WILLEMSTAD – A preventive injection used in the Netherlands to protect babies against the respiratory syncytial virus (RSV) may be less effective in the Caribbean if administered according to the same schedule, according to new research conducted by the Radboud University Medical Center in collaboration with hospitals and laboratories in the Caribbean part of the Kingdom.
RSV is a common respiratory virus that typically circulates in the autumn and winter months in Europe. While most people experience only mild cold-like symptoms, the virus can be dangerous for infants. In severe cases, RSV can cause breathing difficulties, pneumonia and hospitalization, including admission to intensive care units.
In the Netherlands, a new preventive approach was introduced in late 2025 to protect infants. Instead of a traditional vaccine, babies receive antibodies that provide temporary protection against RSV for approximately six months. The measure has proven highly effective: the number of infants admitted to intensive care due to RSV infections has dropped by about 75 percent.
However, researchers found that the timing used in the Netherlands may not work as well in tropical regions.
Unlike Europe, the Caribbean does not experience autumn and winter seasons. Instead, the region has a dry season and a rainy season, which affects when viruses circulate. According to the study, RSV activity on Caribbean islands occurs mainly between June and December, during the rainy season.
This difference is significant because the antibody protection only lasts about half a year. If babies in the Caribbean receive the antibodies in September or October—following the same schedule used in the Netherlands—the protection may largely wear off by the time RSV activity rises again in June.
Researchers therefore recommend adjusting the timing of the injection for the Caribbean region. Administering the antibodies shortly before the start of the rainy season could provide more effective protection during the months when RSV is most active.
In the Caribbean Netherlands—Bonaire, Sint Eustatius and Saba—public health guidelines are managed by the National Institute for Public Health and the Environment. The institute is currently reviewing whether the timing of the preventive treatment should be adjusted.
Meanwhile, in Curaçao, Aruba and Sint Maarten, there is currently no standard RSV prevention program for infants. Researchers say they plan to continue working with local partners to determine how similar protective measures could be implemented on those islands.