Immunogenicity and Effectiveness of Primary and Booster Vaccine Combination Strategies during Periods of SARS-CoV-2 Delta and Omicron Variants

Rima Moghnieh; Claude El Hajj; Dania Abdallah; Nayla Jbeily; Abdul Rahman Bizri; Mohamed H Sayegh

doi:10.3390/vaccines10101596

Immunogenicity and Effectiveness of Primary and Booster Vaccine Combination Strategies during Periods of SARS-CoV-2 Delta and Omicron Variants

Vaccines (Basel). 2022 Sep 22;10(10):1596. doi: 10.3390/vaccines10101596.

Authors

Rima Moghnieh^{1

2}, Claude El Hajj^{2

3}, Dania Abdallah⁴, Nayla Jbeily⁵, Abdul Rahman Bizri⁶, Mohamed H Sayegh^{7

8}

Affiliations

¹ Division of Infectious Diseases, Department of Internal Medicine, Makassed General Hospital, Beirut P.O. Box 11-6301, Lebanon.
² Faculty of Medicine, Lebanese University, Beirut P.O. Box 6573/14, Lebanon.
³ Middle East Airlines-AIRLIBAN S.A.L., Beirut P.O. Box 206, Lebanon.
⁴ Pharmacy Department, Makassed General Hospital, Beirut P.O. Box 11-6301, Lebanon.
⁵ FMPS Holding S.A.L., Beirut P.O. Box 60 247, Lebanon.
⁶ Department of Internal Medicine, Division of Infectious Diseases, American University of Beirut Medical Center, Beirut P.O. Box 11-0236, Lebanon.
⁷ GAP Solutions under Contract No. 75N93019D00026 with National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, United States of America, Washington, DC 20201, USA.
⁸ Faculty of Medicine, American University of Beirut, Beirut P.O. Box 11-0236, Lebanon.

Abstract

In this study involving a cohort of employees of the National Airline company in Lebanon, we assessed humoral immunity levels and the effectiveness of two COVID-19 vaccines, Gam-COVID-Vac versus BNT162b2, after two doses and after a homologous and heterologous BNT162b2 booster, in addition to the impact of hybrid immunity. Vaccine effectiveness (VE) was retrospectively determined against laboratory-confirmed SARS-CoV-2 infection during the periods of Delta and Omicron variants' predominance, separately, and was calculated based on a case-control study design. The humoral immune response, measured by a SARS-CoV-2 anti-spike receptor-binding domain (RBD) IgG titer, was prospectively assessed after the aforementioned vaccination schemes at different time points. This study showed higher effectiveness of BNT162b2 after two doses (81%) compared to two doses of Gam-COVID-Vac (41.8%) against the Delta variant of SARS-CoV-2, which correlated with anti-spike antibody levels. Regarding the Omicron variant, protection against infection and antibody levels were severely compromised and the correlation between an anti-spike IgG titer and effectiveness was lost, unlike the situation during the Delta wave. Considering the booster vaccination schemes, a homologous BNT162b2 booster after a BNT162b2 primary vaccination induced a higher humoral immune response when compared to that induced by a heterologous BNT162b2 booster after a Gam-COVID-Vac primary vaccination. However, the VE of both booster regimens against the Omicron variant was almost equal (64% in the homologous regimen and 57% in heterologous regimen). Hybrid immunity evidenced a better humoral response and a greater and longer protection against Delta and Omicron infections compared to vaccination-induced immunity in COVID-19-naïve individuals. Finally, the findings show that VE waned with time during the same wave, highlighting the importance of reinforcing primary and booster COVID-19 vaccination mainly at the beginning of each wave during the surge of a new variant of concern.

Keywords: BNT162b2; Delta variant; Gam-COVID-Vac; Lebanon; Omicron variant; effectiveness; heterologous vaccination; homologous vaccination; immunogenicity.

Grants and funding

This work was supported and funded by Mohamad El Hout, Chairman-Director General of Middle East Airlines.