Respiratory syncytial virus (RSV) is a highly contagious respiratory disease responsible for more than 30 million acute infections in children every year and 160,000 deaths—mostly in low and middle-income countries. As a result, it is most often discussed in terms of infant care. However, data shows elderly adults are also particularly vulnerable to RSV, making the need for a vaccine that much more urgent.
The realization that RSV is widespread in older adults is relatively new. For decades, the virus, which manifests with cold-like symptoms, was often mistaken for the flu.
However, the development of influenza treatments, and the need to verify the presence of influenza over other viruses is helping physicians more accurately categorize their patients’ illnesses. It’s also providing greater clarity about the need for an RSV vaccine.
While many times patients’ symptoms are the result of a random virus, the diagnostics show a surprisingly high prevalence of RSV. Among healthy adults, RSV symptoms are usually relatively mild, but in older adults, and those with underlying heart or lung conditions, the infection can be deadly. Each year, roughly 177,000 older adults are hospitalized, and 14,000 of them die in the United States alone due to an RSV infection.
Because the virus is so contagious, it can spread rapidly in nursing homes and assisted living facilities, putting whole communities at risk.
Tricky to pin down
The good news is that the ability to accurately diagnose RSV and the growing body of data showing RSV infection trends among older people has spurred increased investment in RSV treatments and vaccines suitable for these patients. There are up to 60 vaccines currently in development with 16 candidates in clinical development.
The bad news is that despite years of research, none of these vaccine candidates have made it to market. The slow rate of progress is due to a number of challenges. In the 1960s, an RSV vaccine was produced that actually increased the rate of illness and caused two deaths, making some people in the healthcare community skittish about new developments in this area.
This virus is also difficult to work with. Developers have struggled to select the right pathway for these vaccines, and because the protective antibodies are not well understood, developers have less data to support a move from phase 2 to phase 3 studies. Animal models of efficacy have also been less consistently predictive for human subjects, adding additional levels of uncertainty – and cost -- to the development process.
Identifying patients with RSV has also been challenging for these trials. Healthy adults with RSV may never see their doctors, which means they aren’t easily identified for trial participation. However the use of population healthcare data and analytics tools may make it easier to find physicians treating these patients in the future, and to track infection trends as a way to speed recruiting.
Despite all of these obstacles, the commercial demand for an RSV vaccine – and the lack of any current vaccines or treatments -- is incentive enough for developers to push on in search of a solution. To date, none are close to commercialization, but several large pharma and smaller biotech companies are currently running RSV vaccine projects targeting both children and older adults.
VBI Vaccines has begun work on an RSV vaccine candidate using its enveloped virus-like particle (“eVLP”) platform. The project is funded in part by Canada’s National Research Council-Industrial Research Assistance Program.
The National Institute of Allergy and Infectious Diseases (NIAID), launched a clinical trial in 2018 of an investigational vaccine designed to protect against RSV in adults. The Phase 1 study at the Cincinnati Children’s Hospital Medical Center will enroll a small group of healthy adult volunteers to examine the safety of an experimental intranasal vaccine and its ability to induce an immune response.
Biotech companies Arsanis and Adimab, are partnering to develop an RSV treatment using monoclonal antibodies (mAbs) with support from the Gates Foundation.
In May, 2018, Pfizer launched a Phase 1/2 trial of its RSV vaccine candidate in healthy adult volunteers. The randomized, placebo-controlled, observer-blind, dose-ranging study will include two age groups enrolled in parallel to support both maternal and older adult indications.
Despite the slow progress I’m optimistic that a vaccine will be ready for approval in the coming years. In the meantime, raising awareness about RSV risks, reducing inappropriate use of antibiotics to treat viruses, and encouraging testing to verify the disease will all help bolster awareness of the need for this research, and accelerate new solutions to market.