Hybrid immunity versus vaccine-induced immunity against SARS CoV2 in Patients with Autoimmune Rheumatic Diseases

Introduction

Single-dose COVID-19 vaccines in healthy individuals with past COVID-19 infections seem to provide better immunity than double doses in COVID-19 unexposed individuals. However, it is not known whether the same is true for patients with autoimmune rheumatic diseases (AIRD) who are on immunosuppressants.

Methods

We identified 30 patients with AIRD who took a single dose of the ChAdOx1 vaccine post-COVID-19 infection. Age, sex and disease similar patients were enrolled in to three groups of 30 each who had (1) past infection with COVID-19 but no vaccine, (2) a single dose of ChAdOx1 and (3) double doses of ChAdOx1. Sera were collected from each patient approximately 30 days after last vaccine dose or since the onset of COVID19 symptoms (in the unvaccinated group). Antibodies to spike protein were estimated and virus neutralization potential of sera was tested.

Results

Baseline characteristics including drug usage was similar betweenthe groups. Seroconversion occurred in 25(83%), 23(77%), 27(90%), and 30(100%) in natural infection, single-dose vaccine, double dose vaccine, and infection +single dose vaccine groups respectively. Mean antibody titres (10076.8±8998) in the last group were at least 6-100x higher than in the other 3 groups. Also, the infection +vaccine group had the highest neutralization potential of 83.37 % as compared to 45.4% in the fully vaccinated group.

Conclusion

The hybrid immunity with a single dose of the vector-based vaccine post-infection seems to be superior to double dosage of the vaccine in patients with AIRD. A universal vaccination strategy involving a single dose of vaccine for all individuals with previous COVID-19 infection seems to be effective in these patients also.

What is already known about this subject?

A single dose of an RNA based COVID-19 vaccine after COVID-19 natural infection provides superior immune protection as compared to double doses of vaccines in infection naïve persons

A second dose of vaccine in healthy people who had infection previously does not increase the immune protection but may paradoxically induce tolerance

Vaccine responses in patients with autoimmune rheumatic diseases(AIRD) may be suboptimal due to underlying disease or the use of immunosuppressants.

What does this study add?

Hybrid-induced immunity (single vaccine post COVID-19 infection) produces adequate vaccine responses in patients with AIRD, non-inferior to double dose of vaccine

Besides mRNA vaccines, the adenoviral vector vaccine AZD1222 also demonstrates this hybrid phenomenon.

How might this impact on clinical practice?

Vaccination policies can consider providing only a single vaccine in those who had previous COVID-19 infection. This strategy has been shown not to be harmful for patients with AIRD. This will help reduce vaccine shortages.