With reports of respiratory syncytial virus (RSV) cases surging among babies admitted to New Zealand hospitals, it is heartening to hear Kiwi researchers are part of a global effort closing in on a vaccine.
Numerous vaccines are in the pipeline — with many accelerating in development during the past 10 years.
Age plays a significant role in RSV, with babies typically infected in the first RSV season encountered as maternal antibodies passed to the infant from the mother decline. As the baby has yet to develop their own immune responses, this is the period severe lower airway disease can develop.
Premature babies are most at risk as they haven't received the maximum amount of maternal antibodies, nor even begun developing immune response.
Immune responses develop in the first and second years of life, building to a peak in a healthy adult who will suffer only symptoms of a common cold to RSV exposure. A vaccine could not only save the lives of babies, it could also extend life as immunity declines in old age with most RSV deaths happening in the frail and elderly.
It's high stakes. Investigations into an RSV vaccine were almost abandoned in 1966 after a US trial of formalin-inactivated RSV vaccine led to many infants experiencing worse symptoms than usual and two toddlers died.
But researchers steadily rallied, eventuating in what researcher Clarence Buddy Creech from Vanderbilt University in Tennessee referred to in 2018 as the beginning of the "golden age of RSV vaccines".
A leading candidate is MEDI8897, more lately branded as Nirsevimab. It has been developed in a partnership between Sanofi and AstraZeneca, which is the first investigational extended half-life monoclonal antibody being developed as a passive immunisation for the prevention of lower respiratory tract infections caused by RSV.
It is designed to protect all infants experiencing their first RSV season and infants with congenital heart disease or chronic lung disease entering their first and second RSV season.
Paediatric infectious disease specialists from the University of Otago are involved in trials of MEDI8897, which began recruiting patients in April 2020. Associate Professor Tony Walls this week told RNZ they were at stage three of trials, where they are trying to establish whether the vaccines actually work.
Trials have been going for five years or more. In Tasmania, a Phase 2b randomised, double-blind, placebo-controlled study was launched in 2016 to evaluate the safety and efficacy of MEDI8897 in healthy preterm infants.
On June 28, Sanofi announced Nirsevimab showed positive topline results in the second of three phases of trials and the companies plan to submit for regulatory approval in the first half of 2022.
GlaxoSmithKline and Janssen are also among the companies racing to develop a vaccine. The US National Institute of Allergy and Infectious Diseases has been trialling a protein-based vaccine known as VRC-RSVRGP084-00-VP (otherwise known as DS-Cav1) in adults.
The Bill & Melinda Gates Foundation donated $127 million in 2015 towards a Novavax vaccine aiming to protect infants by immunising the mothers. This struck a major obstacle with a phase 3 trial failure in older adults a year later but is still pressing on in the hope the aluminium-adjuvanted RSV F vaccine ResVax will be successful.
As an interesting aside, the early breakthroughs as well as failures with RSV vaccines - as well as work on the dengue virus, SARS-CoV and Middle East respiratory syndrome coronavirus - were instrumental in assisting in the hunt for Covid-19 vaccines. Given this success, and the promising clinical trial results piling up, there is every hope of defeating this terrible blight within the next few years.