Oxford's Covid-19 vaccine appears safe, but more research needed

Results from trials involving three different coronavirus vaccines released, all showing positive results, with evidence the vaccines can produce immune responses that would be expected to protect people against infection.

They all also appeared to be safe, although it will take studies with more people to show how safe they really are and whether they can prevent infection.

Early results of a closely watched Phase 1/2 trial published in The Lancet suggest a coronavirus vaccine developed by the University of Oxford and AstraZeneca is safe and induces an immune response. However, researchers stressed more study is needed to know whether the vaccine protects people against the virus.

Phase 2 results for one vaccine candidate made by Chinese company CanSino Biologics were also published in the medical journal The Lancet and early results from Phase 1/2 trials of the vaccine made by Pfizer and BioNTech were released in a pre-print paper that has not yet been peer-reviewed.

That's good news, researchers said. "The immune system has two ways of finding and attacking pathogens -- antibody and T cell responses. This vaccine is intended to induce both, so it can attack the virus when it's circulating in the body, as well as attacking infected cells," University of Oxford pediatrician Dr. Andrew Pollard, the study's lead author, said in a statement.

The Oxford vaccine prompted an antibody response within 28 days and a T-cell response within 14 days, according to the results published Monday. Neutralizing antibodies -- so-called because they can neutralize the virus -- were detected in most participants after one shot, and in all of them after two.

"We hope this means the immune system will remember the virus, so that our vaccine will protect people for an extended period. However, we need more research before we can confirm the vaccine effectively protects against SARS-CoV-2 infection, and for how long any protection lasts."

It's also not clear how well the vaccine would perform in older people who are more at risk of severe disease from Covid-19.