Note: I graduated from Caltech at the end of 2022 and am no longer maintaining this page.

To see the daily case counts for the last 90 days, please use the toggle. Drag to view other dates.

The World Health Organization declared a global pandemic due to COVID-19 on 11 March 2020. On 16 March 2020, Caltech officially closed, with undergrads not returning to campus after spring break and graduate students, staff, and faculty staying home. After 3 months at home, Caltech laboratories reopened on 8 June 2020 with modified capacity and safety protocols, and Caltech has been gradually returning to full capacity since then.

Events correlating with increases in COVID-19 cases:

• 2022-03-17 – 2022-03-25: Spring break
• 2022-05-20: Graduate Student Council Formal
• 2022-05-27: Undergraduate social trip

Note: for summer 2022, students who are visiting researchers are classified as employees.

How does Caltech compare with LA County?

To highlight points on one plot and see the corresponding points on the other, please use the box select or lasso select tool.

Caltech does not report the total community population or campus density, so we cannot compare case rates directly with the surrounding community, Los Angeles County.

Instead, we can use unsupervised machine learning to find patterns. Using a variational Gaussian mixture model with a Dirichlet process prior, we detect 4 groups of dates, corresponding to different ratios of the Caltech daily average number of cases to the LA County daily average number of cases. From spring break through mid-July 2022, we were consistently in the highest ratio cluster. Ahead of Labor Day weekend 2022, Caltech and LA County cases are trending downward, as is the Caltech/LA County case ratio.

If the Caltech population exactly mirrored the greater community in terms of behavior (level of socializing and masking, going to stores/concerts/etc.) and testing, we would expect a strong correlation between Caltech cases and LA County cases, with a slope equal to the ratio the total number of Caltech community members to the total LA County population. However, this is not the case. It is unclear from the available data whether the different ratios arise from different rates of transmission to and between Caltech community members compared with LA County residents, and/or from a high level of surveillance testing (many students and employees test twice per week) detecting cases among asymptomatic Caltech community members.

Data sources

Caltech data transcribed manually from the Caltech Case Log. Date indicates the date that a case was posted on the case log (not the date of a positive test). CCC indicates Children's Center at Caltech. Omitted cases where the person had not been on campus in the last month.

LA County data with rolling averages sourced from the NY Times Github.

The data is split between .csv files by year. Raw files: 2020 / 2021 / 2022.

Data tools

All data analysis and visualization performed in Python.

Analysis	Visualization
NumPy	Bokeh
Pandas	HoloViews
SciPy	Colorcet
scikit-learn

caltech_covid19 is maintained by lealiaxiong.