• Sally Mahmoud, Subhashini Ganesan, Sharif-AskariNarjes SahebNS0000-0003-0482-6777College of Medicine, University of Sharjah, Sharjah, UAE., Flavia Cantarutti, Hannah Wilson, Pauline Ogrodzki, Rabih Halwani, Nawal Alkaabi, and Walid Abbas Zaher.
• Biogenix Lab, Abu Dhabi, UAE.
• Curr Med Res Opin. 2022 Dec 1; 38 (12): 206920752069-2075.

BackgroundBreakthrough infections post-COVID-19 vaccination occur with the emerging variants of the SARS-CoV virus which might be either due to the newer variants escaping immune response or the waning of antibodies over time. However, there is lack of long-term follow-up evidence on the waning of immune response following inactivated COVID-19 vaccine.MethodsA retrospective, observational study was conducted on serum samples of individuals who had received two doses of BBIBP-CorV vaccine. Individual's antibody responses were evaluated based on IgG anti-S and neutralizing antibodies measurements. Antibody samples were categorized into four groups, defined by the time interval from the individual's receipt of the BBIBP-CorV vaccine: <30 days, 30-90 days, 91-180 days and >180 days.ResultsA total of 6668 serum samples from inactivated BBIBP-CorV vaccine recipients were analyzed for IgG anti-S and neutralizing antibodies. 571 (8.6%) samples were tested during the first 29 days interval post vaccination, 3642 (54.6%) were tested during 30-90 days interval, 2173 (32.6%) samples were tested during 91 to 180 days interval and 282(4.2%) were tested at >180 days interval post vaccination. We found that more than 50% of the individuals had antibody titers below the average cut-off range at the 91-180 days interval post vaccination. Older age (>60 years), male gender, chronic kidney disease, hypertension, immunodeficiencies and increased interval post vaccination emerged as independent risk factors associated with lower immune response.ConclusionInactivated BBIBP-CorV vaccine recipients, based on age, gender and associated comorbid conditions might need booster doses at an earlier interval than the currently followed six months interval.

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