September 22, 2021
Peter Ben Embarek of the World Health Organization holds up a chart showing possible pathways of transmission of the coronavirus to humans, during a press conference in Wuhan, China, on February 9.

WHO says an “intermediary host species” is most likely how Covid-19 was introduced to humans

Professor Andrew Pollard, director of the Oxford Vaccine Group, receives the AstraZeneca Plc and the University of Oxford Covid-19 vaccine at Churchill Hospital in Oxford, England, on January 4. Steve Parsons/PA Wire/Bloomberg/Getty Images

The results of the South African study, which suggest the Oxford/AstraZeneca vaccine offers reduced protection from the Covid-19 variant first identified there, are in many ways “exactly what we would have expected,” Chief Investigator on the Oxford vaccine trial Professor Andrew Pollard said Tuesday.

I think that is perhaps the clue to the future here: That we are going to see new variants arise and they will spread in the population — like most of the viruses that cause colds every winter — but as long as we have enough immunity to prevent the severe disease, hospitalizations and death then we are going to be fine in the future in the pandemic,” Pollard told BBC Radio 4.  

Early data released Sunday suggest two doses of the Oxford/AstraZeneca Covid-19 vaccine provided only “minimal protection” against mild and moderate Covid-19 from the variant first identified in South Africa. The full study, which has not been released, included about 2,000 volunteers who were an average of 31 years old; about half received the vaccine and half received a placebo.

Pollard said the study in South Africa “absolutely confirms what we know about the biology of the virus, it has to transmit between people to survive and it has to mutate to do that and it’s done that in South Africa already and that will affect mild disease in people that have been vaccinated.”

“The really important point though is that all vaccines – everywhere in the world where they’ve been tested – are still preventing severe disease and death,” Pollard stressed.

He said the “jury is out” on whether the world needs need new vaccines to counter variants, but that developers are preparing them in case we do.

South African health officials said Sunday they have paused the start of a mass rollout of the Oxford/AstraZeneca vaccine to gather data on hospitalization rates and to see how effective the vaccine is in preventing severe disease in people infected with the South African variant.

Pollard said the South African government has “correctly” rethought how it will deploy the vaccine after originally aiming it first at health care workers.

He also highlighted that the South Africa study was a small study that looked at young adults who only get mild infections.

What we anticipated in that setting is the virus would still be able to cause infections that are very mild and that’s exactly what we’ve seen in that study,” Pollard said.

“We are the only people so far who have a study that looks at that variant in a population of young people and it’s telling us about the future of this virus — that it will find ways to transmit and cause mild infections, colds and so on, in the population,” Pollard said. 

“The really important question is about severe infection and we didn’t study that in South Africa because that wasn’t the point of the study,” he added, noting that “we were specifically asking questions about young adults.”

Commenting on the scrutiny the Oxford/AstraZeneca vaccine has received, Pollard said that “it’s a bit perplexing to find ourselves in the middle of political debate… we’ve made a huge effort here at the University of Oxford to be transparent in everything that we do.”