Dan Barouch, MD, PhD (Center for Virology and Vaccine Research, BIDMC) and colleagues reported in Science two studies of laboratory monkeys that suggest antibodies produced during recovery from COVID-19 provide immunity from the virus, whether triggered by infection or vaccine.

USA Today – May 22, 2020

Latest on global search for coronavirus vaccine: Three candidates show early promise

An all-out global race to develop a safe vaccine against coronavirus is underway. The stakes couldn’t be higher: an effective vaccine or treatment against the virus that causes COVID-19 is necessary to fully restart economies and resume civic life.

As the pace accelerates, USA TODAY is rounding up some of the week’s most notable vaccine developments.

They include a massive contract by the U.S. government to get dibs on a possible vaccine that may or may not work, very early but promising news on two different vaccine candidates, one from China and one from the United States, and a caution that sometimes biology can’t be sped up as much as we might want.

A vaccine could work, which we didn’t know before

Given all the discussion of a coronavirus vaccine in the news, it can be difficult to remember a crucial fact was missing — whether people who have recovered from COVID-19 were immune to getting it again.

If protective immunity was possible, a vaccine was also likely possible. Until this week that hadn’t been established, even in animals. 

Now it has been. A study at Beth Israel Deaconess Medical Center in Boston published in the journal Science on Wednesday found that nine rhesus macaque monkeys which had recovered from COVID-19 developed natural protective immunity against re-infection with the virus.

Not all viruses generate natural protective immunity, so scientists had worried people could potentially be infected over and over again. The monkey data makes that seem less likely. 

“Our findings increase optimism that the development of COVID-19 vaccines will be possible,” said the study’s leader, Dr. Dan Barouch, a virologist who is also a professor of medicine at Harvard Medical School.

Chinese vaccine shows early promise

Chinese researchers on Friday published a study in the British medical journal The Lancet on an early candidate vaccine tested on 108 healthy adults in Wuhan, China. 

Within two weeks of getting the vaccine, the immune systems of people receiving all three doses showed some level of response, with most developing a type of antibody that can attach to the virus, though not necessarily destroy it. Some also developed so-called neutralizing antibodies, which can kill the virus. 

The vaccine is from CanSino Biologics in Tianjin, China. The trial is in the early stages and it is not yet known if the possible vaccine can generate enough of these neutralizing antibodies to protect people against the virus.

The candidate vaccine is scheduled to be tested in Canada soon. The Canadian Center for Vaccinology is working with CanSino and Canada’s National Research Council to coordinate the trial. Canadian Prime Minister Justin Trudeau made the announcement during a press briefing.

CanSino chairman Xuefeng Yu worked in Canada from 1996 to 2009.

$1.2 billion for first dibs on untried vaccine

On Thursday the United States has pledged to pay as much as $1.2 billion to get early access to 300 million doses of an experimental COVID-19 vaccine being developed and tested in England by the University of Oxford’s Jenner Institute and licensed to British drugmaker AstraZeneca.

It is expected to be delivered as early as October, though that means only that the doses will be stored until the vaccine completes clinical trials ensuring it is safe and effective in protecting against COVID-19 infection. If it isn’t, they’ll be destroyed. 

The vaccine is still in very early clinical trials in humans and is being tested for safety, whether it produces antibodies against SARS-CoV-2, the virus that causes COVID-19, and whether it protects the immunized from becoming infected with the virus. The first tests began in England on April 23.

Last week Oxford reported that a single dose of the vaccine caused six rhesus macaque monkeys to develop antibodies to coronavirus within 28 days but did not protect them from becoming infected with COVID-19.

The vaccine, called ChAdOx1, did prevent them from developing pneumonia and lung inflammatory disease when the animals were exposed to the virus.

Moderna vaccine appears safe 

On Monday, Moderna announced its candidate vaccine appeared to be safe when given to eight humans and that it stimulated an immune response to SARS-CoV-2, the virus that causes COVID-19. Experts called it a “so far, so good” finding.

Participants in the Phase 1 clinical trial tests made neutralizing antibodies to the virus. When tested on human cells in the laboratory the antibodies stopped the virus from reproducing. 

After two doses of the candidate vaccine, participants’ antibody levels were about the same as in people who have recovered from a COVID-19 infection.

There is no data yet on whether the candidate vaccine protects against becoming infected with SARS-CoV-2.

Slow is fast when it comes to vaccines

An editorial in the respected journal Science cautioned against effort to speed up testing of potential SARS-CoV-2 vaccines. SARS-CoV-2 is the virus that causes COVID-19.

While many advocates have suggested fast-tracking vaccine trials in humans, deputy editor Douglas Green says while clinical trials, especially the large-scale Phase III portion, are time consuming, they are vital to ensuring a vaccine is safe and effective.

All the vaccine candidates that have been in the news so far are in Phase 1 and Phase 2, meant to test that the vaccine itself doesn’t cause reactions and that it causes the body to mount an immune response.

Moving too fast on Phase 3 could be “catastrophic,” Green wrote. There are examples of preliminary vaccines that produced neutralizing antibodies but when large trials were conducted they made infections worse.

That happened in a 1966 trial of a vaccine against Respiratory Syncytial Virus, RVS. Subjects who got the vaccine actually did worse when infected with the virus. Green cautions that many scientists believe proper testing will mean an effective vaccine won’t be widely available for 12 to 18 months.

He quoted cancer biologist Charles Sherr, who told him, “Fast is slow, and slow is fast.”