a new control system in the face of the lack of coverage?

“Millions of people are still without immunization coverage” around the world, alert the World Health Organization. However, an unvaccinated person is vulnerable to life-threatening illnesses. Ultimately, this can lead to “the re-emergence of previously controlled diseases, the spread of diseases in countries where they had been eliminated and the heavy cost that millions will continue to pay,” writes the WHO.

Also, to better monitor the vaccination of people living in developing countries, where paper vaccination cards are often incorrect or incomplete and electronic medical records nonexistent, researchers from MIT have developed a system based on nanoparticles injectable under the skin. Thanks to a smartphone, a doctor will be able to check whether the person has been vaccinated or not. This technique, tested only on rats at the present time, was described Wednesday December 18 in the review Science Translational Medicine.

The researchers created copper-based nanocrystals, called quantum dots, 3.7 nanometers in diameter and encapsulated in microparticles of 16 micrometers (1 micrometer is one millionth of a meter and 1 nanometer is one billionth) . The whole is injected by a patch of micro-needles 1.5 millimeters in length.

Small dots visible thanks to a modified smartphone

Scientists tested this system on rats. After being applied to the skin for two minutes, the micro needles dissolve and leave small dots under the skin, forming a circle or a cross. If these dots are invisible to the human eye, a modified smartphone, pointed at the skin, allows them to appear on the screen. These small dots would be injected at the same time as the vaccine. So, years later, a doctor could point their smartphone at someone and check if the patient has been vaccinated against a particular disease.

If researchers hope to be able to test their method within the next two years, it will only be useful if it becomes exclusive. Furthermore, there is no evidence that people will agree to be labeled under the skin for each vaccine. Finally, concerning children, what will happen to the points when they grow up? To find out more, the Bill Gates Foundation, which is funding this work, is conducting public opinion surveys in Kenya, Malawi and Bangladesh.

The eternal fear of the vaccine

However, some people may refuse vaccines. Michel Zaffran, director of the polio eradication program at WHO, says that, like some Westerners, some people in developing countries believe rumors that vaccines are making people sick or intended to be sterilized children, even women. Governments do not help by mobilizing sufficient human and financial resources. Even more complicated than according to UNICEF, 29% of children are not registered at birth, which automatically excludes them from official registers.

“This reflects a lack of prioritization on the part of governments to make vaccination a national and public good”, denounces Michel Zaffran.

In July, WHO and UNICEF presented a disturbing report on immunization coverage worldwide. According to their findings, in 2018, almost 20 million children did not receive vaccines that could prevent fatal diseases, most of them living in poor or conflict-affected countries. “If these children fall ill, they are at risk of serious complications, and are less likely to have access to treatment and care that would save them,” said the WHO.