Key points to remember
- Pfizer has been granted breakthrough therapy status for an RSV vaccine for pregnant women to help protect infants against serious RSV disease in their first year of life.
- Phase 2 clinical trial results show that the RSVpreF vaccine is effective in delivering fetal antibodies. It will now proceed to phase 3 trials.
- RSV is a common seasonal virus that can cause bronchitis and pneumonia in infants, children, and the elderly who are at high risk for severe respiratory disease.
- There is currently no vaccine to prevent RSV.
Early results from a Phase 2 clinical trial show that Pfizer’s experimental RSVpreF vaccine provides antibody protection against RSV in newborns. RSV, the respiratory syncytial virus, is a common cause of infant hospitalization and childhood pneumonia in approximately 58,000 children under the age of 5 each year.
The placebo-controlled study, which was funded by Pfizer, included 406 women ranging from 24 to 36 weeks of pregnancy. By the time 80% of participants who received the vaccine had delivered, maternal blood and umbilical cord blood were positive for both RSV antibodies. This means that infants are born with a layer of protection against future RSV infection.
“If approved by the FDA, this maternal immunization has the potential to be the first vaccine candidate to help protect infants in their vulnerable first months of life against disease caused by this highly contagious virus,” Kathrin U. Jansen , PhD, senior vice president and head of vaccine research and development at Pfizer, said in a Press release.
What is RSV and who is at risk?
RSV is a common contagious respiratory virus that circulates every year like the flu. It is a major cause of hospitalization for acute lower respiratory tract infection (bronchitis, pneumonia) in infants and children under 5 years of age.
There is currently no vaccine to prevent RSV.
According to the Centers for Disease Control and Prevention (CDC), almost all children will have an RSV infection by their second birthday.
RSV symptoms usually occur in stages and include:
- Decreased appetite
- To sneeze
- Runny nose
Although the majority of children infected with RSV have mild symptoms and make a full recovery, there is a subset of infants, children, and older adults who are at high risk for serious RSV complications resulting in hospitalization. , even death.
Infants and children with specific risk factors are more likely to develop severe RSV disease. These groups include:
- Premature infants
- Infants under 6 months
- Children with chronic lung disease
- Children with congenital heart disease
- Children with weakened immune systems
- Children with neuromuscular disorders
- Children who have difficulty swallowing
How RSV is currently treated
Most children infected with RSV recover on their own. However, for infants and children at high risk of serious complications, there is a US Food and Drug Administration (FDA)-approved drug called Synagis (palivizumab) used to prevent hospitalization of high-risk children.
Palivizumab is a monthly injection for premature babies (born 35 weeks or earlier) and babies with pre-existing conditions that put them at risk of hospitalization and serious illness from RSV infection. It is given only during the RSV season (fall, winter and spring).
A vaccine against RSV is in the works
In addition to the RSVpreF vaccine for pregnant women, scientists are also exploring an RSV vaccine for all infants and young children. Phase 3 clinical trials of nirsevimabdeveloped by Sanofi and AstraZeneca, show that the vaccine is 74.5% effective in preventing the virus in healthy, high-risk infants.
Moderna is also testing a single-dose RSV vaccine for adults over 60. Currently called mRNA-1345, the vaccine is in phase 3 clinical trials. Researchers hope this will help prevent more than 177,000 hospitalizations and 14,000 deaths associated with RSV complications in people over 65.
The RSVpreF vaccine for pregnant women will enter phase 3 clinical trials to establish whether it is safe without the chemical compound aluminum hydroxide, which was associated with local reactions and side effects in previous phases of the study. .
Currently, recommended vaccinations for pregnant women include the annual flu vaccine and the Tdap vaccine to prevent neonatal whooping cough (whooping cough).
Because clinical trials can take several years, a licensed RSV vaccine for pregnant women is still a long way off. In the meantime, people can help prevent the spread of RSV, which is transmitted through air droplets after a person coughs or sneezes, by taking common safety precautions, including:
- Wash your hands frequently
- Cover your cough and sneeze
- Avoid crowded spaces
- Wear a mask indoors
- Disinfect frequently touched surfaces
- Stay home if you are sick
If your child is at high risk for serious RSV disease, talk to your healthcare provider to see if Synagis is a preventative option during RSV season.
What this means for you
RSV is transmissible through air droplets. The best way to stop the spread is to practice good hand hygiene, avoid large crowds, and avoid sick people. If you have an infant or young child who is at risk for severe RSV disease, discuss with your healthcare provider additional ways to prevent hospitalization.