Vaccination for COVID-19: Is it important and what should you know about it?

Chao-Ping Wu; Fatima Adhi; Daniel Culver

doi:10.3949/ccjm.88a.ccc076

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TABLE 1

Available vaccine platforms

	Pros	Cons	Approved vaccines in use
Whole inactivated (killed) virus	Easily manufactured Strong immune response Mature technique	Possible Th2 bias Requires large quantities of virus Risk of vaccine-enhanced disease Requires booster shots	Influenza, rabies, hepatitis A, injectable polio

Live attenuated virus	Entire viral repertoire Very strong cytotoxic response Mature technique	Risk of reversion/recombination Risk of infection in immunocompromised patients Requires cold chain distribution	Measles, rubella, mumps, yellow fever

Protein subunits	Simple to produce Safe, few side effects	Less immunogenic Requires adjuvants Slower manufacture	Influenza A strains, hepatitis B, acellular pertussis

Viral-like protein	Safe and stable Immunogenicity	Enveloped VLP more challenging to produce	HPV, preclinical SARS-CoV-1

DNA	Rapid development Noninfectious Thermostable	Potential integration to host genome Less Immunogenicity Delivery challenging; requires cold chain distribution	Not currently licensed

mRNA	Rapid development Noninfectious, non-integrating	Instability Low immunogenicity Delivery challenging; requires cold chain distribution	SARS-CoV-2: EUA from FDA (Pfizer, Moderna)

Viral vectors	Safe Durable response	Pre-existing immunity against vector	Ebola. SARS-CoV-2: EUA from FDA (Johnson & Johnson)

EUA = emergency use authorization; FDA = Food and Drug Administration; HPV = human papilloma virus; mRNA = messenger ribonucleic acid; SARS-CoV = severe acute respiratory syndrome; Th2 = T helper type-2 cells; VLP = viral-like protein

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TABLE 2

Vaccine candidates in phase 3 or higher clinical trials

Developer (Vaccine name)	Platform	Vaccine type	Doses	Efficacy	Regulatory status	Clinical stage
United States
BioNTech-Pfizer (BNT162b2)	RNA	Messenger RNA expressing spike protein	2 (0, 21 days)	95%	EUA in the US, EU, other countries. WHO EUL	3

Moderna-NIAID (mRNA-1273)	RNA	LNP encapsulated mNRA	2 (0, 28 days)	94.1%	EUA in the US, EU, UK, other countries	3

University of Oxford AstraZeneca (AZD1222)	Viral vector	ChAdOxnCoV-19 (non-replicating adenovirus)	1-2 (0, 28 days)	66.7%	Emergency use in UK, EU, other countries. WHO EUL	3

Johnson & Johnson-Janssen (JNJ-78436735)	Viral vector	Ad26COVS1 (non-replicating adenovirus)	1-2 (0, 56 days)	57%–72%	EUA in the US	3

Novavax (NVX-CoV2373)	Protein subunit	Spike protein plus Matrix-M	2 (0, 21 days)	49.4%–89.3%	EUA submission planned for early 2021	3

Sanofi-GSK	Protein subunit	Spike protein (baculovirus production)	2 (0, 21 days)	Not available	Started a phase 2 trial in February 2021	1/2
Other countries
CanSino China (Convidecia) China	Viral vector	Ad5 nCoV (non-replicating AdV5 expressing spike protein)	1	Not available	Limited use in China	3

Sinopharm-Beijing (BBIBP-CorV) China	Inactivated	Inactivated virus	2 (0, 21 days)	79.3%–85%	Approved in China, UAE, Bahrain; emergency use in Egypt, other countries	3

Sinopharm-Wuhan China	Inactivated	Inactivated virus	2 (0, 21 days)	Not available	Limited use in China, UAE	3

Sinovac (CoronaVac) China	Inactivated	Inactivated virus plus aluminum hydroxide	2 (0, 14 days)	50.4%–91.3%	Approved in China; emergency use in Brazil, other countries	3

Gamaleya (Sputinik V) Russia	Viral vector	Adenovirus 26/5	2 (0, 21 days)	91.6%	Early use in Russia; emergency use in other countries	3

Bharat Biotech (Covaxin) India	Inactivated	Whole-virion inactivated SARS-CoV-2 vaccine	2 (0, 14 days)	Not available	Emergency use in India	3

EU = European Union; EUA = emergency use authorization; EUL = emergency use listing; GSK = GlaxoSmithKline; LPN = lipid nanoparticle-based; NIAID = National Institute for Allergy and Infectious Disease; UAE = United Arab Emirates; UK = United Kingdom; WHO = World Health Organization
Adapted from references 5,8