How our immune system reacts to COVID-19 variants

Scientists from Kids Research, SCHN, in partnership with the University of Sydney, the Kirby Institute at UNSW Sydney, Australian Red Cross Lifeblood, St Vincent’s Hospital, NSW Health Pathology and other collaborators, have undertaken one of the world’s most comprehensive studies of the body’s own immune response against COVID-19 infection.

The study is an important lesson in vaccine design and development, revealing that vaccination is more effective than the body’s natural immune response following infection, and shows the need to invest in new vaccine designs to keep pace with emerging COVID variants.

The research team analysed the serum (the part of blood that contains crucial information about the immune system) of 233 COVID-19 infected individuals over 7 months and uncovered that the level of immunity over time depends on the severity of the disease, and the type of variant contracted.

Antibodies developed during the first wave had reduced effectiveness against six variants, including those observed in the second wave here in Australia, through to three other variants of concern from the UK, Brazil and South Africa.

Co-senior author, Associate Professor Fabienne Brilot of Kids Research, SCHN and the University of Sydney, led the analysis branch of the study. Her team’s research found that current vaccines are helpful, but development must continue.

“We can learn a great deal from these people who were infected in the first wave in Australia as they were infected with the same variant that our current vaccines are based on,” said Associate Professor Brilot.

“While the approved vaccines are showing good responses, our study highlights the importance of continued vaccine development, especially taking into account the differences in variants.”

“What this work has shown us is that current observations about vaccines show they offer a much broader protection against COVID-19 and its variants than the body’s natural immune response following infection, which is usually only protective against the variant of the virus that the person was infected with. We, therefore, should not rely on the body’s natural immune response to control this pandemic, but rather the broadly protective vaccines that are available," she said.

The study of many global viral variants was made possible by the key collaboration between NSW Health Pathology and The Kirby Institute. The latter team engineered cells to rapid catch virus from swabs that were acquired and rapidly sequenced by the team at Prince of Wales headed by Professor William Rawlinson.

Co-first author, Fiona Tea, completed the research as part of her postdoctoral fellowship at the University of Sydney and Kids Research at SCHN said that a key component of this research is the detail of the study of antibodies in people recovering from COVID-19.

“What makes this study stand out is the level and depth of analysis to neutralising antibody levels in people recovering from COVID infection over time, including comparison of infection recovering from different viral variants,” she said.

This study was supported by Snow Medical and various grants, including two NSW Health COVID-19 Research Grants, designed to fund research projects in priority areas to support the NSW Health response to COVID-19.

Find more information, including further details on the study process, on the Kids Research website.