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COVID-19 vaccine volunteers are still needed, scientists say

Two COVID-19 vaccines could be nearing the goal, but scientists warn that it’s paramount that enough people volunteer to help finish studying other vaccine candidates in the United States and around the world.

Moderna Inc. and its competitor Pfizer Inc. recently announced preliminary results showing that their products appear to be 95% and 90% effective against COVID-19, at least for short-term protection.

If those early results hold up – and US regulators agree the vaccines are safe – emergency use of small, rationed supplies could begin in late December. Other countries with contracts for early doses would conduct their own studies.

But multiple vaccines will be needed to meet global demand and help end the pandemic. And that raises concern that the clinical trials that still need to enroll thousands of volunteers will be insufficient, if people decide to wait for an option that is already fully approved and safe.

“We don’t want that to happen,” said Dr. James Cutrell, an infectious disease expert at UT Southwestern Medical Center in Dallas.

Supplies aside, other COVID-19 vaccines in development may work differently in various populations, Cutrell explained, and “we probably benefit from having a menu of different vaccine options.”

“We still need volunteers,” emphasized Dr. Francis Collins, director of the National Institutes of Health (INS). He asked Americans to enroll in clinical trials.

Also, participants in the Moderna and Pfizer studies who originally received sham injections will almost certainly be offered the actual vaccine, if the US Food and Drug Administration allows its emergency use. But no one knows how long the protection will last, which means those studies must also continue to track recipients in some way.

“It’s one thing to be effective two months after the last vaccination, it’s another to be effective one year later,” said Dr. Jesse Goodman of Georgetown University, former director of the Food and Drug Administration’s vaccine division. Medicines. “It’s going to be very important to complete these clinical trials and those of the other vaccines so that we can compare them.”

The promising news from Moderna and Pfizer bodes well for some of their competitors, said Dr. Anthony Fauci, the US government’s leading infectious disease expert, whose team at INS helped develop Moderna’s candidate.

Those injections target the “spike” protein that sticks to the surface of the coronavirus, and early results show that it is enough to generate a “protective response,” Fauci said. “Conceptually, this looks good” for other similar vaccines made in different ways.

Below is a table of the pioneers in the global vaccine race:

Genetic code vaccines

The Moderna-INS vaccine, and the candidate developed by Pfizer and its German partner BioNTech, are not made with the coronavirus itself, so there is no chance that someone could get it from injections.

Instead, the vaccines are made using a new technology that injects a piece of genetic code for the coronavirus spike protein. That messenger RNA, or mRNA, signals the body to produce a harmless spike protein, enough to prime the immune system to react if it later encounters the real virus.

Currently, there are no licensed mRNA vaccines for people, so scientists had no idea whether the candidates for protection against COVID-19 infection might work or their range of effectiveness.

Both manufacturers are working to increase production at factories in the United States and Europe. They can’t just partner with other vaccine companies to take on some of the work because the technology is so different from the way most injections are done today.

“It is not a very easy or fast exchange,” explained Moderna CEO Stéphane Bancel.

Trojan horse vaccines

These target the coronavirus spike protein in another way: They use a different, harmless virus to carry the spike gene into the body. Once again, the body produces a spike protein and prepares the immune system to recognize it.

The University of Oxford and Britain’s AstraZeneca are making their version of this “viral vector” vaccine using a cold virus, or adenovirus, that normally infects chimpanzees. Studies are being conducted with tens of thousands of people in the United Kingdom, the United States, and some other countries.

Johnson & Johnson is using a human adenovirus for its candidate vaccine. It is the only option in advanced testing in the United States that aims to show whether a single dose, rather than two, would suffice.

The government of China authorized the emergency use of CanSino Biologics adenovirus injections in the military prior to any final testing. Russia also began offering an adenovirus vaccine before late-stage testing.

Protein vaccines

Novavax produces its vaccine candidate by growing harmless copies of the coronavirus spike protein in the laboratory and packaging them into virus-sized nanoparticles.

Protein-based vaccines exist against other diseases, so the technology is not as novel as some of its competitors. Novavax has started a large end-stage study in Great Britain and will soon start another in the United States.

“Killed” virus vaccines

Peak-focused vaccines aren’t the only option. Making vaccines by growing a virus that causes disease and then killing it is a tried and true approach — it’s the way Jonas Salk’s famous polio vaccines were made.

China has three “inactivated” COVID-19 vaccine candidates in final testing in several countries, and has allowed emergency use in some people ahead of the results. An Indian company is testing its own inactive candidate.

Safely brewing and then removing the virus takes more time than newer technologies. But inactivated vaccines give the body a sneak peek at the coronavirus itself instead of just the single spike protein.

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