San Mateo County COVID-19 Data One Month After Reopening

Our community is now a month into its reopening and slightly less than a month away from the reopening of our high schools. We can still screw it up!

Appended at the end of this article are screenshots from the San Mateo County Health Data Dashboards as of the morning of 7/16/21.  Case data can be found at and vaccination data at  The third picture in the series shows graphs going back to the start of the pandemic, while the fourth picture’s graphs zoom in on the past 30 days which coincide with our “reopening.”  Also realize that case counts do not describe the entire picture, e.g., vaccinated people who just get a very mild case might not bother to test for COVID because they think that they “just have a cold.”

Cases remain low but have been steadily rising since the June 15th reopening as expected.  The Reff value is up to 1.19.  Vaccination rates are excellent except in the 12-15 and 16-24 age cohorts.  Sadly, the county uses different age cohorts in reporting the case data versus the vaccination data which complicates comparisons.

It is important that we continue to vaccinate eligible minors before the school year starts.  Even though the current vaccines appear to protect people from serious illness from the currently predominant Delta variant, there are sufficient reports of vaccinated people getting sick that problems could still result when kids go back to school.

Eric Feigl-Ding is an epidemiologist and health economist with the Federation of American Scientists.  He recently passed along on his Twitter feed the link to the following article written by a North Carolina pastor.

The pastor, his wife, and their older son were all vaccinated (Pfizer shots), but their 11 year old daughter was not.  They left on a family vacation and the daughter became ill.  They didn’t get her tested immediately, but it turned out to be COVID.  Because they were traveling in close contact with her without masks, the rest of the family also became ill despite being vaccinated.

While this is an anecdotal story, not a research study, it appears to indicate that, while the vaccine protects one from serious illness, it does not prevent one from getting ill if exposed to “enough virus” and then feeling pretty crummy for possibly an extended period of time.

In addition, according to Dr. Bob Wachter, Chair of the UCSF Department of Medicine, long COVID can hit those who only get mild symptoms; they just do not have sufficient data on this topic yet (see ), so Dr. Wachter continues to recommend masks when in close quarters.  He states “As for me, I’m back to double-mask in stores. Still indoor dining but might abort if trends continue.” : .

Let’s please continue to exercise prudent precautions and not have to learn yet again how “devious” this virus can be.

There are higher priorities in life than hanging out in bars without masks, simply to express “our freedom”…

Being able to educate children at school should be one of them.

Author: David Kristofferson

Retired Ph.D. scientist, teacher (after retiring from industry, taught in private and public high schools and then worked a decade in my own private tutoring business), bioinformatician (managed both the NIH-funded GenBank National Nucleic Acid Sequence Databank and the BIONET National Computer Resource for Molecular Biology), IT director at Eos and Raven Biotechnologies, software product manager, AAAS Fellow, avid cyclist, and backpacker!

6 thoughts on “San Mateo County COVID-19 Data One Month After Reopening”

  1. An interesting and somewhat upbeat article on “long COVID” came out today in the SF Chronicle. The reporter interviews many prominent Bay Area doctors, and it is well-written. However, *please* be sure to read the *entire* article as there are several caveats and qualifications expressed at various points in the article. I am not going to attempt a 5 second summary here.

    If you’re fully vaccinated, what’s your risk of ‘long COVID’?


  2. On July 16th I posted a warning on Nextdoor ( – link not accessible without a local Nextdoor account) to vaccinated parents who might have to care for an unvaccinated child who contracts COVID – Be sure to wear masks, isolate the ill child from the rest of the family and use careful hygenic practices even if you are fully vaccinated.

    This stemmed from reports mentioned in that post of COVID cases in vaccinated people that are described as “mild.”

    One of these reports was from a pastor in North Carolina who went on a family vacation (parents and 16 year old son were vaccinated, but 11 year old daughter was not – all caught COVID after the daughter was infected.)  The pastor described his symptoms and experience in the following three paragraphs.


    “I’m hopefully in the worst of it now: congestion, headache, body aches, cough, fatigue, etc. I lost my sense of taste and smell (which for a devoted foodie is torture) but overall it feels like a very bad cold, which feels like good news. I shudder to think how bad it might have been had we not been vaccinated.

    If I could share a few words with you, they would be these:

    Please get vaccinated if you haven’t. It’s the only way we’re going to get the edge on these dangerous variants and it will keep you from the worst symptoms and very likely save your life. The ferocity and speed of the mutations of this virus are startling. Once you are vaccinated, don’t let your guard down. You are protected but you’re not invincible.”


    I have been trying to find the medical definition of COVID “mild symptoms” and was provided on 7/21 in the earlier Nextdoor post cited above with the definitions text by Thomas Kakuda (who works in public health but I do not know his precise job title).

    His note is buried in that older post which is now submerged far down in the newsfeed, but I think that it is important to pass this information along to others because this medical definition of “mild symptoms,” as I feared, does not seem to me to correlate with what most laypeople would understand as “mild.”

    You will see below that “mild symptoms” are mainly defined as having COVID *without shortness of breath or abnormal chest imaging.*  You may feel like a sack of garbage, to be polite, but still fall under the definition of having “mild” symptoms!!

    Here is the definition text provided by Thomas Kakuda in the older Nextdoor post:

    Mild Illness: Individuals who have any of the various signs and symptoms of COVID-19 (e.g., fever, cough, sore throat, malaise, headache, muscle pain) without shortness of breath, dyspnea, or abnormal chest imaging.

    Moderate Illness: Individuals who have evidence of lower respiratory disease by clinical assessment or imaging and a saturation of oxygen (SpO2) ≥94% on room air at sea level.

    Severe Illness: Individuals who have respiratory frequency >30 breaths per minute, SpO2 3%), ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) 50%.

    Critical Illness: Individuals who have respiratory failure, septic shock, and/or multiple organ dysfunction

    The definition text above is from the National Institutes of Health (NIH) at


  3. In the Nextdoor discussion on this topic a reader commented, “The only ones continuing to spread covid are the unvaccinated.” Not completely true. The following quotes from two Bay Area doctors are in today’s Chronicle (I added the ***’s in the fourth paragraph for emphasis).

    “Dr. Robert Wachter, chair of the UCSF Department of Medicine, said that the numbers — while worse than he thought they would be a month ago — are “not a disaster,” but indicate that even in areas with high levels of vaccination, the unvaccinated are still at significant risk.

    “What the last month has demonstrated is that even three-quarters of a population vaccinated in the face of a virus that’s twice as infectious is not enough to prevent significant amounts of spread,” he said.

    Dr. Julie Parsonnet, an epidemiologist at Stanford said that while vaccinated people shouldn’t be worried by these numbers, they do indicate that herd immunity — the idea that enough people would be vaccinated to stop the spread of the virus — is out of reach.

    *** “It seems likely to me given these patterns that people who are vaccinated are capable of transmitting” even if they don’t get sick, she said. “So if you’re not vaccinated, you’re going to get the virus.” ***

    “We need to vaccinate everyone to protect the people who are at the highest risk,” she added.”

    The article is at:

    S.F.’s coronavirus case rate has spiked above California’s. What’s going on?


  4. The following is a comment that I wrote today for Nextdoor:

    I should also respond to Tawni’s post about being skeptical of groups like the CDC, AAP, etc., particularly in light of my recent comment here that the CDC may have told vaccinated people to cut back on COVID testing prematurely.

    Back in 1993 or 94 I gave a packed, invited lecture at CDC in their main cavernous lecture hall on the importance of connecting biological research organizations to the Internet. I was a leader of the charge for this, funded to do so by the National Science Foundation and NIH, and spoke around the country at academic, corporate, and government research centers as well as to large groups at scientific professional conferences. I was later elected a fellow of the American Association for the Advancement of Science for this work, and I am very gratified to see how the fruits of those efforts played out over time, particularly during this pandemic.

    What I did not anticipate was how all of this work would be threatened by propaganda efforts later, many launched via the Internet.

    I agree that the CDC has made mistakes during the pandemic, and it may look like they are “moving the goal posts.” Unfortunately this attitude has been pushed by right wing media like FOX News which simply plays on the people’s confusion to sow doubt, so that FOX can promote its political agenda.

    I never saw these organizations as nefarious or “fake.” They were populated by scientists and doctors trying to do their best in a very uncertain world to promote public health. When it looks like CDC may be “moving the goal posts,” instead of believing that this is a nefarious push for “social control” and “taking away one’s liberties,” I would politely suggest that people first try to understand what new information might have come available to warrant such a change. Unfortunately, if one gets their news from Tucker Carlson, the odds of one learning that new information is small compared to the odds of hearing repeated screeds about the CDC’s supposed “lack of credibility.”


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