Viruses have mutated and countries are sharing data to help control the spread of infection. For ease of communication, when variants are discovered, they are given a unique label. The Pango lineages of different variants may overlap. The points of mutations in the genes for each variant are also recorded. Several variants have common mutation points, and it is useful to the scientific communities to know the variants that are similar to others.

A variant is given a classification when it becomes necessary, and the classifications are based on factors such as speed of transmission and the number of cases. The categories are as follows: variant being monitored, a variant of interest, a variant of concern, and the variant of high consequence.

When a country detects case(s) of the variant, the date(s) and patient biodata, identified by a running case number for that country are tracked. Patient biodata includes data such as nationality, gender, year of birth, vaccination history, as well as patient symptoms. Each symptom has a general description. For example, a low-grade fever is described as any temperature 99.5°F (37.5°C) and 100.3°F (38.3°C). The scientific communities note that there are cases of reinfection, possibly from the same or different variants, and these cases are of special interest.

For each country, record the population size as well as the percentage of the population that has been vaccinated. Cases are also defined as local primary, local secondary, or imported cases. Imported cases have a history of travel from an affected county 14 days before the onset of infection. The travel history of such cases must be recorded.

Construct a conceptual model from the statements of requirements to represent the data model, showing

• Entities, with entities named, relevant attributes, and identifier,
• Relationships with maximum and minimum cardinalities and relationship names.