Speaking at the newspaper’s annual Tech Live conference, Bancel also said sufficient interim results from the study takes longer to get and that the government’s permission to use the vaccine may not come until next year.

The first interim analysis of the vaccine’s efficacy will happen when 53 people in the entire study get symptomatic COVID-19, the report said, Reuters reported.

“That first analysis is likely to occur in November, but it’s hard to predict exactly which week because it depends on the cases, the number of people getting sick,” the report quoted Bancel as saying.

Bancel had told Financial Times here last month that Moderna would not be ready to apply for emergency use of its COVID-19 vaccine before Nov. 25 at the earliest.

Bancel also highlighted that a ramping up of production is a challenge. “If one ingredient is missing, we cannot make the vaccine,” as per the Journal’s report.

Moderna is on track to produce 20 million doses of its experimental vaccine by the end of the year, the company had said last month, adding that 25,296 participants had enrolled out of a planned 30,000 in its late-stage study.

Drugmakers are racing to develop a COVID-19 vaccine, with more than 150 potential vaccines being developed and tested globally.

Besides Moderna, Pfizer Inc, and AstraZeneca Plc, among others, are front-runners to develop the vaccine.

The fact that the vaccine prevented the virus from replicating in the nose is seen as particularly crucial in preventing it from being transmitted onward to others.

The same outcome did not occur when the University of Oxford’s vaccine was tested on monkeys, though that vaccine did prevent the virus from entering the animals’ lungs and making them very sick.

In the Moderna animal study, three groups of eight rhesus macaques received either a placebo or the vaccine at two different dose levels – 10 micrograms and 100 micrograms.

All vaccinated macaques produced high levels of neutralizing antibodies that attack a part of the SARS-CoV-2 virus used to invade cells.

Notably, monkeys receiving both dose levels produced these antibodies at levels higher than those found in humans who have recovered from COVID-19.

The authors reported that the vaccine also induced the production of a different immune cell known as T-cells that may have helped boost the overall response.

A major area of concern is that vaccines under development could actually backfire by amplifying rather than suppressing the disease.

So-called vaccine-associated enhancement of respiratory disease (VAERD) has been linked to the production of a specific type of T-cell known as Th2 – but these cells were not produced during the experiment, suggesting this vaccine won’t backfire.

Four weeks after the monkeys received their second injection, they were exposed to the SARS-CoV-2 virus, both through the nose and directly to the lungs via a tube.

After two days, no replicating virus was detected in the lungs of seven of the eight macaques in both the low and high dose groups.

By contrast, all eight in the placebo group continued to have the virus present.

None of the eight macaques in the high dose groups had detectable levels of virus in their noses two days after exposure.

“This is the first time an experimental COVID-19 vaccine tested in nonhuman primates has been shown to produce such rapid viral control in the upper airway,” said the National Institutes for Health, which co-developed the vaccine, AFP reported.

A COVID-19 vaccine capable of stopping the virus in the lungs will prevent the disease from becoming severe, while stopping the virus from replicating in the nose would lessen transmission.

The Moderna vaccine uses genetic material in the form of viral RNA to encode the information needed to grow the SARS-CoV-2 spike protein inside the human body to trigger an immune response.

Spike proteins give coronaviruses their crown-like appearance and are used to invade human cells, but by themselves are thought to be relatively harmless.

The advantage of this technology is that it bypasses the need to manufacture viral proteins in the lab, helping to ramp up mass production.

Both Moderna’s vaccine and the vaccine co-developed by the University of Oxford and AstraZeneca have entered late-stage human trials.

The Phase 3 trial will recruit 30,000 participants in the US, with half to receive the vaccine at 100 microgram dose levels, and the other half to receive a placebo.

It is designed to show whether the vaccine is safe and can prevent infection by the SARS-CoV-2 virus, or if people still get infected whether it can prevent the infection from progressing toward symptoms.

If they do get symptoms, the vaccine can still be considered a success if it stops severe cases of COVID-19.

The study should run until October 27, according to its page on clinicaltrials.gov.

The announcement came after the New England Journal of Medicine on Tuesday published results from the first stage of Moderna’s vaccine trial, which showed the first 45 participants all developed antibodies to the virus.

Moderna, currently in the middle stage, is considered to be in a leading position in the global race to find a vaccine against the coronavirus, which has infected more than 13.2 million people and killed 570,000.

China’s SinoVac is also at Phase 2.

Russian news agency TASS on Sunday announced Russian researchers have completed clinical trials on a vaccine, though they have not shared their data.

Scientists caution that the first vaccines to come to the market may not be the most effective or safest.

Moderna had previously published “interim results” from the first stages of its trial, called Phase 1, in a press release on its website in May.

These revealed the vaccine had generated immune responses in eight patients, a result called “encouraging” by Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, which is co-developing the vaccine.

But some in the scientific community said they would reserve judgment until they saw the full results in peer-reviewed form.

According to the new paper, 45 participants were split into three groups of 15 each to test doses of 25 micrograms, 100 micrograms, and 250 micrograms.

They were given a second dose of the same amount 28 days later.

After the first round, antibody levels were found to be higher with higher doses.

Following the second round, participants had higher levels of antibodies than most patients who have had COVID-19 and gone on to generate their own antibodies.

More than half of the participants experienced mild or moderate side effects, which is considered normal.

The side effects included fatigue, chills, headache, body ache, and pain at the injection site.

Three participants did not receive their second dose.

They included one who developed a skin rash on both legs and two who missed their window because they had COVID-19 symptoms, but their tests later returned negative.

“The results look pretty good and look pretty consistent,” David Lo, a professor of biomedical sciences at the University of California Riverside told AFP.

But he cautioned that more work was needed to evaluate the vaccine’s safety including making sure that it did not backfire by eventually making the immune system “tolerant” toward the real virus.

Amesh Adalja, an infectious disease specialist at Johns Hopkins University, added it was encouraging that the participants developed high levels of an advanced class of antibodies.

He added, however: “You have to be very limited in how much you can extrapolate from a phase one clinical trial because you want to see how this works when a person is exposed to the actual virus.”

The Moderna vaccine belongs to a new class of vaccine that uses genetic material in the form of RNA to encode the information needed to grow the virus’s spike protein inside the human body, in order to trigger an immune response.

The spike protein is a part of the virus that it uses to invade human cells, but by itself, the protein is relatively harmless.

The advantage of this technology is that it bypasses the need to manufacture viral proteins in the lab, shaving months off the standardization process, and helping to ramp up mass production.

No vaccines based on this platform have previously received regulatory approval.