Immunological characteristics govern the transition of COVID-19 to endemicity
science.sciencemag.org
One year after its emergence, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become so widespread that there is little hope of elimination. There are, however, several other human coronaviruses that are endemic and cause multiple reinfections that engender sufficient immunity to protect against severe adult disease. By making assumptions about acquired immunity from its already endemic relatives, Lavine et al. developed a model with which to analyze the trajectory of SARS-CoV-2 into endemicity. The model accounts for SARS-CoV-2's age-structured disease profile and assesses the impact of vaccination. The transition from epidemic to endemic dynamics is associated with a shift in the age distribution of primary infections to younger age groups, which in turn depends on how fast the virus spreads. Longer-lasting sterilizing immunity will slow the transition to endemicity. Depending on the type of immune response it engenders, a vaccine could accelerate establishment of a state of mild disease endemicity. Science , this issue p. [741][1] We are currently faced with the question of how the severity of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may change in the years ahead. Our analysis of immunological and epidemiological data on endemic human coronaviruses (HCoVs) shows that infection-blocking immunity wanes rapidly but that disease-reducing immunity is long-lived. Our model, incorporating these components of immunity, recapitulates both the current severity of SARS-CoV-2 infection and the benign nature of HCoVs, suggesting that once the endemic phase is reached and primary exposure is in childhood, SARS-CoV-2 may be no more virulent than the common cold. We predict a different outcome for an emergent coronavirus that causes severe disease in children. These results reinforce the importance of behavioral containment during pandemic vaccine rollout, while prompting us to evaluate scenarios for continuing vaccination in the endemic phase. [1]: /lookup/doi/10.1126/science.abe6522

“The model code provides a flexible scaffolding for studying alternative vaccination scenarios. Notably, the model predicts that once the endemic state is reached, mass vaccination may no longer be necessary to save lives.”

“Should the vaccine cause a major reduction in transmission, it might be important to consider strategies that target delivery to older individuals for whom infection can cause higher morbidity and mortality, while allowing natural immunity and transmission to be maintained in younger individuals.”

“Additionally, during the transition to endemicity, we need to consider how the immune efficacies depend on primary and secondary infections across ages and how responses differ between vaccination and natural infection.”

“The key result from our model framework that explicitly recognizes that functional immunity to reinfection, disease, and shedding are different is that, in contrast with infections that are severe in childhood, SARS-CoV-2 could join the ranks of mild, cold-causing endemic HCoVs in the long run.”

“The transition from epidemic to endemic dynamics is associated with a shift in the age distribution of primary infections to lower age groups. This transition may take anywhere from a few years to a few decades, depending on how quickly the pathogen spreads. The rate of spread, measured by R0, is determined by a combination of viral properties and the frequency of social contacts and may therefore be reduced by social distancing.”

  • Axaoe
    4·
    4 years ago

    I disagree with your title, and wish you would have used that of the article/paper (possibly generating more discussion in the process).

    I mainly disagree because it feels like an over simplifaction of the issue based on long term results, see in this section (which you quoted part of above):

    Slowing down the epidemic through social distancing measures that reduce R0 to close to 1 flattens the curve, thus delaying infections and preventing most deaths from happening early on, affording critical time for the development of an effective vaccine (fig. S10). If vaccine-induced IES and IEP immunity is similar to that induced by HCoV infections, the vaccine may usher in the endemic regime more quickly. The model code (see the acknowledgments) provides a flexible scaffolding for studying alternative vaccination scenarios. Notably, the model predicts that once the endemic state is reached, mass vaccination may no longer be necessary to save lives (see SM section 4 and fig. S11).

    I still enjoyed the link however, thanks for sharing it!

    • disrooterOP
      4·
      4 years ago

      Yes the title is an over-simplification but the original title was too technical for general audience.

      Basically the article want to provide an analysis of the possible scenarios removing the assumpion that the immunity induced by the vaccine is the same of one induced by infections and the result is social distancing may be counterproductive.

      The point is, one shouldn’t argue for keeping social distancing or even lockdowns once vaccines are available for better securiry because it can be counterproductive.