In order to protect yourself from the risks of Covid, it is sufficient to vaccinate more than half of the population. This is because when a sufficient proportion of the population is immune to infectious diseases (through vaccination or natural infection), human-to-human transmission is impossible.
The higher the percentage of immunized people in the community, the less likely the non-immune people will come into contact with infected people.This is the concept behind the so-called indirect form of protection Herd immunityIn this case, a sufficient percentage of the population is immune to infectious diseases (through vaccination and/or natural infection), so it is difficult to spread from person to person.
Herd immunity in the community
Therefore, this phenomenon reduces the risk of susceptible people coming into contact with pathogens, and its realization depends on the level of immunity acquired by the community.For the Sars-Cov-2 coronavirus, the lowest threshold assumed by the World Health Organization (WHO) is 60-70% of the population vaccinated, which is the percentage of Italy Reachable in summer In countries like the United Kingdom, more than 30 million people have received at least one dose of Covid vaccine, and at least 4 million people have survived the infection. Its total population is approximately 68 million. It is estimated that University College London ( UCL) is only one step away from now.
The scientist’s prediction ischain reaction -Comment on UCL Professor Carl Friston-. If you eliminate the chance of the virus spreading, it will dieScientists at Imperial College London have a different view. Among other factors, considering that only slightly more than 7 million people have also received the second dose of the vaccine, it is calculated that no more than 44% of the countries are considered to be affected. Protection from viruses.
It is not simple to calculate the number required to obtain the immunity of the herd, but only through vaccination to estimate the immunity rate required to achieve the immunity of the herd A mathematical formula The basic copy number (R0) is considered, which represents the average number of cases in a positive population that is completely infected.The formula used to calculate the minimum critical percentage (Vc) to be inoculated is equal to 1-1 / R0 (R0 minus 1), So the higher the R0 of a given pathogen, the higher the percentage of people who need to be immunized.
Covid risk protection
As we have explained here, the coverage rate of vaccinations to achieve immunization against Sars-Cov-2 coronavirus in the herd is estimated to be 60-70%, which is precisely based on the following assumption: the average R0 of the infectious disease vector The value is equal to 3 (1-1 / 3 = 2/3, or 66%).When calculating with these terms, it is assumed that the population is completely susceptible to the virus, and this situation obviously does not take into accountThe evolution of the pandemicTherefore, the number of infected people who have developed antibodies and the potential transmission capacity of new variants recognize that current vaccines are equally effective. Therefore, the uncertainty of certain factors, including the duration of immunity, makes mathematical calculations complicated rather than exhaustive.
On the other hand, achievement The vaccination rate reaches 60% Of course, this percentage is sufficient to protect people from the risk of Covid (considering the ongoing vaccination campaign, which aims to provide vaccination to the age group most vulnerable to severe diseases and vulnerabilities), and an important part of the strategy Under arrest or Slow the spread of disease. As mentioned earlier, in addition to those who have been infected, being surrounded by a high proportion of vaccinated people reduces the possibility of infection for people who still lack immunity or cannot be vaccinated due to diseases. Another very important part of the struggle is monoclonal antibodies, which, if used properly, can avoid hospitalization and treatment in the intensive care unit. In addition to these, there may soon be drugs that can block viral replication and pro-inflammatory cytokines. Together, all interventions will allow us to reach the light at the end of the tunnel.