In discussions about additional vaccination against COVID-19, two aspects inevitably arise: personal (how much will I be protected) and public (whether it will be possible to form herd immunity, which protects, including those who, for whatever reason, cannot be vaccinated, and prevents the spread virus).
In this pandemic, the public is suddenly terribly disappointed that anti-coronavirus vaccines do not protect against infection. The belief that a person will never develop symptoms after being immunized comes from experience with childhood vaccines such as measles, polio or mumps. But, strictly speaking, we do not know for sure whether they guarantee one hundred percent sterilizing immunity: there are almost no pathogens causing these diseases in Western countries, so the chance of a vaccinated person to meet and test protection is small. And even if a meeting takes place, we do not know exactly what events unfold in the body of the vaccinated. It may well be that the virus enters the cells sensitive to it and begins to multiply, but the immune system trained by the vaccine very quickly notices the invasion and destroys the enemy. As a result, the likelihood of developing symptoms depends both on the vaccine and on the properties of the pathogen and the characteristics of its interaction with the immune system: some viruses can manifest themselves already in the early stages of infection, others need to roam properly so that the infected person feels that something is not OK.
But in terms of personal safety, it doesn’t matter whether you get infected or not. It matters whether the symptoms are so severe that you end up in the hospital, end up in the intensive care unit on ventilators, or die. A positive test by itself, as well as a cough, fever, or short-term loss of taste (although this symptom is much less common in the delta strain, unlike its predecessors), do not indicate that the vaccine is ineffective. A slight discomfort can be unpleasant, but it does not seriously threaten your health – you are not afraid of common colds, are you? And the statistics from different countries testifythat in many regions with a high percentage of vaccinated, even with relatively large numbers of new infections, the percentage of hospitalizations and deaths does not increase.
In other words, with this understanding of effectiveness, one course of existing vaccinations at the moment looks quite sufficient. One of the illustrative illustrations of this thesis is Work, the authors of which studied an outbreak of delta-induced covid in a Texas federal prison. From the very beginning of the pandemic, penitentiary institutions in America have competed with nursing homes in terms of the number of infections and deaths: both there people live crowded, plus, many have risk factors for developing a severe form of the disease. After the anti-coronavirus vaccines were developed, the American prison population was largely vaccinated. In the prison referred to in the study, 79% of inmates were fully immunized. In early July, an outbreak of covid began in the prison, and the virus was eventually detected in 172 out of 233 prisoners (79%). Among the vaccinated, 70% were infected, among the unvaccinated – 93%. Four were hospitalized, three of whom were not vaccinated. One of the unvaccinated hospitalized died. Of course, a prison is an artificial situation, and in ordinary life people do not communicate with a large number of the same people so closely and for a long time. However, this spontaneously organized experiment shows that although vaccinated people can become infected, vaccines reliably protect them from severe disease.