COVID-19 vaccines - are we there yet?

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused the COVID-19 pandemic, a novel infectious disease with no prior population immunity.
• The virus continues to cause significant illness, necessitating the development of broadly effective vaccines.

Purpose of the Study:

• To review the status of COVID-19 vaccine development as of mid-December 2020.
• To identify key uncertainties regarding vaccine efficacy, duration, and impact on transmission.

Main Methods:

• Review of global COVID-19 vaccine development landscape.
• Analysis of vaccine candidates in Phase III clinical trials.
• Examination of available interim efficacy and safety data for leading vaccine types.

Main Results:

• Over 200 COVID-19 vaccine candidates were in development, with 11 in Phase III trials.
• Three vaccine types (protein-based, adenovirus vector, mRNA) were considered for Australian procurement.
• mRNA and adenovirus vector vaccines showed published interim efficacy results, with mRNA vaccine rollout initiated in several countries.

Conclusions:

• Significant uncertainties persist regarding vaccine effectiveness in high-risk populations (e.g., elderly, immunocompromised) and the duration of protection.
• The extent to which vaccines prevent infection, rather than just severe disease, is critical for achieving indirect (herd) protection through widespread vaccination.