A new study, "Respiratory Syncytial Virus Prevention Within Reach: The Vaccine and Monoclonal Antibody Landscape," published in The Lancet Infectious Diseases, reviews recent developments in the respiratory syncytial virus (RSV) vaccine and monoclonal antibody strategies.
Such reviews help provide new insights into the research landscape guided by the failures and lessons from previous clinical trials. The study reviewed a total of 19 vaccines, of which 11 of them are still under development. Meanwhile, 19 new vaccines have just entered the testing phase.
Who Needs the Respiratory Syncytial Virus (RSV) Vaccine?
According to the British Society for Immunology, RSV is a major cause of childhood and old age disease, with an estimated 160,000 to 200,000 deaths globally. Most children are exposed to RSV within the first two years of their lives with a lifelong re-infection risk. However, full and long-lasting immunity does not develop despite repeated exposure, even though most have anti-RSV antibodies.
To date, there is no specific treatment for RSV yet, but the monoclonal antibody Palivizumab can be used to prevent the infection. RSV largely infects the epithelial cells in the lungs via the F and G glycoproteins and attaches to its target cell, wherein the infected cell could merge and form syncytia.
Vaccines are needed to target at-risk groups, especially infants between 0-6 months, who are at the greatest risk of severe RSV disease. However, their immature immune system makes vaccination a challenge.
On the other hand, children over six months respond better to vaccination. They represent a significant group of a reservoir of infection for newborns, so a vaccine for them is necessary to reduce the risk of RSV.
Moreover, pregnant women can also be targeted to induce immunity and passively transfer their antibodies to infants via the placenta and breast milk after birth to protect infants during the first few months of life.
Lastly, the elderly with an aging immune system should also be targeted when developing RSV vaccines. Their immune system needs to be boosted to protect them from serious complications from the infection.
RSV Vaccine and Monoclonal Antibodies in Development
News Medical Life Sciences reported that eligible groups should receive appropriate vaccines. For babies up to six months old, mAbs are preferred, while LAVs are for older infants. Meanwhile, pregnant women may be given pre-fusion sub-unit vaccines, while sub-unit, NA, and viral vector (VV) vaccines are for older adults.
The same researchers of the current study have also examined previous late-phase clinical trial failures. Here are the previous and current vaccine and antibody strategies they reviewed:
Previous Clinical Failures
- PREPARE - This involves maternal RSV vaccine that entered Phase III clinical trial that met the safety criteria and provided protection against severe infection to infants. But it did not meet the pre-set efficacy criteria.
- REGN2222 - It is a mAb called suptuvumab that failed to prevent RSV hospitalizations during a multinational Phase III clinical trial.
- ChAd155.RSV - It halted after a Phase II trial for showing no evidence of adequate efficacy, although it is found to be safe and effective in human adults.
Current RSV Vaccine and Antibody Strategies Under Review
- LAVs
- Chimeric live virus vaccine
- Protein subunit vaccines
- Particle-based vaccines
- NA vaccines
- Recombinant VV vaccines
- mAbs
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