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The following is a summary of “RSV Neutralizing Antibodies Following Nirsevimab and Palivizumab Dosing,” published in the October 2024 issue of Pediatrics by Wilkins et al.
Nirsevimab, a new monoclonal antibody with an extended half-life, has been shown to provide sustained protection against respiratory syncytial virus (RSV) compared with palivizumab, the previous standard of care.
Researchers conducted a prospective study to compare RSV-neutralizing antibody (nAb) levels following administration of nirsevimab and palivizumab.
They analyzed the MEDLEY study (phase 2/3, randomized, palivizumab-controlled) and assessed RSV-nAb levels, nirsevimab, and palivizumab concentrations in infants born preterm (≤35 weeks gestational age) or with congenital heart disease (CHD) or chronic lung disease (CLD) of prematurity, over 2 RSV seasons. Participants received either 1 dose of nirsevimab or 5 monthly doses of palivizumab. Blood samples were collected at baseline and on days 31, 151, and 361 to analyze serum concentrations and antibody levels.
The results showed that nirsevimab predominantly conferred pre-fusion (pre-F) antibodies, whereas palivizumab conferred both pre-F and post-fusion (post-F) antibodies. Nirsevimab and palivizumab serum concentrations strongly correlated with nAb levels. In season 1, nAb levels in recipients of nirsevimab were highest at day 31, then declined but remained 17-fold higher than baseline at day 361, nAb levels in recipients of palivizumab increased incrementally through monthly doses to day 151. Additionally, nAb levels were about 10 times higher in recipients of nirsevimab than in recipients of palivizumab in both seasons.
They concluded that nirsevimab provided significantly higher and more sustained RSV-nAb levels compared with palivizumab.
