An Update on the Status of Vaccine Development for SARS-CoV-2 Including Variants. Practical Considerations for COVID-19 Special Populations

Abstract

The progress in the development of various vaccine platforms against SARS-CoV-2 have been rather remarkable owing to advancement in molecular and biologic sciences. Most of the current vaccines and those in development focus on targeting the viral spike proteins by generating antibodies of varying spectrum. These vaccines represent a variety of platforms including whole virus vaccines, viral vector vaccines, nucleic acid vaccines representing RNA, DNA, and their hybrid forms. The therapeutic efficacy of these vaccines varies owing to their pharmacodynamic individualities. COVID-19 variants are capable of inducing different pathologic responses and some of which may be resistant to antibodies generated by current vaccines. The current clinical use of these vaccines has been through emergency use authorization until recently. Moreover, the efficacy and safety of these vaccines have been tested in substantial numbers of individuals but studies in special populations that better reflect the global population are pending results. These specialized populations include young children, immunocompromised patients, pregnant individuals, and other specialized groups. Combination approaches, molecularly modified vaccination approaches, and vaccines conferring longer periods of immunity are being currently being investigated, as well as pharmacovigilance studies. The continual transformation of SARS-CoV-2 and its variants are of concern along with the breakthrough infections. These considerations pose new challenges for the development of vaccination platforms. For this purpose, booster doses, combination vaccine approaches, and other modalities are being discussed. This review provides an updated account of currently available vaccines and those in advanced development with reference to their composition and mechanisms of action. A discussion on the use of vaccines in special populations including immunocompromised patients, pregnant women and other specialized populations are also included.

Development of DNA Vaccine Candidate against SARS-CoV-2

“…As to the non-mRNA-based vaccines, AstraZeneca has announced 70%, while Sinopharm elicited 79% efficacy [ 31 ]. Besides, there are a huge number of the whole virion-, viral vector-, nucleic acid-, and recombinant protein-based COVID-19 vaccines in phase 1–4 clinical trials [ 32 ]. Nevertheless, despite the presence and availability of vaccines against SARS-CoV-2 [ 9 , 33 ], the need for more, highly effective and safe vaccines remains still emergent to finally combat this infectious disease.…”

COVID-19 in Pregnancy: Knowledge about the Vaccine and the Effect of the Virus. Reliability and Results of the MAMA-19 Questionnaire

“…Thirdly, in light of the new evidence on COVID-19 vaccination effects, the introduction of new vaccines and COVID-19’s continued viral evolution, some questions should be further modified or deleted [ 39 ].…”

COVID-19 2022 update: transition of the pandemic to the endemic phase

“…Despite a widespread mistrust about safety and speed of production, nowadays, we can benefit of two types of vaccines against SARS-CoV-2 and of a growing number of data that support their efficacy and safety. Two messenger RNA (mRNA) (BNT162b2 and mRNA-1273) and two viral vector (ChAdOx1 nCoV-19 AZD1222 and Ad26.COV2.S) COVID-19 vaccines were developed [ 117 ]. A third type, protein subunit vaccines (NVX-CoV2373), has been approved by EMA, Indonesia, Australia and South Korea, while is still lacking a full approval by the FDA.…”