Scientists said that the protection provided by vaccines to prevent the Corona virus and its development of dangerous symptoms is very likely that it will decline over time, while a new study warns against the hasty easing of restrictions imposed to confront the pandemic.

A summary of a document prepared by a group of scientists within the advice of the British government showed that "it is very likely that the immunity induced by vaccines, protecting against infection (SARS-Cove-2) and from developing severe symptoms due to it will decline over time", but to a lesser extent in relation to the severity of symptoms.

The scientists added, "Therefore, it is also likely that vaccination campaigns to prevent (SARS-Cove-2) will continue for the coming years, but currently we do not know what the optimal frequency of revaccination is required to protect those most at risk from Covid disease."

The document, excerpted by Reuters, is titled “How long can Covid-19 vaccines continue to be administered?” and was written by a team of eminent virologists and epidemiologists from Imperial College London, University of Birmingham and Public Health Service England.

easing restrictions

On the other hand, a study published today, Friday, showed that easing health restrictions, such as not imposing the muzzle and adherence to physical distancing at a time when not all the inhabitants of the planet have been immunized yet, greatly increases the risk of the emergence of more resistant mutations to the anti-Coronavirus vaccines.

While nearly 60% of Europeans have received at least one dose of the COVID-19 vaccine, this study shows the need to maintain other measures in addition to the vaccine until everyone is vaccinated, its authors explained.

In order to study how the Corona virus can mutate in response to increased vaccination campaigns, a team of researchers from several European countries simulated the possibility of a vaccine-resistant strain emerging in a population of 10 million people within 3 years.

The model that they developed included variables, including the population vaccination rate, the rate of virus mutation and the speed of its transmission, and the expectation of successive “waves” with an increase in the number of infections followed by a decrease in new infections after the introduction of restrictions.

The study, which was quoted by the French press agency "Nature Scientific Reports", concluded that rapid vaccination reduces the risk of the emergence of a resistant strain.

selection pressure

But the model adopted in the study also shows that the risk of developing a resistant strain is maximum when a large part of the population is vaccinated, but not enough to ensure herd immunity.

This phenomenon has been dubbed "selection pressure" by researchers, and as more of the population develops antibodies to the virus, the more resistant strains will have a competitive advantage.

According to the researchers, the probability of the emergence of more resistant mutant becomes higher when more than 60% of the population is vaccinated.

This is consistent with the current epidemiological situation in most European countries, which are witnessing a rapid spread of the delta axis.

These results show the need to maintain precautionary measures so that everyone is immunized and to make a "real global vaccination effort", otherwise "it will be possible to eradicate vaccine-resistant strains in some areas, but they will persist in other places" before spreading again, the researchers emphasized.