Measles, might the vaccine not cover a variant of the virus? The answers from the Istituto Superiore di Sanità

Measles, might the vaccine not cover a variant of the virus?  The answers from the Istituto Superiore di Sanità


OfMaria Giovanna Faiella

Infections are increasing in Italy: 64 cases of measles in the first two months of this year. Vaccination coverage below 95%, the safety threshold recommended by the WHO. The new variant: is there anything to worry about?

Lately a study conducted by the University of Milan and the Higher Institute of Health, published on Eurosurveillanceone revealed new variant of measles (we talked about it here) «in which some mutations are found that give a slight loss of sensitivity to one of the molecular tests in useeven if different from the one most used in our country.”
Is there anything to worry about? The Istituto Superiore di Sanità itself, which publishes on its own, provides clarity site questions and answers about «Measles and variants, what to know».

What is measles and how can it be prevented

The measles it is a very contagious infectious disease caused by a virus that is transmitted by air and causes high fever, pharyngitis, conjunctivitis and a characteristic skin rash (exanthema). It can become dangerous as it can cause serious complications, which are relatively rare, mainly due to bacterial superinfections: otitis media, laryngitis, diarrhea, pneumonia or encephalitis (inflammations of the brain), up to the most insidious encephalitisThat can cause permanent damage such as mental retardation, epilepsy, deafness and in some cases be fatal.
Measles can be prevented with vaccination, offered free of charge to all children by the National Health Service: it can be administered by quadrivalent combined MPRV vaccine (measles-mumps-rubella, chickenpox) or via trivalent MMR vaccine (measles, mumps, rubella). There first dose it is administered in the second year of life; The recall at 5-6 years.

Vaccination coverage less than 95%

In our country coverage is less than 95 percentwhich is the safety threshold recommended by the World Health Organization to guarantee theimmunity «of flock» in the population, that is to protect indirectly even those who, for health reasons, cannot be vaccinated.
In 2022, as reported by the Higher Institute of Health in the published note, vaccination coverage for measles «came to 92% of the population for the first dose and to the86% for the second dosedown 1% and 3% respectively compared to 2018. However, 2022 data reports 94.4% coverage in children under 24 monthsvery close to 95% and certainly higher than the 86% of 2016, the year that preceded the 2017 epidemic.”

Pwhy is there so much talk about measles?

As the Institute’s experts report, in 2023 there was a sharp increase measles cases across Europereported by the World Health Organization: last year, in fact, on the European continent have been registered 21 thousand hospitalizations and 5 deaths.
In Italy the surveillance system, coordinated by the Infectious Diseases Department of the ISS, recorded 43 cases of measles, a clear increase compared to 15 in 2022. A growing trend, given that, as reported by the Istituto Superiore di Sanità, in January 2024 have been reported 29 cases of measles and on February 35in total 64 in the first two months30%-40% imported.

The variant that escapes testing

Compared to the measles variant found in Italy, the ISS specifies that «this result suggests continuing to be maintained the attention threshold is high to verify thepossible need to update molecular tests». However, experts point out that “molecular tests are not the only types of tests in use to confirm a measles diagnosis. The main tests for confirming the diagnosis are in fact: serological testsin particular the measurement of specific IgM.”

Could the variant also “escape” the vaccine?

As for the possibility that the new variant escapes the vaccine, the ISS reassures: «It can be excluded that the mutations described could influence the efficacy of the vaccine. The measles virus is a very stable virus and for over 60 years vaccination has provided effective protection against all circulating genotypes. The natural evolution of the virus into a strain that escapes the vaccine is a highly unlikely event» conclude the experts.

March 1, 2024

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