The conundrum of current anti-SARS-CoV-2 vaccines

Adverse Events of COVID-19 Vaccination among the Saudi Population: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to synthesize the evidence on the adverse events (AEs) of coronavirus disease 2019 (COVID-19) vaccinations in Saudi Arabia. A computerized search in MEDLINE via PubMed and OVID, Scopus, CENTRAL, and Web of Science was conducted using relevant keywords. The NIH tools were used for the quality assessment. A total of 14 studies (16 reports) were included. The pooled analysis showed that the incidence of AEs post-COVID-19 vaccination was 40.4% (95% CI:6.4% to 87%). Compared to the AstraZeneca vaccine, the Pfizer-BioNTech vaccine was associated with a lower risk ratio (RR) of wheezing (RR = 0.04), fever (RR = 0.32), chills (RR = 0.41), headache (RR = 0.47), dizziness (RR = 0.49), and joint pain (RR = 0.51). The Pfizer-BioNTech vaccine was associated with significantly higher RR of general allergic reactions (RR = 1.62), dyspnea (RR = 1.68), upper respiratory tract symptoms (RR = 1.71), and lymphadenopathy (RR = 8.32). The current evidence suggests that the incidence of AEs following COVID-19 vaccines is 40%; however, most of these AEs were mild and for a short time. The overall number of participants with AEs was higher in the Pfizer group compared to the AstraZeneca group; however, the AstraZeneca vaccine was associated with a higher RR of several AEs.

COVID-19 Vaccine: Between Myth and Truth

Since December 2019, a pandemic caused by the newly identified SARS-CoV-2 spread across the entire globe, causing 364,191,494 confirmed cases of COVID-19 to date. SARS-CoV-2 is a betacoronavirus, a positive-sense, single-stranded RNA virus with four structural proteins: spike (S), envelope (E), membrane (M), and nucleocapsid (N). The S protein plays a crucial role both in cell binding and in the induction of a strong immune response during COVID-19 infection. The clinical impact of SARS-CoV-2 and its spread led to the urgent need for vaccine development to prevent viral transmission and to reduce the morbidity and mortality associated with the disease. Multiple platforms have been involved in the rapid development of vaccine candidates, with the S protein representing a major target because it can stimulate the immune system, yielding neutralizing antibodies (NAbs), blocking viral entry into host cells, and evoking T-cell immune responses. To date, 178 SARS-CoV-2 vaccine candidates have been challenged in clinical trials, of which 33 were approved by various national regulatory agencies. In this review, we discuss the FDA- and/or EMA-authorized vaccines that are mostly based on mRNA or viral vector platforms. Furthermore, we debunk false myths about the COVID-19 vaccine as well as discuss the impact of viral variants and the possible future developments.

Adverse drug reactions from two COVID-19 vaccines reported in Saudi Arabia

Background

Several reports have been published about the impact of coronavirus disease 2019 (COVID-19) vaccines on human health, and each vaccine has a different safety and efficacy profile. The aim of this study was to reveal the nature and classification of reported adverse drug reactions (ADRs) of the two COVID-19 vaccines (tozinameran and ChAdOx1) among citizens and residents living in Saudi Arabia, and show possible differences between the two vaccines and the differences between each batch on the health of populations.

Methods

A cross-sectional study was conducted in Saudi Arabia between December 2020 and March 2021. Saudi citizens and residents aged ≥ 16 years who had at least one dose of any batch of either of the two approved COVID-19 vaccines (tozinameran and ChAdOx1) and who reported at least one ADR from the vaccines were included. The study excluded people who reported ADRs after receiving tozinameran or ChAdOx1 vaccines but no information was provided about the vaccine’s batch number.

Results

During the study period, 12,868 vaccinated people, including a high-risk group (i.e., those with chronic illness or pregnant women), reported COVID-19 vaccine ADRs that had been documented in the General Directorate of Medical Consultations, Saudi Ministry of Health. The study reported several ADRs associated with COVID-19 vaccines, with the most common (> 25%) being fever/chills, general pain/weakness, headache, and injection site reactions. Among healthy and high-risk people, the median onset of all reported ADRs for tozinameran and ChAdOx1 vaccine batches were 1.96 and 1.64 days, respectively (p < 0.01). Furthermore, significant differences (p < 0.05) were recorded between the two studied vaccines in regard to fever/chills, gastrointestinal symptoms, headache, general pain/weakness, and neurological symptoms, with higher incidence rates of these ADRs observed with the ChAdOx1 vaccine than the tozinameran vaccine. However, the tozinameran vaccine was found to cause significantly (p < 0.05) more palpitation, blood pressure variations, upper respiratory tract symptoms, lymph node swelling, and other unspecified ADRs than the ChAdOx1 vaccine. Among patients vaccinated with seven different batches of the tozinameran vaccine, people vaccinated with the T4 and T5 batches reported the most ADRs.

Conclusion

There were significant differences regarding most of the reported ADRs and their onset among tozinameran and ChAdOx1 vaccines on both healthy people and high-risk individuals living in Saudi Arabia. Moreover, the study found that the frequencies of most listed ADRs were statistically different when seven batches of tozinameran vaccine were compared.

Evaluation of Three Quantitative Anti-SARS-CoV-2 Antibody Immunoassays

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 and caused a dramatic pandemic. Serological assays are used to check for immunization and assess herd immunity. We evaluated commercially available assays designed to quantify antibodies directed to the SARS-CoV-2 Spike (S) antigen, either total (Wantaï SARS-CoV-2 Ab ELISA) or IgG (SARS-CoV-2 IgG II Quant on Alinity, Abbott, and Liaison SARS-CoV-2 TrimericS IgG, Diasorin). The specificities of the Wantaï, Alinity, and Liaison assays were evaluated using 100 prepandemic sera and were 98, 99, and 97%, respectively. The sensitivities of all three were around 100% when tested on 35 samples taken 15 to 35 days postinfection. They were less sensitive for 150 sera from late infections (>180 days). Using the first WHO international standard (NIBSC), we showed that the Wantai results were concordant with the NIBSC values, while Liaison and Alinity showed a proportional bias of 1.3 and 7, respectively. The results of the 3 immunoassays were significantly globally pairwise correlated and for late infection sera (P < 0.001). They were correlated for recent infection sera measured with Alinity and Liaison (P < 0.001). However, the Wantai results of recent infections were not correlated with those from Alinity or Liaison. All the immunoassay results were significantly correlated with the neutralizing antibody titers obtained using a live virus neutralization assay with the B1.160 SARS-CoV-2 strain. These assays will be useful once the protective anti-SARS-CoV-2 antibody titer has been determined.

IMPORTANCE Standardization and correlation with virus neutralization assays are critical points to compare the performance of serological assays designed to quantify anti-SARS-CoV-2 antibodies in order to identify their optimal use. We have evaluated three serological immunoassays based on the virus spike antigen that detect anti-SARS-CoV-2 antibodies: a microplate assay and two chemiluminescent assays performed with Alinity (Abbott) and Liaison (Diasorin) analysers. We used an in-house live virus neutralization assay and the first WHO international standard to assess the comparison. This study could be useful to determine guidelines on the use of serological results to manage vaccination and treatment with convalescent plasma or monoclonal antibodies.

Initial SARS-CoV-2 vaccination response can predict booster response for BNT162b2 but not for AZD1222

Objective: To determine whether severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibody levels after the first dose of vaccine can predict the final antibody response, and whether this is dependent on the vaccine type.

Methods: Sixty-nine recipients of BNT162b2 (Pfizer/BioNTech) and 55 recipients of AZD1222 (AstraZeneca), without previous infection or immunosuppressive medication, were included in this study. Antibody levels were quantified 3 weeks after the first dose [directly before boostering in the case of AZD1222 (11 weeks after the first dose)] and 3 weeks after the second dose using the Roche Elecsys SARS-CoV-2 S total antibody assay.

Results: Median pre-booster {BNT162b2: 80.6 [interquartile range (IQR) 25.5–167.0] binding antibody units (BAU)/mL; AZD1222: 56.4 (IQR 36.4–104.8) BAU/mL; not significant} and post-booster [BNT162b2: 2092.0 (IQR 1216.3–4431.8) BAU/mL; AZD1222: 957.0 (IQR 684.5–1684.8) BAU/mL; P<0.0001] levels correlated well in the recipients of BNT162b2 (ρ=0.53) but not in the recipients of AZD1222. Moreover, antibody levels after the first dose of BNT162b2 correlated inversely with age (ρ=-0.33, P=0.013), whereas a positive correlation with age was observed after the second dose in recipients of AZD1222 (ρ=0.26, P=0.030).

Conclusions: The results of this study suggest that antibody levels quantified by the Roche Elecsys SARS-CoV-2 S assay before the booster shot could infer post-booster responses to BNT162b2, but not to AZ1222. In addition, this study found a vaccine-dependent effect on antibody responses, where age seems to play an ambivalent role.