COVID-19 Vaccine Trial in Pigs Shows Promise with 2 Shots

In a pig trial of AstraZeneca 's experimental COVID-19 vaccine, two doses of the shot shows a higher antibody response than a single dose.

Research published by the British Pirbright Institute on Tuesday showed that providing an initial prime dose accompanied by a booster dose of the vaccine resulted in a better immune reaction than a single dose. This indicates that a two-dose strategy could be more successful in providing defense against COVID-19, a disease triggered by the current coronavirus.

"The researchers saw a marked increase in neutralising antibodies, which bind to the virus in a way that blocks infection," the Pirbright team said in a statement. They added, however, that it is not yet known what level of immune response will be required to protect humans.

ChAdOx1 nCoV-19 vaccine, also known as AZD1222, was initially created by scientists at Oxford University who are now collaborating with AstraZeneca on growth and manufacturing.

"These findings seem promising that the administration of two injections ... improves the antibody response that can neutralize the virus, but the response in humans is significant," said Bryan Charleston, Pirbright's director.

AZD1222 is already in human trials, and AstraZeneca says it hopes to have data on efficacy later this year.

Preliminary data from the trial in six monkeys found that some single-shot monkeys developed antibodies to the virus within 14 days, and all of them developed protective antibodies within 28 days.

More than 100 potential vaccines are being developed around the world to try to control the pandemic that has killed hundreds of thousands of people.

Stephen Griffin, an associate professor at Leeds University who was not directly involved in this work, said it was "an encouraging advance" and showed that "a so-called ‘prime-boost’ strategy gives rise to far better responses" than a single dose.

"Whilst these studies will need to be repeated within human subjects...this is a heartening study," he said.

Source: Reuters