The United Arab Emirates (UAE) government granted emergency use authorization for the Sinopharm vaccine (BBIBP-CorV) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection for frontline workers in September 2020^[1]. The BBIBP-CorV vaccine was then authorized for public use in December 2020. Today the BBIBP-CorV vaccine is the most widely administered vaccine in the UAE, where 97% of the adult population is fully vaccinated against SARS-CoV-2 infection^[2].

This vaccine was developed by China National Biotec Group (CNBG) Company Limited, Beijing, and is an inactivated vaccine based on whole-virion inactivated Vero cell technology^[3]. This technology differs from other vaccines approved for emergency use, such as those that are viral vectors (e.g., adenovirus, University of Oxford/AstraZeneca, Gamaleya Sputnik V, and Johnson & Johnson), and mRNA vaccines (Moderna and Pfizer-BioNTech)^[3].

In 2021, CNBG collaborated with the UAE to conduct the first phase III randomized clinical trial (RCT), led by Dr. Nawal Al kaabi^[4]. Phase III data revealed that two doses of the BBIBP-CorV vaccine, given at a three-week interval, were 78% effective in preventing symptomatic COVID-19 infections. Although RCTs are the gold standard for measuring the efficacy of new vaccines, it is important to explore vaccine efficacy in real-world data (RWD). This is because RCT data and RWD may differ due to the impact of age, gender, and comorbidities represented in the studied population. Further, the efficacy of a vaccine can be impacted by the specific SARS-CoV-2 strain present. As such, the date of participants’ study recruitment (which corresponds with the most prevalent SARS-CoV-2 strain at the time) is an important factor to consider.

To bridge the gap between data yielded from RCTs and the real-world, Dr Nawal Al kaabi and the team conducted a retrospective cohort study using electronic health records of 3,147,869 adults. The study was designed to investigate the effectiveness of the Sinopharm vaccine (BBIBP-CorV) in preventing severe outcomes of COVID-19 in Abu Dhabi (UAE). Severe outcomes included hospital admissions, admissions to critical care, and COVID-19 related deaths over a period of three months. In addition, the research team assessed the longer-term vaccine effectiveness over 12 months.

Study Findings: 3 Months Post-Vaccination

This study compared individuals who had previously taken two doses of BBIBP-CorV vaccine with unvaccinated individuals (known as ‘controls’). The two groups were equally balanced according to age, sex, ethnicity, comorbidities and the date of study entry. Three months after study initiation, vaccinated individuals had numerically less COVID-19 related hospitalisations, critical care admissions and deaths (Table 1.)

Table 1: Three months follow up data regarding COVID-19 related hospitalisations, critical care admissions and deaths.

COVID-19 Hospitalization: BBIBP-CorV was more effective against COVID-19 hospitalization in females (82.3%) compared to males (p<0.001), in individuals less than 60 years old (84.7%) compared to more than 60 years of age (p<0.001), and in individuals with comorbidities (83.5%) compared to individuals without comorbidities (p<0.001). 

Critical Care Admission: BBIBP-CorV was more effective against critical care admission in males (89.3%) compared to females (p<0.001), in individuals with comorbidities (88.7%) compared to those without comorbidities (p<0.001), and during the months of October to December 2020 (98.8%) compared with January to July 2021 (p<0.001).

Death: BBIBP-CorV effectiveness against death was modified by comorbidity and the month of study entry with the highest level observed for patients with comorbidity (97.1%, p<0.001) and during October through to December 2020 (99.9%, p<0.001).

Study Findings: 12 Months Post-Vaccination

BBIBP-CorV effectiveness was evaluated every month post-vaccination over 12 months (up to the 30th of September 2021).

COVID-19 Hospitalization: BBIBP-CorV protection against COVID-19 hospitalisation reduced by 20.7% from month two (82.8% effective) to month six (62.1% effective), after complete vaccination (i.e. 14 days after second dose). No further decline in effectiveness was observed after month seven until month twelve, post-vaccination.

Critical Care Admission: BBIBP-CorV protection against critical care admission was reduced by 12.9% from month two (85.7% effective) to month six (72.8% effective), after complete vaccination. No further decline in effectiveness was observed after month seven until month twelve, post-vaccination.

Death: BBIBP-CorV protection against COVID-19 death remained above 80% throughout the study and did not show a significant decline over the 12-month follow-up period.

Study Findings in Context

These findings reveal overall lower effectiveness than those reported from the phase III RCT, which demonstrated 100% efficacy against severe COVID-19 cases^[4]. Dr Nawal Al kaabi and her team attributed these differences to the use of RWD in the current study, as previously discussed. Further, the lower effectiveness of BBIBP-CorV vaccine revealed in the current study may reflect the emergence of novel variants of the SARS-CoV-2 virus, which have been shown to escape vaccine protection^[5]. Interestingly, the effectiveness of BBIBP-CorV vaccine against critical care admissions and death was also lower than reported in a previous retrospective BBIBP-CorV vaccine study conducted in Abu Dhabi (UAE)^[6]. It is possible that the use of a smaller sample size, shorter follow-up duration, and sole inclusion of patients with severe cases of COVID-19 may have previously over-estimated the vaccine effectiveness.

Dr Nawal Al kaabi’s Key Take-Aways

1. The inactivated BBIBP-CorV (Sinopharm) vaccine was effective in preventing and reducing COVID-19 related hospitalizations, critical care admissions, and mortality.
2. Gender, age, and comorbidities impact vaccine effectiveness.
3. Booster doses are important to increase protection against severe COVID-19 outcomes.
4. Continued monitoring of vaccine effectiveness over time is pivotal to inform policy.

References

1. Al Kaabi, N., et al., The incidence of COVID-19 infection following emergency use authorization of BBIBP-CORV inactivated vaccine in frontline workers in the United Arab Emirates. Scientific reports, 2022. 12(1): p. 1-8.
2. (NCEMA)., N.C.E.M.A. [cited 2022 6 April]; Available from: https://covid19.ncema.gov.ae/en/page/about-the-vaccine.
3. Pavel, S.T.I., et al., Development of an Inactivated Vaccine against SARS CoV-2. Vaccines, 2021. 9(11): p. 1266.
4. Al Kaabi, N., et al., Effect of 2 inactivated SARS-CoV-2 vaccines on symptomatic COVID-19 infection in adults: a randomized clinical trial. Jama, 2021. 326(1): p. 35-45.
5. Pouwels, K.B., et al., Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. Nature medicine, 2021. 27(12): p. 2127-2135.
6. AlHosani, F.I., et al., Impact of the Sinopharm’s BBIBP-CorV vaccine in preventing hospital admissions and death in infected vaccinees: Results from a retrospective study in the emirate of Abu Dhabi, United Arab Emirates (UAE). Vaccine, 2022. 40(13): p. 2003-2010.