WASHINGTON – In a race for a vaccine designed to put an end to the global COVID-19 pandemic, eight participants pulled ahead.
Eight candidate vaccines are tested in humans in clinics in China, the United States, Britain and Germany. In addition to them, at least 94 are at different stages of development.
The Trump administration wants to have millions of doses available by the end of the year, but experts warn that unprecedented speed may be achieved by circumventing security measures and there is no guarantee that any of the candidate vaccines will be effective.
“I’m worried that we won’t find answers to key questions about safety and efficacy if we plan to get the vaccine so fast,” says Paul Offit, director of the Vaccine Education Center at the Children’s Hospital in Philadelphia.
Eight candidate vaccines fall into three categories.
The first category can be called the classical method: injection of a killed version of the virus to mobilize the patient’s immune system. Three independent groups of Chinese researchers are testing inactivated vaccines.
The second method uses one virus to fight another.
No matter what disease it causes — COVID-19, Ebola, or the common cold — the virus itself is just a shell that contains instructions for creating new copies of the virus.
In this new vaccine development strategy, scientists remove instructions from a single virus and replace them with instructions to create only part of the coronavirus.
The introduction of a modified virus does not cause disease. The virus infects some cells of the patient, but instead of copies of a dangerous virus, these cells produce only that part of the coronavirus. The patient’s immune system responds to the coronavirus protein and can cope with the intruder later.
This approach is used by two groups of scientists from China and the UK.
The third strategy excludes the intermediary. Instead of delivering instructions via the virus, the researchers enter the genetic code of the coronavirus element directly to the patient in the form of DNA or RNA.
Two groups are working on RNA vaccines; another is trying to develop a DNA vaccine.
Newer methods are faster and more flexible, says Kimberly Taylor, head of the biological defense vaccine development department at the National Institute of Allergy and Infectious Diseases.
“They are very good for pandemic platforms because they are usually built on a plug and play basis. They can be produced very quickly and delivered quickly to clinics, ”she explains.
Each technology has its pros and cons.
“We will not put all our eggs in one basket,” says Walter Orenstein, deputy director of Emory University Vaccine Center. “Different groups are watching what will work and what may not be.”