Brazilian pediatrician Monica Levi, one of the volunteers who received the COVID-19 vaccine, works at the Specialized Clinic for Infectious and Parasitic Diseases and Immunizations (CEDIPI) in Sao Paulo, Brazil on July 24, 2020. The doctor is one of the 5,000 volunteers who took part in the phase 3 trials in Brazil – the last before homologation – of the ChAdOx1 nCoV-19 vaccine developed by Oxford University in cooperation with the British pharmaceutical company AstraZeneca.
Nelson Almeida | AFP | Getty Images
LONDON – The coronavirus vaccine developed by Oxford University and AstraZeneca is safe and elicits a similar immune response in all adults, according to preliminary results from an expert-reviewed phase 2 study.
The promising early-stage results were published Thursday in The Lancet, one of the world's leading medical journals.
The study of 560 healthy adults, including 240 over 70 years of age, found the vaccine to be safe and produce a similar immune response in people over 56 years of age and between 18 and 55 years of age.
Elderly people are exposed to a "significant risk" of developing a serious illness when contracting Covid-19, according to the WHO, citing decreased immune function and possible underlying health conditions. However, people of all ages are at risk of contracting the virus.
UK pharmaceutical company AstraZeneca, which works in partnership with Oxford University, previously said preliminary data showed that its experimental vaccine had triggered an immune response in older and younger adults.
A safe and effective vaccine is seen by many as a trailblazer in the fight against the coronavirus pandemic, which killed over 1.3 million people worldwide.
Major challenges remain before a vaccine can be introduced. The global battle to secure potential deliveries has raised the alarm about fair access while questions about logistics, distribution and costs remain open.
The Oxford vaccine candidate was found to produce few side effects and trigger immune responses in both parts of the immune system in all age groups and at low and standard doses.
Preliminary results indicated that the vaccine – ChAdOx1 nCoV-19 – elicited what is known as a "T-cell response" within 14 days of the first dose and an antibody response within 28 days of the booster dose. Scientists expect T cell responses to play a role in long-term immunity to the virus.
Dr. Maheshi Ramasamy, co-author of the study at Oxford University, said the antibody and T-cell responses in older adults were "robust" and "encouraging".
"The populations at greatest risk of developing severe COVID-19 disease include people with existing health conditions and older adults," Ramasamy said.
"We hope this means that our vaccine will help protect some of the most vulnerable people in society. However, more research is needed before we can be sure."
The Oxford study authors said their results could be encouraging if it is found that immune responses are linked to protection against Covid-19 infection. However, the phase 2 study did not evaluate the vaccine's effectiveness and phase 3 studies are currently being conducted to confirm this.
Results are expected later this year depending on the rate of infection in clinical study communities.
The authors noted several limitations to their study, including that participants in the oldest age group had a mean age of 73 to 74 years with few underlying health conditions, and almost all participants were white and nonsmokers.
People from different backgrounds, countries and ethnic groups are said to have been included in the phase 3 study.
The study comes days after two other vaccine manufacturers announced encouraging results from Phase 3 trials. They said their experimental vaccines had been shown to be highly effective against the coronavirus, adding to optimism at a time when healthcare systems in Europe and the US are once again on the verge of crisis.
Pfizer and BioNTech said Wednesday that final analysis showed their vaccine candidate was 95% effective against Covid-19 and appeared to ward off serious illnesses. Earlier this week, Moderna announced that preliminary phase three data showed the vaccine was 94.5% effective.