Let's talk infectious diseases, the reason for vaccines: ⱽᵃʳⁱᵃⁿᵗˢ

So, let's talk variants. It's a hot topic these days with numerous variants of the COVID-19 virus evolving. Viruses are changing and mutating all the time. It happens when the virus enters our body and makes copies of itself as it spreads from cell to cell. Sometimes the virus makes a mistake and its genetic information is changed slightly as it’s copied. Sometimes those errors cause a disease to fade away; other times, it causes the virus to become more deadly or easily spread.

First, a vocab lesson:

• Mutation:  A mutation refers to a single change in a virus’s genome (genetic code). Mutations happen very frequently, but only sometimes change the characteristics of the virus.
• Lineage: A lineage is a group of closely related viruses with a common ancestor. SARS-CoV-2 has many lineages; all cause COVID-19.
• Variant: A variant is a viral genome (genetic code) that may contain one or more mutations. In some cases, a group of variants with similar genetic changes, such as a lineage or group of lineages, may be designated by public health organizations as a Variant of Concern or a Variant of Interest due to shared attributes and characteristics that may require public health action.

When a variant is suspected it is elevated to being studied in depth. If it is considered to have concerning epidemiological, immunological or pathogenic properties, they graduate to formal investigation. From there, the variants are categorized into the following: 

• Variants Being Monitored (VBM) - which is all variants, literally
• Variant of Interest (VOI) - Possible attributes of a variant of interest:
• Specific genetic markers that are predicted to affect transmission, diagnostics, therapeutics, or immune escape.
• Evidence that it is the cause of an increased proportion of cases or unique outbreak clusters.
• Limited prevalence or expansion in the US or in other countries.

• Variant of Concern (VOC) - Possible attributes of a VOC include those listed for a VOI and the following:
• Evidence of impact on diagnostics, treatments, or vaccines
• Widespread interference with diagnostic test targets
• Evidence of substantially decreased susceptibility to one or more class of therapies
• Evidence of significant decreased neutralization by antibodies generated during previous infection or vaccination
• Evidence of reduced vaccine-induced protection from severe disease
• Evidence of increased transmissibility
• Evidence of increased disease severity
• Variant of High Consequence (VOHC) - Possible attributes of a VOHC include those listed for a VOI and VOC as well as the following:
• Impact on Medical Countermeasures (MCM)
• Demonstrated failure of diagnostic test targets
• Evidence to suggest a significant reduction in vaccine effectiveness, a disproportionately high number of infections in vaccinated persons, or very low vaccine-induced protection against severe disease
• Significantly reduced susceptibility to multiple Emergency Use Authorization (EUA) or approved therapeutics
• More severe clinical disease and increased hospitalizations

As of October 4, 2021 the CDC has 10 VBMs, zero VOIs, and 1 VOC they are looking at in the U.S. The WHO has slightly different tracking methods since they are looking at global outbreaks. The WHO is tracking 15 VBMs, 2 VOIs, and 4 VOCs. Currently, neither organization has any VOHCs.

Because of these expected variants, infectious diseases have the potential to wipe out whole populations of people unless the virus, and its variants, can be stopped or slowed down with very specific measures. 

1) Social distancing/quarantine 

2) Wearing masks 

3) Practicing good hygiene 

4) Vaccines

What about variants and vaccines? Because of ongoing changes, the vaccines we have now will eventually need to be altered to address those changes. Just like the flu shot each year. Based on the top strains the vaccine is altered each year to target those. Scientists believe the coronavirus may end up, at some point, arriving at the same place - the vaccine being altered each year based on the VOCs. 

Sources: who.int, intermountainhealthcare.org, cdc.gov, indianexpress.com