New insights into respiratory syncytial virus and prevention strategies

Respiratory syncytial virus (RSV) is a major cause of respiratory infections, particularly in infants, children under 5 years, and older adults. Its rapid spread makes RSV a serious public health concern. Currently, there are no effective medications for RSV, and current treatment focuses on providing supportive care and preventing its spread.

In a recent study, authors from the Chinese Academy of Medical Science and Peking Union Medical College, Nanjing Medical University, Children's Hospital of Chongqing Medical University, National Institute for Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention and Beijing Children's Hospital China, provide a comprehensive review of RSV's virology, clinical impact, and prevention strategies. The review, published in the Chinese Medical Journal, highlights the urgent need to develop safe and effective vaccines to mitigate this critical health need for infants, children, and older adults at risk.

RSV, the causative factor behind respiratory infections, is a virus made of ribonucleic acid (RNA) and proteins that allows it to latch onto and invade healthy cells. These proteins are the key targets for developing vaccines and treatments, though they can evolve over time. Once RSV hooks onto a cell, it changes its shape, injecting its genetic code to take over and spread its infection. "RSV's most essential surface glycoproteins are the G and F proteins, which play crucial roles in virus attachment to host cells and cell fusion and are vital transmembrane proteins on the virus surface," says the authors. Once inside the host cells, the virus multiplies rapidly, spreads to other cells, and disrupts the immune response, leading to inflammation, mucus buildup, and lung damage. Long-term complications of RSV infections include an increased risk of asthma.

Although RSV can affect people of all ages, it is most severe in infants and older adults above the age of 75 years. The disease burden is particularly severe in low and middle-income countries, where RSV causes high hospitalization and mortality rates. Countries such as China, India, Indonesia, Nigeria, and Pakistan account for majority of the global cases of RSV-associated acute lower respiratory infection. Infants born prematurely or with pre-existing conditions like bronchopulmonary dysplasia, Down syndrome, and congenital heart disease are at higher risk of RSV infections than the rest. RSV frequently goes undetected in adults due to delayed symptoms and irregularity in testing. Older adults, especially those with pre-existing health conditions, face complications such as pneumonia, respiratory failure, and even heart failure. It is essential to tailor healthcare services and immunization strategies to local conditions, as RSV circulates seasonally-;peaking in winter in temperate regions and during rainy seasons in tropical areas. In most parts of China, RSV typically circulates from November to March, while regions closer to the equator experience longer and less distinct RSV seasons.

During the pandemic, efforts to curb the epidemic of SARS-CoV-2 had significantly reduced the RSV infections. This led to a change in its seasonality and distribution across the various age groups. However, after the COVID-19 pandemic, RSV resurged again, even surpassing its previous levels. "RSV has a wide range of pathological impacts that extend beyond the respiratory system, potentially affecting multiple organs and leading to various complications. In terms of respiratory complications, potential issues include respiratory failure, acute respiratory distress syndrome, pulmonary consolidation, and atelectasis" highlights the authors. RSV also affects the cardiovascular system, triggering premature heart beats and potentially leading to heart failure. It also affects the digestive system, causing symptoms that range from vomiting and diarrhea to severe intestinal injury.

Although some studies showed that ribavirin and interferon have a certain degree of efficacy in certain populations, there is currently no specific drug for respiratory syncytial virus. Vaccine development began since 1960s but faced setbacks. However, with technological advancements, new vaccines and monoclonal antibodies targeting specific age groups and health conditions are emerging. Two monoclonal antibodies designed for infants, palivizumab and nirsevimab, along with three vaccines for older adults, namely RSVPreF3, RSVPreF, and mRNA-1345, and one vaccine for maternal populations, RSVPreF, have been authorized for use in certain regions. This marks a significant breakthrough in the prevention of RSV.

"Concurrently, emphasis should be placed on elevating the awareness of professionals and the public regarding RSV infection and the value of vaccination," concludes the authors. At the individual level, using masks, ensuring clean air conditions, and maintaining hygiene like frequent hand wash, should be followed. At the wider community level, dissemination of information regarding public health, setting up dedicated wards for RSV patients, and quickly assessing outbreaks while following health protocols are crucial steps to curb the virus.