Persistence of immune responses to the Sinopharm/BBIBP‐CorV vaccine

Abstract

Background To determine the kinetics and persistence of immune responses following the Sinopharm/BBIBP‐CorV, we investigated immune responses in a cohort of Sri Lankan individuals. Methods SARS‐CoV‐2 specific total antibodies were measured in 20–39 years ( n = 61), 40–59 years ( n = 120) and those >60 years of age ( n = 22) by enzyme‐linked immunosorbent assay, 12 weeks after the second dose of the vaccine. Angiotensin‐converting enzyme 2 (ACE2) receptor blocking antibodies (ACE2R‐Ab), antibodies to the receptor‐binding domain (RBD) of the ancestral virus (WT) and variants of concern, were measured in a sub cohort. T cell responses and memory B cell responses were assessed by ELISpot assays. Results A total of 193/203 (95.07%) of individuals had detectable SARS‐CoV‐2 specific total antibodies, while 67/110 (60.9%) had ACE2R‐Ab. A total of 14.3%–16.7% individuals in the 20–39 age groups had detectable antibodies to the RBD of the WT and variants of concern, while the positivity rates of those ≥60 years of age was <10%. A total of 14/49 (28.6%) had Interferon gamma ELISpot responses to overlapping peptides of the spike protein, while memory B cell responses were detected in 9/20 to the S1 recombinant protein. The total antibody levels and ACE2R‐Ab declined from 2 to 12 weeks from the second dose, while ex vivo T cell responses remained unchanged. The decline in ACE2R‐Ab levels was significant among the 40–59 ( p = .0007) and ≥60 ( p = .005) age groups. Conclusions Antibody responses declined in all age groups, especially in those ≥60 years, while T cell responses persisted. The effect of waning of immunity on hospitalization and severe disease should be assessed by long term efficacy studies.

Effect of age and prior COVID-19 on BBIBP-CorV (Sinopharm) vaccination- induced antibody responses in a region with high seroprevalence

“…Studies on immune response induced by BBIBP-CorV have shown differing results. In Sri Lanka, more than 90% seropositivity was observed was seen that 6 weeks post-vaccination [15,17]. A study from the United Arab Emirates showed seropositivity of 78% in the general population after full vaccination [18], with a similar result shown in a report from Pakistan [19].…”

“…It is particularly important to have data from high infectious disease burden regions with limited COVID-19 vaccine access and where primarily, inactivated vaccines were administered as humoral responses against SARS-CoV-2 are driven both by natural infection and COVID-19 vaccinations [20][21][22][23]. High seropositivity rates following natural infection have been associated with high population densities and rapid transmission resulting in high rates of infection [17]. In early 2021, we observed COVID-19 antibodies to spike to be present in greater than 50% of unvaccinated healthy blood donors [24].…”

Recipients of COVID-19 vaccines face challenges of SARS-CoV-2 variants

“…Neutralization titer was decreased against the Beta variant, a greater degree was found with the Delta variant. RBD binding antibodies of the serum samples were also decreased against the VOCs [58]. It was also reported that the neutralizing activity against wild-type virus was 80% after two doses of inactivated BBIBP-CorV and only 10% serum samples showed successful neutralization against the Omicron variant.…”

Single-shot AAV-vectored vaccine against SARS-CoV-2 with fast and long-lasting immunity

“…Previous studies confirmed a two-dose schedule of 2 μg BBIBP-CorV on Days 0 and 21 was sufficient to provide superior protection in mice and nonhuman primates and induce high levels of seroconversion rates and neutralization antibody titers in human 40 , 50 . Moreover, BBIBP-CorV demonstrated its good protective effect against SARS-CoV-2 variants such as B.1.351 (Beta) and B.1.617.2 (Delta) 51 . Therefore, our results indicate the S663V-RBD may provide a superior protective effect against SARS-CoV-2 and its variants.…”