[Determination of complement-fixing antibodies to respiratory syncytial virus. Longitudinal study in a population of less than 1 year of age in the City of Havana].

Respiratory syncytial viruses (RSV) are considered among the most important agents causing acute respiratory infections in infants below 1 year of age. A 10-year longitudinal study of monosera from children under 15 years was carried out; 1,069 monosera from children under 1 year were studied using the RSV antigen complement-fixing technique. It was observed that there were short or longer periods between the peaks of positive sera and when they were compared with medical care reports, they showed correspondence with increased numbers of medical care reports. A typical seasonal pattern in the distribution of antibodies was determined and this corresponded to the month of February, suggesting that this is probably due to the circulation of the virus and not to maternal antibodies. The results attained give grounds for considering the possible circulation of RSV in our country.