COVID-19 vaccines: their effectiveness against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its emerging variants

Abstract

Background The world has been suffering from the COVID-19 pandemic (officially declared by WHO in March 2020), caused by the severe acute respiratory β-coronavirus 2 (SARS-CoV-2) since the last week of December 2019. The disease was initially designated as a Public Health Emergency of International Concern on January 30, 2020. In order to protect the health of mass public, an array of research on drugs and vaccines against SARS-CoV-2 has been conducted globally. However, the emerging variants of SARS-CoV-2, i.e., Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) variants which evolved in late 2020 and the Omicron variant (B.1.1.529) which emerged in November 2021 along with its subvariant BA.2 which was first identified in India and South Africa in late December 2021, have raised the doubt about the efficiency of the currently used vaccines especially in terms of the consistent potential to produce neutralizing antibodies targeting the viral spike (S) protein. Main body of the abstract The present review discussed the functional details of major vaccines regarding their efficiency against such variants during the pandemic. Overall, the mRNA vaccines have shown around 94% effectiveness; the adenovector vaccine showed approximately 70% efficacy, whereas Sputnik V vaccines showed around 92% effectiveness; the inactivated whole-virus vaccine CoronaVac/PiCoVacc and BBIBP-CorV showed a varying effectiveness of 65–86% according to the geographic locations; the subunit vaccine NVX-CoV2373 has shown 60–89% effectiveness along with the global regions against the wild-type SARS-CoV-2 strain. However, reduced effectiveness of these vaccines against the SARS-CoV-2 variants was noticed which is suggestive for the further administration of booster dose. Short conclusion Maximum variants of SARS-CoV-2 emerged during the second wave of COVID-19; and extensive studies on the viral genomic sequences from all geographical locations around the world have been conducted by an array of groups to assess the possible occurrence of mutations(s) specially within the receptor binding domain of the viral spike (S) protein. Mutational similarities and the new or critical mutations within all variants have been clearly identified so far. The study of effectiveness of the currently used vaccines is also ongoing. The persistence of memory B cell action and the other immune components as well as the administration of booster dose is expected to mitigate the disease.

SARS-CoV-2 variants and the global pandemic challenged by vaccine uptake during the emergence of the Delta variant: A national survey seeking vaccine hesitancy causes

“…P681R being at the S1–S2 cleavage site may have increased the viral replication, which could lead to higher viral loads and transmission. As information of COVID-19 vaccines effectiveness against this variant translated on clinical outcomes is still evolving [10] , [11] , the most updated evidence is suggestive of variable response of this variant to the available vaccines with efficacy ranging from 60% for Johnson and Johnson vaccine and up to 94% for the Moderna, vaccine and the variation in efficacy was dependent on the time since vaccination and disease severity [12] , [13] .The aim of this study was to assess the level of COVID-19 vaccines hesitancy in KSA following the emergence and prevalence of the Delta variant.…”

Homologous and heterologous boosting of the ChAdOx1-S1-S COVID-19 vaccine with the SCB-2019 vaccine candidate: a randomized, observer-blinded, controlled, phase 2 study

“…Middle-and low-income countries are now playing catch-up, typically using less expensive and more easily managed inactivated vaccines. However, the steady emergence of a series of novel variants, the majority of which have changes in the main antigenic target, the S-protein, has seen a decline in the extent of protective immunity afforded by the initial vaccines [3][4][5][6][7][8]. The combination of waning antibodies and lower immunity against the novel variant has caused resurgence of COVID-19 outbreaks around the world, which may be countered by use of booster vaccinations [16].…”

Overview of dreadful consequences of SARS-CoV-2 invasion in Italy from March 2020 to March 2022

“…First, it was issued to the individuals who completed two basic courses of vaccines; lately, a super Green Pass has been issued for fully vaccinated persons with a full course (booster dose) of an approved vaccine (Ministero degli Affari Esteri 2022 ). From 23 September 2021, the Italian Ministry of Health approved vaccines which are recognised by WHO and equivalent officialdoms to prevent SARS-CoV-2, namely vaccines recognised by EMA—European Medicines such as Pfizer-BioNtech Comirnaty, Moderna, Vaxzevria, Janssen (Johnson & Johnson), Nuvaxovid (Novavax), Covishield, R-CoVI (R-Pharm), COVID-19 vaccine recombinant (Fiocruz) which are manufactured under licence from AstraZeneca (Kaushal & Noor 2022 ; Noor et al 2022 ; Ministero degli Affari Esteri 2022 ).…”