Where Do We Begin…
If I’m being honest, I was really tired last week. Tired of arguing against misinformation, tired of battling on the side of health instead of politics or wealth, tired of waiting for decisions mired in lawsuits and indecision…
Then the weekend was long, the weather changed, and I worked through a very complex data problem reminding me that epidemiology is an invaluable asset right now.
Let’s start by talking about the vaccine.
A vaccine at the end of October would be remarkable.
Will it be safe? It may pass an expedited review process, but there is little reason to believe it will not be safe. The two top candidate vaccines are mRNA vaccines (one made by Moderna, the other Pfizer). When injected, the mRNA particles in the vaccine will cause your body to create warriors to the predominant COVID-19 surface protein (think of it as facial recognition programming for pathogens).
Will it be effective? I have more hesitation on this point than any other. Targeting the main surface protein and its variants should be efficacious, but there are many unknowns. How long will it protect? Will everyone generate a response? Will older populations be protected (they require a highly concentrated dose of the flu vaccine)? Because of the expedited timeline for development of these vaccines, we will not have the answers to these questions. All we will know is that the vaccine is likely safe and generates some level of immune response.
How soon will everyone have access to the vaccine? This will take time, which honestly means there is more time to make sure the vaccine hits the right marks. Early doses will be in small quantities (a million sounds like a lot, but that probably only covers 500,000 in the entire US if two doses per person are required, given one month apart). Manufacturing more than 600 million doses for the US will take months, if not through most of 2021. WHO estimates two billion doses will be available worldwide by the end of 2021.
The good news…there are many other vaccines in the pipeline which will likely be more suitable for longer term and broader coverage in future years. If COVID-19 becomes a seasonal, sustained phenomenon, we may need to add the COVID-19 vaccine to our regular regimen of immunizations.
The bad news…we’re in for a long winter. There is no way around this. Academic models show COVID-19 deaths doubling to more than 410,000 by the end of year. We have to stay vigilant.
In other news…PCR tests, mortality counts, and the silver lining
False positives and PCR cycle times
In general, the PCR test will result in a small number of false negatives. False positives are rare, especially right now when disease prevalence is high. A few notes about the test –
· PCR tests are excellent and robust at finding the right pathogen when it’s really in your body
· There’s been debate about the cycle times being set too high for the COVID-19 PCR, therefore detecting more positives than truly represent infection. Cycle times (CT) are the number of times viral genetic material are replicated in a test. The CT is set in the development phase of the test. I honestly do not feel this is a valid concern at this time. The test is not intended to differentiate between active infection and the presence of viable virus. Our goal is to find as many people with the virus in their body as possible to limit spread of the virus. The PCR test does this validly and reliably. [I personally helped develop a PCR test to identify Mycobacterium chelonae in metal working fluid from a John Deere plant. That pathogen causes hypersensitivity pneumonitis. Yes, I played around with cycle times, but once you know that threshold and repeat it, you can trust it.]
COVID-19 mortality counts
Some were alarmed to hear this quote from a CDC article last week, “For 6% of the deaths, COVID-19 was the only cause mentioned.” Death certificates are tricky. It may be true that only 6% of COVID-19-related deaths were caused ONLY by COVID-19, but most will list COVID-19 as a significant or contributing factor meaning the death would not have occurred when it did without the COVID-19 infection. There is no question the US experienced significant excess mortality due to COVID-19 from the start of the pandemic (see reference from the National Center for Health Statistics).
For example, obesity (BMI ≥30) is a risk factor for severe COVID-19 infection. As of 2018, 42.4% of the population fell into this category. A person with obesity who dies from a COVID-19 infection will have COVID-19 and obesity listed on their death certificate, not just COVID-19.
The silver lining
I’m starting to see some remarkable examples of resiliency, primarily in sport. We’re finding ways to come together, distanced and masked, to swim, run, bike, and play ball. There might not be fans, and we can’t play all sports safely, but it’s been wonderful to see.
A final critical note, GET YOUR FLU SHOT. Get it this month, even if you’ve never had one before, get one now. It has never been more important.
Stay safe and healthy 😊.
References:
COVID-19 deaths - https://www.kctv5.com/coronavirus/questions-remain-over-weekend-cdc-mortality-rate-announcement/article_7247900c-ebdb-11ea-97d9-0bb46daa0a9f.html
COVID-19 predicted deaths - https://www.washingtonpost.com/health/experts-warn-us-death-toll-could-hit-410000-by-years-end/2020/09/04/ffc34736-eea7-11ea-99a1-71343d03bc29_story.html
US obesity rates - https://www.cdc.gov/obesity/data/adult.html
COVID-19 mRNA vaccines - https://www.nature.com/articles/d41573-020-00151-8
Vaccine tracker - https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html
Vaccine early successes and challenges - https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31867-5/fulltext
NYT PCR testing - https://www.nytimes.com/2020/08/29/health/coronavirus-testing.html