COVID VACCINE: Why regular vaccination updates will be necessary

Since the introduction of COVID-19 vaccines, there is great uncertainty about the duration of vaccine immunity and the appropriate time frame for a new booster injection. Many studies have estimated the term of protection Just a few months away, this team of scientists from the Yale School of Public Health and the University of North Carolina confirm:

strong protection after vaccination is short-lived.

The study is the first to estimate the probability of future infection from natural infection after vaccination with one of the currently available vaccines. The researchers developed a model of infection risks, fed by infection data over time and inspired by previous coronavirus reinfection models. These similarities have allowed scientists to make longer-term projections than studies focused only on current infections. In addition, the model took into account the differences in antibody responses related to natural immunity and vaccine immunity, which allowed comparison between the different scenarios.

  • The risk of so-called “breakthrough” infection (or breakthrough infection), that is, after vaccination, depends on the type of vaccine.

What is the best protection? According to the study, current mRNA vaccines (Pfizer, Moderna) provide the longest-lasting protection, almost 3 times longer than natural infection and other vaccines (Johnson & Johnson and Oxford-AstraZeneca). “mRNA vaccines produce the highest levels of antibody response and, in our analysis, confer longer-lasting protection than other vaccines or exposures,” said lead author Jeffrey Townsend, professor of biostatistics at Yale. . Specifically, the researchers estimated infection risk trajectories, and thus mean times to onset of advanced infection, for each vaccine under endemic conditions.

  • Antibody levels elicited by messenger RNA (mRNA) vaccines exceed those induced by natural infection and generally provide longer-lasting protection against breakthrough infections (median 29.6 months, 10.9 months to 7 months). ,9 years);
  • against natural infection (median 21.5 months, 3.5 months to 7.1 years);
  • the other vaccines provide antibody responses similar to those of natural infection and thus provide weaker and shorter-term protection against breakthrough infections (median 22.4 months, 4.3 months to 7.2 months). years);
  • Therefore, booster vaccination might, in some individuals, only provide protection for a few months against a new infection.

Natural and vaccine immunity are not mutually exclusive: Many people derive their immunity from more than one source, so understanding the relative effect of each type of exposure on our immune systems is essential. This study confirms that reliable protection against reinfection requires adequate booster vaccines to deal with the natural and permanent evolution of the virus.

“It’s an arms race with this virus,”

that could develop ways to evade both our natural immune response and any vaccine-derived immune response. As we saw with the Omicron variant, vaccines against early strains of the virus become less effective at fighting new strains of the virus.”

However, scientists are reassuring in confirming that SARS-CoV-2 mirrors other endemic coronaviruses that evolve and reinfect us despite our natural immunity linked to earlier strains.

Therefore, the update of the vaccines seems essential to counteract the resumption of the pandemic.

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