In the phase 1 trial, they said the overall incidence of adverse reactions was similar in the low- and high-dose groups at both vaccination schedules, with the most common symptom being a pain at the injection site.
Now, researchers have released preliminary results that show the vaccine produces an immune response, although it's too early to say whether it can prevent disease.
Pfizer's vaccine must be stored and transported at minus 70 deg C, though it can be kept in a normal fridge for up to five days, or up to 15 days in a thermal shipping box.
In contrast, vaccines developed by Pfizer/BioNTech and Moderna use a new technology called synthetic messenger RNA to activate the immune system against the virus and require far colder storage.
And given the United Kingdom has bet most heavily on the Oxford vaccine in terms of investment and numbers of doses ordered, a positive result will be the Christmas present we've all been waiting for.
Sinovac's Phase 1 trial began in April with 144 participants, and its Phase 2 trial began in May with 600 people.
The study's participants in the oldest age group had an average age of 73 to 74 and few had underlying health conditions, so the older age bracket was excluded as were those living in residential care homes.
The global goal for the clinical trial is 60,000 participants.
Professor Sarah Gilbert, a co-author of the report and professor of vaccinology at Oxford University pointed to these limitations. "Studies suggest T cells play a large role in immune response to the coronavirus, [and] what kind of role they play [is] being investigated". The level of antibodies induced by the vaccine was lower than those in people who had recovered from Covid-19, whereas it was capable of protecting the human body from infections caused by the virus, state-run Xinhua reported, citing the Lancet findings.
But today's evidence from Oxford isn't the same.
The researchers also stress that 240 participants were over the age of 70 and their immune responses were similar to younger people in this clinical trial as well as the results from the younger cohort from Phase I. This is a very important result given how older adults are one of the most-at-risk groups.
Dr Maheshi Ramasamy, Investigator at the Oxford Vaccine Group and Consultant Physician said in a statement, "Older adults are a priority group for COVID-19 vaccination because they are at increased risk of severe disease, but we know that they tend to have poorer vaccine responses". These Phase 2 results show that this was not the case for the Oxford vaccine. "It is essential that a COVID-19 vaccine can be effective across a broad age range particularly in older individuals where they are disproportionately at risk of COVID-19 disease".