As a prophylaxis for infants
Antibodies are designed to prevent RSV infection
03/08/2022 08:53 (updated)
The majority of children become infected with the so-called respiratory syncytial virus in the first two years of life. About two percent of them require hospital treatment. A new antibody that is given prophylactically should be able to prevent this.
Almost all toddlers get stuck with it in the first two years of life Respiratorischen Synzytial-Virus (RSV) on. A new active ingredient is intended to protect infants from serious consequences of respiratory infections. In an international study, the antibody nirsevimab reduced the risk of a medically treated infection with the pathogen in infants by around 75 percent. The risk of hospital admission fell by 62 percent. In contrast to the drug Palivizumab – trade name Synagis – which has been approved for more than 20 years, the not yet approved Nirsevimab would not have to be administered monthly, but once before the start of the cold season.
RSV causes respiratory infections in both children and adults. The pathogen can cause bronchitis and pneumonia, especially in infants. Premature babies and children with previous illnesses, such as those affecting the lungs or heart, are particularly at risk. The monoclonal antibody palivizumab has only been approved for such risk groups for more than two decades. It cuts the risk of hospital admission by about half.
New RSV antibody with long residence time
The nirsevimab that has now been tested is also such an antibody, albeit with a longer residence time in the body. It binds to a protein of the virus and is intended to prevent its penetration into body cells. The effectiveness of this immunization was tested on 1500 healthy children aged up to 12 months who did not have any risk factors. More participants were originally planned, but the study overlapped with the beginning of the corona pandemic.
Almost 1,000 children were injected with the antibody, around 500 with a dummy preparation. In the drug-treated group, 1.2 percent of children developed an RSV infection that received medical treatment, compared to 5.0 percent of the unvaccinated. This corresponds to an effectiveness of 74.5 percent, writes the team to Tonya Villafana from the pharmaceutical company AstraZeneca in the “New England Journal of Medicine”.
Protection from hospitalization was 62 percent. 0.6 percent of those treated with the active ingredient and 1.6 percent of untreated children had to go to the hospital. The team calculates that almost 15 hospital admissions would be avoided for every 1,000 children who received the active ingredient.
Side effects were similar in both groups. Although three children died in the group treated with the drug, the researchers rule out a connection with prophylaxis.
RSV infection is only postponed
“The study addresses an important issue, 90 percent of all children go through an RSV infection in the first two years of life,” says the virologist Klaus Überla from the University Hospital Erlangen. “RSV infections are the most common respiratory infections leading to hospital admissions in young children.”
The fact that the active ingredient reduces the risk of being admitted to the hospital by more than 60 percent is an “impressive result,” says the virologist. “But we have to be aware that with this antibody therapy we are only postponing the infection.” Most children would then become infected at an older age. However, initial infections in older children were less severe – presumably because infants in particular are particularly sensitive to inflammation of their still very fine lung ducts.
However, important data were missing from the study, says Überla. There is hardly any information on the severity of the course of the disease in children who were hospitalized despite the administration of antibodies. Their absolute number – 6 in the prophylaxis group and 8 in the placebo group – is also too low. “More studies are needed on these questions.”
In terms of effectiveness, the study is convincing, says epidemiologist Rafael Mikolajczyk from the University Hospital Halle. The reduction in the risk of hospitalization shown could definitely be noticeable in clinics. However, effectiveness is not the only criterion. A decision on the regular use of the active substance requires a more comprehensive consideration.
(This article was first published on Sunday, March 06, 2022.)