Thread by @LizSzabo

What's the scoop on coronavirus vaccines? Follow this thread and read our story to get the essentials. 1/

scientificamerican.com/article/fauci-… via @sciam

@khnews asked Dr. Anthony Fauci about reports that antibodies to covid-19 fade after a few months. If true, would that mean that vaccine protection would wear off after a few months? He said, “If we don’t get as long a response as we want, we can always give a booster shot.” 2/

Leading covid-19 vaccine candidates are based on new approaches that have never resulted in a licensed vaccine. Moderna, a relatively young company, has yet to produce any approved vaccines.

“Even more so than usual, as we create vaccines, we’re sailing in uncharted water.” 3/

Researchers can develop covid-19 vaccines quickly partly b/c of new technology, such as mRNA. At least three of the leading vaccine candidates are based on mRNA, or genetic material from virus. But this method has never led to a licensed vaccine. 4/

What is an mRNA vaccine? Unlike traditional vaccines, which expose the body to a viral protein to stimulate the immune system, mRNA acts as an instruction kit, telling body how to construct the proteins itself. The immune system then responds by making antibodies. 5/

How are covid-19 vaccines being made so fast?

Moderna was able to produce the COVID-19 vaccine so rapidly because they had developed experimental vaccines against two other lethal coronaviruses—those that cause SARS and MERS—which are closely related to the COVID-19 virus. 6/

Moderna’s vaccine was ready for a trial so quickly because “98% of the scientific work had been done” already Schaffner said. “They went back to these scientific methods and adapted them very quickly. That saves years of work.” 7/

Nearly all the covid-19 vaccines in development target the same protein (the "spike" protein). Some say that makes sense. Others say we should diversify our portfolio of vaccines, with some targeting other proteins, to hedge our bets. 8/

Does the covid-19 vaccine cause side effects? Although some volunteers developed fevers and headaches after vaccination, these side effects were no worse than those caused by other licensed vaccines, Fauci said.

“That’s not a showstopper at all,” he said. 9/

@DrPaulOffit Why is it tricky to make an effective vaccine against the coronavirus? “This virus does things that no other virus does.”10/

@drpauloffit: “It’s easier to create a vaccine for diseases that confer long-term immunity.” Measles provides good immunity & the vaccine is very strong. But you can catch strep throat over and over, so there's no vaccine against it. scientificamerican.com/article/fauci-… 11/

In a recent New England Journal of Medicine report on COVID-19 survivors, antibody levels dropped rapidly over three months, at a rate that could leave them without any antibodies within one year. “One wants a vaccine that lasts longer than two months,” Schaffner said. 12/

Conflicting evidence on covid-19 antibodies. A July paper found that COVID-19 infection “induces robust, neutralizing antibody responses that are stable for at least three months.” @florian_krammer: “What we found looks like a normal antibody response to a viral infection,”13/

Conflicting evidence on antibodies “shouldn’t interfere with efforts to develop a safe and effective vaccine,” added Fauci, noting he’s encouraged by the results of early clinical trials. “The durability of the vaccine may be quite good.” 14/
scientificamerican.com/article/fauci-…

@moderna_tx doc said he hopes vaccinated people will have a stronger immune response than those sickened by the coronavirus. He said it’s possible the virus not only infects cells, but also dampens the immune system, suppressing antibody response. 15/

There’s more to the immune system than antibodies.

The body is also protected by memory T-cells, which can recognize viral threats to stimulate the production of antibodies even after many years. Studies show covid-19 survivors have these T-cells. 16/

How well will a covid-19 vaccine work? We don't know. But it may be more like the flu shot, which doesn't prevent 100% of infections, but does help prevent hospitalization and death. So you may still get a mild case of covid-19, but hopefully not end up in the ICU. 17/

@AmeshAA & @PeterHotez told @Khnews that the first covid-19 vaccine may not be the most successful. Luckily, there are dozens in the pipeline. Maybe one will work better in old people, another may work better in kids. We may be able to tailor a vaccine to your risks. 18/

An ideal covid-19 would prevent all infections, said @drpauloffit. A less-effective shot would prevent severe disease/save lives, w/o preventing all infections. In this scenario, you'd get infected/still shed virus, spread the virus, even if you don't get sick. 19/

If covid-19 vaccine is less effective than we hope, it may not dramatically slow the spread of the pandemic, said @drpauloffit. In that case, you’d still need masks and social distancing. It’s going to take both—a vaccine and these hygienic measures—to defeat the virus.” 20/20