February 20, 2021

We are Reaching Half-A-Million COVID 19 Deaths in the United States.

By the end of Monday 22nd February 2021, we will pass through and above 500,000 deaths from COVID19 in the United States. I calculate and plot the doubling time in days averaged over a moving 7-day period. Doubling time, based on the previous seven days average, as of the end of 2020 had dropped below100 days. The doubling time for US deaths from COVID19 is increasing again early in 2021, as seen in the current graph below.

February 11, 2021

What are the Special Syringes for More Vaccine Doses?

You have heard about the idea of getting an extra dose out of a vaccine vial? It is on the news regularly. The Pfizer vaccine comes in a volume to get 5 doses, but there is some extra volume provided to allow for getting those 5 doses. Then, if you have a special syringe you could get a sixth dose.

How? 

A regular syringe will empty a few hundred microliters of liquid when the plunger is pushed. When the plunger reaches the end of the regular syringe there will still be some liquid in the small channel between the plunger and the start of the fitted needle and inside the needle itself. This is called dead space volume and it can be 70 to 90 microliters. After five uses that adds up to about 400 microliters, almost half of a 1 milliliter (1 cc)  syringe, or at least one extra sixth dose.

There are, however, syringes like special insulin syringes that come with an attached needle and have a very thin, and very short channel between the plunger and the needle. Some have a thin plunger extension that also pushes into the thin channel. As a result of this, these syringes have a very low dead space volume, from 2 to 5 microliters. So, if you have these low dead space syringes, you do not lose that 400 microliters after five injections, so several hundred microliters remain in the vial to give you one more shot. The six shooter!

Ken Mitton

February 6, 2021

New Covid19 Variants Can Infect Those Who Had Covid19 Before. Vaccination Protects Better.

It looks like the newly adapting Covid19 variants can reinfect persons who had the illness before. There is emerging evidence from the UK that this is a new concern. However, there is also emerging evidence that vaccinated persons are more resistant to illness and infection from the same new variants. The South African variant is one example of the newly evolving Covid19 strains. 

Some preliminary testing has been done using patient blood serum from persons vaccinated with various versions of the vaccines now in use. Here is what we know as of early February 2021.

  • The Pfizer two-dose vaccine (RNA type) seems to generate serum antibodies that react and bind well to the spike protein of the South African variant.  The paper reporting this is not yet peer-reviewed in a journal but it is pre-print public here: https://www.biorxiv.org/content/10.1101/2021.01.07.425740v1
  • Other vaccines in the process of approval review in the UK seem to offer some reactivity to protect against the new South African variant too, as reported in this BBC news post: https://www.bbc.com/news/uk-55850352
  • Oxford-AstraZeneca's vaccine offers limited protection against the new variant but the company is also now developing a second version of the vaccine to match the amino acid changes in some of the new variants that are evolving around the world.

So, for those persons who had Covid19, their immunity after a real infection may not be a justification for skipping vaccination. I am signed up and eagerly awaiting my turn. I will gladly get vaccinated and I suggest you get it too even if you have recovered from a covid19 infection. 

Ken Mitton
The Science Rant