Carlos SolisA new study from the University of Pittsburgh (USA) has revealed that widespread vaccination against protects both vaccinated and unvaccinated individuals from infection. However, the greatest protection is still afforded to those who have received the vaccine.
Researchers conducted computer modeling involving 1.2 million people in one of the U.S. counties. The model tracked the daily spread of influenza within families, schools, workplaces, and residential areas.
The modeling aimed to assess the effectiveness of a vaccine with a 40% efficacy across different flu seasons, varying rates of virus transmission, and different levels of vaccination coverage. Each simulated scenario was run 100 times, and the researchers calculated average values based on the data obtained.
What Did the Modeling Reveal?
When vaccination coverage reached 51% of the population, the overall number of flu cases decreased by 32.9% to 41.5%, depending on the severity of the illness. The positive effect was observed in both vaccinated and unvaccinated individuals (to a lesser extent).
“Vaccination against strains of the similar to those circulating during the seasonal flu provided indirect benefits to the unvaccinated, but the direct benefits for the vaccinated were always greater,” the researchers noted in their report.
In other words, by getting vaccinated, you not only significantly increase your chances of avoiding infection but also protect others, even if they have not been vaccinated.
This is not just about anti-vaxxers who are staunchly opposed to vaccination. This finding is particularly significant for those who cannot receive vaccinations for medical reasons.
Thus, the study confirmed that the more people who are vaccinated, the fewer overall cases of infection there will be. Both vaccinated and unvaccinated individuals experience less contact with sick people, as reported by Science Alert.
However, scientists believe that this remarkable effect should not serve as an excuse for those who are eligible for vaccination to avoid getting vaccinated.
During the modeling, the likelihood of contracting influenza for unvaccinated individuals was still 43% to 73% higher, depending on the vaccine’s effectiveness. Moreover, the protection for unvaccinated individuals was nearly nullified when the virus spread too rapidly, as was the case during the early stages of the pandemic. Therefore, directly vaccinating as many people as possible remains crucial.
“When vaccine efficacy and coverage levels were low, vaccination showed a noticeable reduction in illness at transmission levels typical of seasonal flu. However, when transmission rates were very high, even an effective vaccine did not protect unvaccinated individuals,” the team stated.
The data also demonstrated certain limitations of herd immunity. When a population develops sufficient resistance to infection through natural immunity or vaccination, the spread of infection is limited, helping to protect unvaccinated individuals. However, this indirect vaccination does not adequately shield the body from pathogens that spread very quickly.
The study’s results were published in the journal JAMA Network Open.
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