Following the news that AstraZeneca and Oxford University published Phase I/II results of their COVID-19 vaccine candidate ChAdOx1/AZD1222;

Philipp Rosenbaum, PhD, Senior Infectious Diseases Analyst and Michael Breen, PhD, Director of Infectious Diseases at GlobalData, a leading data and analytics company, offer their view:

Rosenbaum commented “The vaccine developed by Oxford University in collaboration with AstraZeneca showed good tolerability and safety in Phase I/II, especially when given with paracetamol. The 1% of trial participants who received a second dose of the vaccine showed three to six times more antibodies against the virus, giving the company a possible direction for the next Phase II/III studies.

“Unlike CanSino, Moderna and Pfizer, AstraZeneca and Oxford University only tested one high-dosage formulation of the vaccine, providing less data on the optimal relation of antibody response induction to acceptable side effects. However, as AstraZeneca argued in the publication, a single higher dose with possibly higher reactogenicity might be more useful in a pandemic situation in which a quick response to protect the population is needed.”

Breen added “While this data is highly encouraging, we have now seen promising data from multiple companies. It is not yet clear who is in the lead, as immunogenicity and B-cell and T-cell responses are nice to see, and support continued development, but none of these data paint a clear picture of a winner. There is ultimately one key piece of data that we are waiting on, and that’s protection against disease.

“We also need to keep in mind that protection is not a simple binary endpoint that answers a single question, such as ‘did people get the disease or not?’. What if a vaccine is not terribly effective in reducing prevalence, but has significant effects on reducing morbidity and mortality? What if one vaccine is more effective in preventing disease in older patients and those with comorbidities who are might likely to suffer severe effects from COVID-19? What if one vaccine looks like it confers protection for a significantly longer period of time? These questions all take time to answer and must be properly interrogated through clinical trials, and even though we might have one or acceptable vaccines in the clinic at present, we shouldn’t declare a winner until we have these questions answered.”