The Pirbright Institute, working in collaboration with the University of Oxford, announced on Tuesday that two doses of an experimental COVID-19 vaccine successfully produced a greater antibody response than a single dose in pigs.
The Surrey, England institute released research showing that two doses of the ChAdOx1 nCoV-19 (AZD1222) vaccine revealed a “marked increase of neutralising antibodies,” which bind to the virus to block infection.
The same investigational vaccine previously protected six monkeys from pneumonia caused by the virus. The ChAdOx1 nCoV-19 vaccine is made from the ChAdOx1 virus, a weakened version of the common cold that has been genetically changed so that it is impossible for it to replicate in humans, according to the Oxford researchers.
It is not yet known what level of immune response will be required to protect humans against SARS-CoV-2, according to a statement from The Pirbright Institute.
Vaccine trials in humans are underway, and the research is said to offer important findings because it reveals two doses of the new vaccine could offer more protection than one dose.
“These results look encouraging, that administering two injections with the same vaccine boosts antibody responses that can neutralise the virus, but it is the response in humans that is important,” said Bryan Charleston, professor and director of The Pirbright Institute.
Charleston said the pig proved to be a valuable model for testing human vaccines due to greater physiological similarities (like body weight and metabolic rate) as opposed to other animals.
The ChAdOx1 nCoV-19 also demonstrated T cell responses, which the lead study author, Professor Simon Graham, called “very encouraging.”
“It is likely that a combination of these responses would act in synergy to prevent and control infection, as we and others have recently shown in the context of experimental flu vaccines,” Graham said.
The news comes after Barry Bloom, immunologist and professor of public health at the Harvard T.H. Chan School of Public Health in Boston, told USA Today earlier this month that almost all of the vaccine developers are considering two shots in their regimens.
According to the outlet’s report, the first shot in the series would “prime the immune system” to help the body recognize the virus, followed by a second shot to “strengthen the immune response.”
After the first dose of a vaccine, the immune system develops antibodies and immune cells in about 14 days, says L.J. Tan, chief strategy officer with the Immunization Action Coalition and co-chair of the National Adult Immunization Summit and National Influenza Vaccine Summit.
While, at this point, it’s largely unclear precisely how long antibodies could offer immunity against COVID-19, researchers from St. George’s, University of London said the pathogen-neutralizers may remain stable in an infected person's blood for two months after diagnosis.
Fox News' James Rogers and Christopher Carbone contributed to this report.