC) during the
Delta wave. Cases of SARS-CoV-2 infection were reported on a daily basis using a centralized
system via the National Public Health Center (NPHC).
Results
Out of the 263,116 IC patients 12,055 patients (4.58%) and out of the 6,128,518 healthy
controls 202,163 (3.30%) acquired SARS-CoV-2 infection. Altogether 436 IC patients
and 2141 healthy controls died in relation to COVID-19. The crude incidence rate ratio
(IRR) of SARS-CoV-2 infection was 1.40 (95%CI: 1.37-1.42) comparing IC patients to
healthy controls. The crude mortality rate ratio was 4.75 (95%CI: 4.28-5.27). With
respect to SARS-CoV-2 infection, interestingly, the BNT162b2 vaccine was more effective
in IC patients compared to controls. Primary vaccine effectiveness (VE) was higher
in IC patients compared to controls and the booster restored VE after waning. VE regarding
COVID-19 related death was less in IC patients compared to healthy individuals. Booster
vaccination increased VE against COVID-19-related death in both IC patients and healthy
controls.
Conclusion
There is increased risk of SARS-CoV-2 infection and COVID-19 related mortality in
IC patient. Moreover, booster vaccination using BNT162b2 might restore impaired VE
in these individuals.
