Large-Scale Tests of Covid-19 Vaccines to Start in July

It will take months to determine whether the experimental vaccines actually provide any benefits.

A volunteer gets a shot in the first-stage safety study clinical trial of a potential vaccine for Covid-19 in March at the Kaiser Permanente Washington Health Research Institute in Seattle. (AP Photo/Ted S. Warren, File)

(AP) — The first experimental Covid-19 vaccine in the United States is on track to begin a huge study in July to prove if it can fend off the coronavirus, while hard-hit Brazil is testing a different shot from China.

Where to do crucial, late-stage testing and how many volunteers are needed to roll up their sleeves are big worries for health officials.

Moderna Inc. said Thursday the vaccine it is developing with the National Institutes of Health will be tested in 30,000 people in the United States. Some will get the real shot and some a placebo, and scientists will compare which group winds up with the most infections.

With far fewer Covid-19 cases in China, Sinovac Biotech turned to Brazil, the epicenter of Latin America’s outbreak, for part of its final testing. The government of São Paulo said Thursday that Sinovac will ship enough of its experimental vaccine to test in 9,000 Brazilians starting in July.

If it works, “with this vaccine we will be able to immunize millions of Brazilians,” said São Paulo’s Gov. Joao Doria.

Worldwide, about a dozen potential Covid-19 vaccines are in early stages of testing. The NIH expects to help several additional shots move into those final, large-scale studies this summer, including one made by Oxford University that’s also being tested in a few thousand volunteers in Brazil.

There is no guarantee any of the experimental shots will pan out.

But if all goes well, “there will be potential to get answers” on which vaccines work by the end of the year, Dr. John Mascola, who directs NIH’s vaccine research center, told a meeting of the National Academy of Medicine on Wednesday.

Vaccines train the body to recognize a virus and fight back, and specialists say it’s vital to test shots made in different ways — to increase the odds that at least one will work.

 Sinovac’s vaccine is made by growing the coronavirus in a lab and then killing it. So-called “whole inactivated” vaccines are tried-and-true, used for decades to make shots against polio, flu and other diseases — giving the body a sneak peek at the germ itself — but growing the virus is difficult and requires lab precautions.

The vaccine made by the NIH and Moderna contains no actual virus. Those shots contain the genetic code for the “spike” protein that coats the surface of the coronavirus. The body’s cells use that code to make some harmless spike protein that the immune system reacts to, ready if it later encounters the real thing. The so-called mRNA vaccine is easier to make, but it’s a new and unproven technology.

Neither company has published results of how their shots fared in smaller, earlier-stage studies, designed to check for serious side effects and how well people’s immune systems respond to different doses.

Even before proof that any potential vaccine will work, companies and governments are beginning to stockpile millions of doses so they can be ready to start vaccinating as soon as answers arrive.

In the United States, a program called “Operation Warp Speed” aims to have 300 million doses on hand by January. Under Brazil’s agreement with Sinovac, the Instituto Butantan will learn to produce the Chinese shot.


LAURAN NEERGAARD

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