[Measles]

In April 2019, UNICEF denounced that more than 20 million children worldwide had not been vaccinated and alerted on possible outbreaks of measles which, due to the high transmissibility of this virus, is the first disease preventable by vaccination to emerge. If the decline in vaccinations continues, pertussis, tetanus and other diseases, which require less coverage to achieve population protection, may also reappear. In Argentina, the current outbreak began in late August 2019. Measles virus is transmitted by air, infects multiple organs, and is associated with immunosuppression. Its genome consists of single stranded RNA. Genotyping is carried out by sequencing a 450-nucleotide fragment of the N protein, which contains the highest density of nucleotide variation. In South America, D8 is the circulating genotype and in North America, B3 accounts for 8% of the cases. Each person with measles infects, on average, another 12-18 people in a susceptible population. Vaccination confers direct and indirect protection, and induces both antibodies and cellular immunity. Newborns are protected by maternal antibodies transmitted via the placenta, up to 6 months. In Argentina, the Vaccination Calendar includes two doses of triple viral vaccine, at 12 months and 5 years, and a zero dose (6-11 months of age) in districts with disease cases. The protection conferred by the vaccine is 93% at 12 months with a dose, and with 2 doses 97% for life.