Calculator Changelog

1/4/2022: Omicron variant vaccine updates

Made first-round updates for Omicron.

• Vaccines
  • Efficacy of vaccines vs any infection has greatlly decreased.
  • Added the option to have a booster dose.
  • Pfizer / AstraZenica data was drawn from Ferguson et al., Table 3.
    • Pfizer multiplier changed to 1, 0.8, 0.25 with 1, 2, or 3 doses respectively.
    • AstraZenica changed to 1, 1, 0.3.
    • Moderna / Sputnik is assumed to be similar
  • Johnson&Johnson data is from Gray et al., calculated from data in table 1 as (Number of positive COVID19 tests With Vaccine / Number of tests With Vaccine) / (Number of positive COVID19 tests without Vaccine / Number of tests)
    • New multipliers are 1, 0.95 with 1 or 2 doses.
  • To handle mixed-vaccines, we are only looking at the most recent dose. This is a simplification to make the UI and research manageable. In reality, e.g J&J followed by Moderna is probably a little worse than 2 Modernas while Moderna followed by J&J is probably a little better than 2 J&J’s.
  • We acknowledge that vaccine efficacy decays over time. We will attempt to add this to the model in the near future.
• Other mutlipliers
  • We do not think Omicron affects the housemate or partner multipliers.
    • Lyngse et al found that the secondary attack rate within households of unvaccinated individuals was nearly identical between Omicron and Delta.
  • We therefore suspect that Omicron also does not affect the hourly multiplier, but do not have data for this.
    • If you have contact tracing data that suggests a new hourly transmission rate, please send it our way.

7/26/2021: Delta variant updates

• Updated transmission and vaccine numbers for Delta variant:

  	Previous	Delta Variant
  Hourly Multiplier	9%	14%
  Housemate	30%	40%
  Partner	48%	60%
  J&J	.34	.36
  AstraZeneca	.4	.47
  AstraZeneca Single Dose	.56	0.76
  Pfizer/Moderna	.1	0.17
  Pfizer/Moderna Single	.56	0.76

• See blog post or Research Sources for more details.

6/22/2021: Add "Average vaccinated person" risk profiles

• Added the option to select the vaccination state of average people
  • Imported vaccination data from JHU and Covid Act Now.
  • See Research Sources for derivation and caveats.

5/27/2021

• Updated constants for under-reporting factor
  • New numbers from COVID 19 Projections December 2020 update.
  • Results in slightly lower prevalence estimates.

4/10/2021

• Added Gamelaya Research's Sputnik V vaccine to the calculator. See the Research Sources section of the White Paper for details.

3/30/2021: Add Johnson & Johnson's vaccine

• Vaccine updates:
  • Added support for Johnson & Johnson's vaccine (single dose, 1/3 multiplier).
  • Improved multiplier for Moderna and Pfizer's vaccines (0.2 -> 0.1) based on new data.
  • Increase wait time before getting the effects of a vaccine (7 -> 14 days). This matches Moderna / AstraZeneca / Johnson & Johnson (Pfizer's was the only study that used 7 days).
  • See Research Sources for rationale.

3/16/2021: Add vaccines to Risk Tracker

• The latest version of the Risk Tracker now supports modeling the risk of someone you are seeing who is vaccinated.

2/21/2021

• Added precaution for being vaccinated. See paper Q&A and Research Sources for details.
• Note: vaccines also reduce the risk of people who you interact with, we just haven't implemented this yet.

2/2/2021

• Remove "frontline worker", "healthcare worker", and "works from home" person risk categories.
• Remove the "Intermediate Method" from the white paper. You can read more about our rationale for this change.

1/28/2021

• Created new mask categories and updated multipliers for mask types. See the Masks section of Research Sources in the White Paper for details.

1/5/2021

• Increased One-time interraction transmission rate from 6% to 9% to account for more contagious COVID variant B117. See blog post for details.

1/2/2021

• Re-labeled "frontline worker" to "healthcare + social worker".
• Reduced risk of healthcare + social workers to 2x average (previously 3x).
• Re-labeled "Not an essential or front-line worker" to "a person who works from home."
• Note This recategorizes people who work outside the home but not in healthcare/social work settings as "An average person in your area."

12/19/2020

• Fixed a bug in which many counties were getting the state's positive test ratio instead of the counties.
• Updated to COVID Act Now's v2 API, allowing positive test rates to sync again.

12/13/2020

• Replaced logic for under-reporting factor, resulting in significantly lower prevalence estimations.
• Previous logic: 6x for positive test rate under 5%, 8x for 5%-15%, 10x for above 15%.
• New logic from COVID 19 Projections
• See Research Sources for more details.