COVID-19 Diary – Day 198

A recent study conducted at the University of California, Davis, has provided some new information that could relate to the effectiveness of homemade non-medical masks.

The study began as a comparison of different types of masks, including surgical, vented N95 and KN95 rated masks, as well as paper towel, and both single and double-layer cotton t-shirt masks (see above image). Then, using an aerodynamic particle sizer, they had 10 different volunteers breath, speak, cough, and move their jaw (as if chewing gum) while breathing through their nose, both while wearing a mask as well as without. The goal was to count the number of particles from 0.3 to 20 μm in size, being expressed from the activity, and compare them.

The results showed a consistent and significant reduction in particles expressed when the KN95 and surgical masks were in use, compared to not wearing a mask. The vented N95 mask also showed a reduction in expressed particles, but not to the same degree as the above-mentioned masks. The paper mask however offered no statistically significant difference in particle numbers, and both the single and double-layered cotton masks actually showed a significant increase in particles vs wearing no mask.

Figure 2
Figure 4

It is important to remember while reading this information, that the above study is not testing for COVID-19, but rather for particles that could conceivably carry COVID-19. It is believed that particles released from the cotton masks themselves confounded the results of the test, but the question remains on if aerosolized fomites could lead to COVID-19 transmission, which is an answer we do not have yet. We do however know that COVID-19 can survive on cloth for up to 2 days. The researchers themselves have said:

“as a precaution, our results suggest that individuals using homemade fabric masks should take care to wash or otherwise sterilize them on a regular basis to minimize the possibility of emission of aerosolized fomites.”

Fomite (Surface) Transmission

Speaking of fomites, here is a list of how long COVID-19 can survive on different kinds of surfaces, courtesy of The New England Journal of Medicine, and The Lancet.

  • Aluminum (foil, window frames, ladders, etc.): 2-8 hours
  • Paper (mail, tissues, toilet paper, magazines, newspapers, etc.): 3 hours
  • Copper (coins, jewelry, wires, etc.): 4 hours
  • Cardboard (shipping boxes, food packaging, etc.): 24 hours
  • Cloth (bags, bedding, blankets, carpet, hair bands, etc.): 2 days
  • Wood (furniture, tabletops, etc.): 4 days
  • Plastic (light switches, credit cards, food packaging, ATM buttons, etc.): 3-7 days
  • Metal (utensils, keys, pots and pans, door handles, etc.): 5 days
  • Glass (glasses, stemware, windows, mirrors, etc.): 5 days
  • Face masks (exterior): 7 days

AstraZeneca Vaccine Update

Despite the news that AstraZeneca’s COVID-19 Vaccine Candidate is showing signs of causing transverse myelitis in some study participants, yesterday Trudeau and the Canadian Vaccine Task Force announced a deal for 20,000 doses should it be approved for use. This makes the 6th arrangement Canada has entered into for COVID-19 vaccine candidates, the first deal for one with known potentially serious side effects.

This news came at the same time as the European Union entered into an agreement to pay claims above an agreed limit against AstraZeneca over side-effects from its potential COVID-19 vaccine, in exchange for a decreased price for the product itself. This kind of agreement is not the first for AstraZeneca with this vaccine candidate, as we know many other countries (including the US) have also agreed to limit or remove liability over possible side effects. It is not currently known if Canada has made a similar agreement.

That’s all for now, stay safe everyone!

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