COVID-19 Distribution Factors

Physical Processes: Viral Characteristics

• SARS-CoV-2 Genetic Makeup:
  • Novel coronavirus: The human body had no pre-existing immunity, leading to rapid spread.
  • Genetic differences: More efficient at attaching to and attacking human cells, causing them to replicate the virus.
    • Infects the entire respiratory tract (upper and lower).
    • More contagious, with a higher chance of spreading during the pre-symptomatic (incubation) period.
    • Greater coverage of infected cells in the respiratory tract (nose, throat, lungs) increases the probability of transmission.
    • More viral particles are shed during coughs or sneezes, facilitating rapid person-to-person and country-to-country spread.
  • This is associated with its spatial and temporal distribution based on its genetic composition.

Viral Variations and Adaptability

• Continuous Development of Variants:
  • SARS-CoV-2 continually develops variants.
  • Most variants do not significantly alter infection rates or symptoms.
  • Some variants are more contagious due to natural selection, influencing temporal and spatial distribution.
• Key Variants:
  • Alpha (B.1.1.7): Identified in September 2020.
    • 30-50% more contagious than the original SARS-CoV-2 virus.
    • More aggressive in attaching to and infecting human cells, leading to greater infection rates.
  • Beta (B.1.351): Identified in May 2020.
    • Has the ability to evade the immune system, even in vaccinated individuals.
  • Gamma (P.1): Identified in November 2020.
    • Exhibits ability to evade the immune system, even when vaccinated.
  • Delta (B.1.617.2): Identified in October 2020.
    • The most transmissible variant, approximately double that of the original strain.
    • Highly infectious due to increased virus replication in the airway systems.
    • Infectious for a longer duration and capable of evading certain antibodies.
    • Took approximately 10 months to spread to 100 countries.

Human Processes: Travel and Distribution

• Role of Travel:
  • Regional, national, and international travel significantly impacts the spatial distribution of COVID-19.
  • Movement of people and goods via planes and ships has aided in its global spread.
  • Returning overseas travelers have substantially contributed to the wide spatial distribution.
    • For instance, travelers returning from Italy and Iran were responsible for a significant proportion of the change in disease distribution in late February and early March 2020.

COVID-19 Reaction and Response

• Initial Global Response:
  • Most countries were unprepared to handle an infectious disease of such magnitude.
  • Some governments reacted slowly to the virus, delaying mitigation strategies or changes to daily behaviors.
  • Slow reactions allowed the virus to spread rapidly within countries and to other countries due to a lack of border controls and testing.
  • Governments attempted to balance economics with public health measures.
• Island Nations' Response:
  • Island nations had an advantage over landlocked countries in controlling the entry of COVID-19.
  • Greater control was achieved through border closures to prevent travelers from introducing the disease.
  • Island nations and territories were among the last places to report COVID-19 cases.