Filenews 24 August 2021
As the population's vaccination against SARS-CoV-2 progresses, questions arise as to whether this pandemic will end with the building of the "wall of immunity"."
The boundary of the wall of immunity was placed on achieving immunity in 60-70% of the population either through disease or through vaccination. This goal as we are in the second year of the pandemic seems intractable, due to new strains, scepticism towards vaccination, and delayed vaccination of children.
The Doctors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens Theodora Psaltopoulou, Panos Malandrakis, Giannis Danasis, and Thanos Dimopoulos (Rector of the University of Athens) summarize the relevant publication of Nature.
The fact that the wall of immunity is an intractable scenario now does not diminish the value of vaccination as a weapon in the face of the pandemic. In the near future, scientists now believe that a return to normality does not require a wall of immunity, but in the long run COVID-19 infection will be endemic in nature.
This reasoning is based on a number of reasons such as:
1. It is unclear whether and to what extent vaccines protect against the transmission of the virus.
The key to the wall of immunity is that if someone is ill, there are few people who are infected (who may become infected) people in his environment. Vaccines have proven their effectiveness against symptomatic disease, but the data around preventing transmission is not yet mature, and this is a focal point in helping vaccination to the wall of immunity. No 100% protection against transmission is required, and a 70% protection rate of the vaccine from transmission of the virus would be sufficient.
2. The sharing of vaccines is unequal.
A coordinated simultaneous global vaccination mobilization could theoretically eliminate COVID-19 infection. However, different vaccination coverage across countries, or even within states in the same country (U.S.), and different age groups vaccinated per specific period, with children not yet vaccinated, can lead to new outbreaks even in countries with vaccination rates that touch the wall of immunity. If we assume that most minors are not vaccinated (since vaccines for ages under 16 have not yet been approved), then 100% of the population over 18 years of age must be vaccinated, in order to reach 76% immunity in the entire population.
3. New strains upset the balance of the wall of immunity.
The example of Brazil explains this case. Due to the massive outbreaks at the beginning of the pandemic by June 2020, it was estimated that more than 60% of the population became ill, a figure that the wall of immunity could achieve. However, in January 2021, the new strain, also known as P.1, led to a new outbreak. Rapid mass vaccination could prevent new strains from appearing, and dominating.
4. Immunity may not last forever.
Its wall of immunity is achieved either through vaccination or through natural infection. The length of time, which lasts the immunity provided by the natural infection is not known. The data so far from previous coronaviruses show that immunity is gradually decreasing, not reaching zero but not forever at 100%. Also, vaccines are not 100% effective. If we assume that natural immunity lasts only a few months then the time limits for the implementation of vaccination are even narrower. It is also necessary to determine the duration of the immunity provided by vaccines, and when and if doses of reinforcement will be needed.
5. The completion of vaccination changes human behaviour.
As people are vaccinated they gradually relax prevention measures, increase their interactions, and tip the scales of the wall of immunity, which also depends on the person's exposure to the virus. Vaccines have an efficacy of up to 90%, so if before the vaccine someone came into contact with one person, and then comes into contact with 10, then he ends up in the same place. The use of masks will contribute to the interruption of the chain of transmission, preventing the prevalence of new strains until vaccination is completed. People very quickly want to return to their lives and behaviour before the pandemic, however it is important to make it clear that we are not yet safe from the pandemic, but we are "safer than we were"."
Based on the evidence so far, vaccination may realistically not provide us with the wall of immunity and not be able to put an immediate end to COVID-19 infection, but it can reduce hospitalizations and mortality of infection especially in vulnerable groups. The infection may not disappear immediately, but its severity and threat will fade.
