Palivizumab vaccine for prevention of respiratory syncytial virus infection in children with cystic fibrosis

Review question

We reviewed the evidence about the effects of vaccinating children with cystic fibrosis with palivizumab to prevent respiratory syncytial virus.

Background

Respiratory syncytial virus commonly causes lung infections in infants and children. Although cases are not severe in most children, children with cystic fibrosis may be at higher risk for severe lung infections from the virus. During a respiratory virus season, children with cystic fibrosis are more likely to need admitting to hospital and to experience a deterioration in lung function, compared with children who don't have cystic fibrosis. Palivizumab (Synagis®) is a vaccine which has been shown to reduce hospitalisation rates due to respiratory syncytial virus in some high risk populations. Palivizumab is administered once a month for five months, beginning before the respiratory syncytial virus season each year. It is not yet known how effective and safe this vaccine is in children with cystic fibrosis. We looked for randomised controlled trials (trials where children are put into different treatment groups at random and then compared to each other) where palivizumab vaccinations were compared to either another preventive therapy or no preventive therapy in children with cystic fibrosis.

Search date

The evidence is current to: 05 May 2016.

Study characteristics

We found one study with 186 participants (infants with cystic fibrosis up to two years of age) which was run across 40 centres in the USA.

Key results

One infant (out of 92) who received palivizumab and one infant (out of 94) who received placebo were admitted to hospital due to infection from respiratory syncytial virus. No infants died. Overall, the number of adverse events in the palivizumab group was similar to that in the placebo group. No serious adverse events were reported to be related to the vaccine. Over the longer term (12 months), weight gain and the number of infections with Pseudomonas aeruginosa (a common bacterial infection in cystic fibrosis) were similar between groups.

The limitation of all these findings is that we only identified one study. More research is needed on the use of the palivizumab vaccination in children with cystic fibrosis.

Quality of the evidence

We thought there was a low risk that it would be know which treatment group the next participant would be put into, although it was not clear how this order was generated. We also thought that participants and study personnel were sufficiently blinded to the treatment to avoid bias and that any missing data were unlikely to bias the study results. However, we did have concerns about bias from selective reporting (summary statements were presented but without any data) and the fact that this industry-supported study has not been published as a full report in a peer-reviewed journal.

Authors' conclusions: 

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with cystic fibrosis. While the overall incidence of adverse events was similar in both groups, it is not possible to draw firm conclusions on the safety and tolerability of respiratory syncytial virus prophylaxis with palivizumab in infants with cystic fibrosis. Six months after treatment, the authors reported no clinically meaningful differences in outcomes. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with cystic fibrosis.

Read the full abstract...
Background: 

Respiratory syncytial virus infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe respiratory syncytial virus infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing respiratory syncytial virus hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent respiratory syncytial virus hospitalisations and intensive care unit admissions in children with cystic fibrosis. This is an update of a previously published review.

Objectives: 

To determine the efficacy and safety of palivizumab (Synagis®) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from respiratory syncytial virus infection in children with cystic fibrosis.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.

Date of last search: 05 May 2016.

Selection criteria: 

Randomised and quasi-randomised studies.

Data collection and analysis: 

The authors independently extracted data and assessed risk of bias.

Main results: 

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N = 92) to placebo (N = 94) over one respiratory syncytial virus season was identified and met our inclusion criteria. We judged there to be a low risk of bias with respect to the concealment of the randomization schedule (although it was not clear how this was generated) and to blinding of participants and study personnel. There is also a low risk of bias with regards to incomplete outcome data. However, we judged there to be a high risk of bias from selective reporting (summary statements presented but no data) and the fact that this industry-supported study has not been published as a full report in a peer-reviewed journal.

At six months follow-up, one participant in each group was hospitalised due to respiratory syncytial virus; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while five and four children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

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