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Is the day at hand when COVID-19 will be a preventable disease? Is a vaccine possible? Is it achievable in the foreseeable future? We endeavor here to shed some light on these questions.

Vaccine Testing

New vaccines pass through several phases. Preclinical testing consists in inoculating animals with the vaccine to determine if it produces an immune response. Phase 1 Safety trials consist of using on a small number of people to determine safety and dosage and to confirm stimulation of immunity. Phase 2 Expandedtrials involve hundreds of people divided into different groups to determine if the vaccine acts differentially. Phase 3 Efficacy trials involve thousands of people to compare the vaccine to an inactive placebo. Approvalis granted by regulators based on the vaccine’s performance in these trials. However, Emergency Use Authorization may be granted before final approval in extenuating circumstances. [1]

To reduce delays, Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, has indicated that manufacturers will begin producing COVID-19 vaccine in anticipation of approval so that if a product gets the okay for usage, distribution can begin quickly. [2]

Number of Vaccines

Scientists worldwide are working on vaccine development. There may currently be more than 140 COVID-10 vaccines in progress, according to the World Health Organization. Here are some of the vaccine candidates farthest along in their development. [1]


This is a promising candidate being developed by Moderna. The Phase 1 trial involved 45 people divided into groups that received doses of 25, 100, and 250 micrograms. According to Moderna, all subjects developed antibodies, but the eight who received 25 or 100 micrograms developed more COVID-19 antibodies than people who actually recovered from the disease. The data has not been peer-reviewed or journal-published. As of this writing, this vaccine is in Phase 2 trials. [3]


The AZD1222 vaccine was developed by Oxford University’s Jenner Institute, for production by Astra Zeneca. It is based on a chimpanzee adenovirus. It would be administered in one dose and would not replicate. The vaccine is reported to have performed well in a Phase 1 trial with 320 people. It is currently in Phase 2/3 trials in England and Brazil. [4]


Ad5-nCoV vaccine is the product of a collaboration between a Chinese biologics company and Canada’s Precision NanoSystems. It utilizes a platform the Chinese company developed for its vaccine against Ebola. When the vaccine’s Phase 1 trial on 108 subjects was published in The Lancet, it became the first clinical study of a vaccine to be published in a peer-reviewed journal. Ad5-nCoV was found to be tolerable and immunogenic at 28 days post-vaccination and is now in Phase 2. [5]


NVX‑CoV2373 is a vaccine developed by Novavax using its proprietary nanoparticle technology carrying fragments of corona virus proteins along with its proprietary adjuvant Matrix-MTM, which stimulates higher levels of neutralizing antibodies. Phase 1 has enrolled 130 healthy subjects at two sites in Australia to assess doses of 5 and 25 micrograms, with and without Matrix-M. It is currently in Phase 1/2. [6]


CoronaVac is an inactivated virus vaccine created by the Chinese company Sinovac Biotech. Phase 1 testing has included 143 volunteers while Phase 2 has had 600 volunteers. The Phase 2 trial has shown neutralizing antibodies produced 14 days after vaccination and a seroconversion rate of 90%. Phase 3 clinical studies are projected in collaboration with Instituto Butantan in Brazil. [7]

Sinopharm Vaccine

The state-owned Chinese company Sinopharm has produced an inactivated virus vaccine initially tested in 96 subjects in a randomized, double-blind, placebo-controlled trial during which it reportedly evidenced a good safety profile. The current Phase 2 trial focuses on the vaccination procedure. [8]

These last two vaccines, CoronaVac and Sinopharm Vaccine, are based on an existing whole-virus technology. The advantage is that, as such, they are more familiar to produce. The disadvantage is that they may require multiple doses or act more slowly to produce immunity.

It is important that one or more of these vaccines succeed in order to produce individual as well as herd immunity to end the threat of COVID-19. Hopefully it will soon join polio, smallpox, and other diseases that have been eradicated.

Thomas Falasca, DO


[1] Coronavirus Vaccine Tracker, New York Times,

By Jonathan Corum and Carl Zimmer June 10, 2020

[2] Medscape Medical News

Fauci: US Poised to Produce a COVID-19 Vaccine

Gregory Twachtman

May 12, 2020

[3] Medscape, First COVID-19 Vaccine Tested on Humans Shows Early Promise,

Ralph Ellis May 18, 2020

[4] AstraZeneca advances response to global COVID-19 challenge as it receives first commitments for Oxford’s potential new vaccine, Adrian Kemp


[5] CanSino Publishes Phase I Data for COVID-19 Vaccine Candidate, Moves into Phase II

Published: May 22, 2020 By Alex Keown

[6] Novavax Initiates Phase 1/2 Clinical Trial of COVID-19 Vaccine, Novavax Press release, GAITHERSBURG, Md., May 25, 2020

[7] Sinovac Announces Positive Preliminary Results of Phase I/II Clinical Trials for Inactivated Vaccine Candidate Against COVID-19, June 13, 2020 01:45 PM Eastern Daylight Time

27 APRIL 2020 NEWS, China approves clinical trials of third Covid-19 vaccine candidate

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