The number of measles cases registered in the world in the first three months of 2019 triples. This is the alarm launched by Unicef against the figure of 110 thousand patients, 300% more than in the first quarter of 2018. A worrying figure that recalls the need for vaccination, a practice not always respected even in developed countries, the United States of America in the lead. We talk about it with Dr. Michele Lagioia, Head of the Medical and Health Directorate of Humanitas.

Measles: a health emergency

The first citizen of New York last April Bill de Blasio declared a state of health emergency throughout the city because of the measles epidemic spread in Brooklyn and ordered compulsory vaccination in the four areas most at risk in the neighborhood, with fines of up to a thousand dollars for those who do not comply. Just a week earlier, 80 new cases had been recorded, bringing the total in the city to 465, a record for the last 20 years. This is a direct consequence of a malpractice that sees the United States at the top of the list of high-income countries for the number of children (2.5 million) who have not received the first dose of measles vaccine between 2010 and 2017. In the unflattering ranking the USA is followed by France and the United Kingdom with over 600,000 and a half million children respectively not vaccinated in the same period. If on a global basis, in the same period of time, Unicef data speak of more than 21 million children a year without the first dose of vaccine, the latest available data on mortality and reported in 2017 records about 110 thousand deaths of measles, mostly children, 22% more than in 2016.

Italy is fifth for negligence

The ranking for unvaccinated children (2010-2017) sees Italy in fifth place with 435 thousand cases and it was from the summer of 2017, thanks to a specific decree law, that vaccination coverage began to rise for both the hexavalent and trivalent vaccine (measles-parotitis-rosolia). In particular, for the second, in less than a year, the coverage reached 93%. The high percentage must not, however, lead to lowering our guard; in fact, to keep cases of disease close to zero, coverage must be very high, otherwise there is the risk of witnessing the return of diseases such as measles, precisely, which had to be eradicated some time ago. In fact, in 2003 the National Plan for the elimination of measles and congenital rubella was approved in Italy in accordance with the World Health Organization’s instructions: the aim was to eradicate both diseases by 2015. The objective failed because in the first two months of 2017 692 cases of measles were reported, mainly in Piedmont, Lombardy, Lazio and Tuscany, equal to about all cases reported in 2016.

Safety threshold: 95%.

Vaccines work best when the coverage is high, because the basis of the success of vaccinations in preventing the spread of diseases is the concept of flock immunity. This term refers to the phenomenon that, once a sufficient level of vaccination coverage is reached within the population, unvaccinated persons can also be considered safe. Being surrounded by vaccinated individuals, and therefore unable to transmit the disease, is crucial to stop the spread of an infectious disease. The minimum threshold varies according to the infection because the various pathogens (viruses and bacteria that can trigger the disease) have different rates of infectivity. In general, 95% is considered to be the minimum level to ensure that this phenomenon occurs.