The results are likely to be closely examined, particularly in Canada, which recently announced it would test the vaccine and produce it there if results of the early studies were positive. A few, including CanSino's, have moved to larger mid-stage studies that are evaluating safety and the ability to induce an immune response. But about half of the volunteers - people who already had immunity to the virus used in the vaccine - did not respond as well.
Although these studies don't prove that humans and develop an immunity to the virus after recovering, it's definitely a step in the right direction. Further trials are needed to tell whether the immune response it elicits effectively protects against SARS-COV-2 infection, said the medical journal.
With only four or five animals getting each vaccine, comparisons need to be treated with caution, but the monkeys receiving certain vaccines showed dramatically lower levels of virus throughout their bodies compared to the controls. Two papers, published back-to-back in Science this week are some of the first to show that non-human primates can develop protective immunity to SARS-CoV-2-a finding critical for vaccine and public health strategies.
But the potential vaccine is far from being made available for widespread use.
Gary Kobinger, director of the Infectious Disease Research Center at Laval University in Quebec, was not surprised by the findings.
A majority of participants also produced virus-fighting T cells two weeks after taking the vaccine, which were also greatest at the higher dose levels.
Encouragingly, none of the 108 patients had serious side effects.
The most common adverse reactions were mild pain at the injection site reported in over half (54pc, 58/108) of vaccine recipients, fever (46pc, 50/108), fatigue (44pc, 47/108), headache (39pc, 42/108), and muscle pain (17p, 18/108).
All of the macaques were infected with the new coronavirus six weeks after vaccination, and those that had received the real vaccines produced levels of antibodies in their blood that were high enough to neutralize the virus within two weeks. They also said they will follow up with participants for at least 6 months to provide more data.
In a separate study that included numerous same researchers, titled "DNA vaccine protection against SARS-CoV-2 in rhesus macaques", the team developed a series of DNA vaccine candidates expressing different forms of the SARS-CoV-2 Spike (S) protein and evaluated them in 35 rhesus macaques (25 adult rhesus macaques with the investigational vaccines and 10 animals received a sham control). "It's the concern with Ad5 that's been there from the beginning: That if you have antibody to the vector, then you don't get as good a [vaccine] take". "I don't know", she added. "It's only a Phase 1 study".