A breakdown of the 4 COVID-19 vaccine trials in late-stage testing

Moncef Slaoui, PhD, chief of the White House task force to develop a safe and effective COVID-19 vaccine, has been reporting positive updates on the vaccine race, saying on Oct. 21 that all Americans should be inoculated by June. Four drugmakers have entered late-stage testing in the U.S. for experimental COVID-19 vaccine candidates, and the candidates vary significantly in terms of technology being used, conditions for storage and size of clinical trial.

Below is a breakdown of each candidate's trial progress.

AstraZeneca and University of Oxford's candidate:

AstraZeneca on Aug. 31 began enrolling up to 30,000 people in a phase 3 trial for the experimental COVID-19 vaccine it is developing with the University of Oxford. The trial, funded by the Biomedical Advanced Development Authority and the National Institutes of Health, will test the vaccine's safety, efficacy and immunogenicity. 

The vaccine candidate uses a chimpanzee viral vector based on a weakened version of an adenovirus. Trial participants receive two doses of the vaccine four weeks apart.

On Sept. 9, AstraZeneca voluntarily paused its phase 3 COVID-19 vaccine trial after a previously healthy 37-year-old trial participant experienced an adverse reaction. She was diagnosed with transverse myelitis, according to an internal safety report obtained by CNN

The drugmaker resumed the trial in the U.K. Sept. 12 after gaining approval from the Medicines Health Regulatory Authority, the country's equivalent of the FDA, but has yet to resume the trial in the U.S. In October, the FDA announced it had widened its investigation of the vaccine, further delaying the U.S. trial.

AstraZeneca published its COVID-19 vaccine clinical trial protocol Sept. 19. The 111-page protocol states that AstraZeneca's goal is to develop a vaccine with 50 percent effectiveness, which is what the FDA has set as its threshold for approval. 

Despite the trial's hold in the U.S., AstraZeneca CEO Pascal Soriot said he still expects the company to know by the end of the year whether its experimental COVID-19 vaccine is safe and effective.

Moderna's candidate:

Moderna began the phase 3 trial for its COVID-19 vaccine candidate July 26. The vaccine uses mRNA, meaning it seeks to mimic infection in the body by carrying the genetic instructions for cells to produce antigens that fight COVID-19. It is being developed in partnership with the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

The drugmaker plans to include 89 sites and about 30,000 people in its phase 3 trial. The results of the trial will determine whether two doses of its vaccine can protect against symptomatic COVID-19.

Moderna inked an agreement, which is valued at up to $1.53 billion, with the U.S. government  Aug. 11 for 100 million doses of its candidate. The U.S. has the option to purchase 400 million more doses.

During an Aug. 5 second quarter earnings call, CEO Stéphane Bancel said Moderna plans to charge $32 to $37 per dose for customers buying small orders of its COVID-19 vaccine. He said he considered small orders "more kind of in the millions," and countries seeking larger orders will be charged less per dose. Mr. Bancel also said Moderna will reassess the pricing of its COVID-19 vaccine after the World Health Organization declares the pandemic over, saying the drugmaker will wait to determine "the most optimal price." 

On Sept. 17, Moderna became the first drugmaker to release its vaccine trial protocol. It released a 135-page document that details how it is conducting its phase 3 trial and how safety and efficacy will be determined. 

The drugmaker said on Oct. 8 it will not enforce the patents it gained for its experimental COVID-19 vaccine and will license its COVID-19 vaccine intellectual property to other drugmakers after the pandemic is declared over.

Mr. Bancel said Oct. 19 that the company expects interim results from the trial in November, and the FDA could grant emergency use authorization in December if those results are positive. He also said Moderna will not seek FDA approval to use the vaccine in the general population until at least late January.

Pfizer and BioNTech's candidate:

Pfizer's phase 2/3 trial for the two-dose experimental COVID-19 vaccine Pfizer is developing with BioNTech commenced July 27. The candidate uses mRNA technology, similarly to Moderna's candidate.

On Sept. 12, Pfizer said it plans to expand its phase 3 vaccine trial from 30,000 people to 44,000. Five days later, it released its vaccine protocol.

Pfizer said it expects trial results as early as October and if successful, plans to supply up to 100 million doses by the end of 2020 and 1.3 billion by the end of 2021. 

The U.S. agreed to pay $1.95 billion July 22 for up to 600 million doses of the vaccine candidate. Pfizer is charging the U.S. $19.50 per dose for the first 100 million doses.

In October, Pfizer received FDA approval to test the vaccine candidate in children as young as 12. Its COVID-19 vaccine trial became the first in the U.S. to enroll children.

Uncertainties surround the distribution of Pfizer and BionNTech's vaccine candidates, as it must be stored at -94 degrees and its ordering system stipulates 975 doses as the lowest possible order.

To keep vaccines safe during distribution, Pfizer designed a reusable, suitcase-sized container to keep the vaccines at ultracold temperatures for up to 10 days. The containers, which are packed with dry ice and tracked by GPS, can hold 1,000 to 5,000 vaccine doses each. The drugmaker also repurposed its distribution centers in Pleasant Prairie, Wis., and Karlsruhe, Germany, to allow for extra storage capacity.

Johnson & Johnson's candidate:

Johnson & Johnson launched the phase 3 trial for its experimental COVID-19 vaccine Sept. 23, testing the single-shot candidate's effectiveness in preventing COVID-19 against a placebo. The drugmaker released its 163-page trial protocol when it announced phase 3 launch.

The vaccine candidate uses an adenovirus, which creates coronavirus proteins within the body that could prepare the immune system to fend off COVID-19. Adenovirus vaccines do not need to be stored in frozen settings, unlike most of the other vaccines in testing phases across the U.S.

The drugmaker aims to gather 60,000 trial participants in the U.S., Mexico, Argentina, Brazil, Chile, Colombia, Peru and South Africa. However, it voluntarily paused the clinical trial Oct. 12 after learning of a participant's unexplained illness. The study's online enrollment system has been closed, and its data and safety monitoring board has been convened to assess the situation, according to a document, obtained by STAT, that was sent to outside researchers running the trial. 

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