This is a COVID Update. I’ll also talk about a recent meta-study by Jefferson et al about mask effectiveness.

The Winter wave is over.  Cases in the US, California, and San Diego County are about at the same level as they were in October.  This the mildest COVID winter season since the pandemic started.  COVID related deaths increased modestly during this time, but are now relatively low but persistent.

World wide, cases are as low now as they were way back in the Summer of 2020. Of course, I have to mention that testing was not as available in 2020 as it is now.  On the other hand, many people currently are testing themselves with over the counter tests, and don’t report the results to the medical system, so there is a lot of uncertainty as to the actual number of cases.

Cochrane Report on the Effectiveness of Masks:  Jefferson et al released a meta-study through Cochrane Reviews on the effectiveness of medical masks (surgical masks) and medical respirators (N95) in public settings.  A meta-study is a study in which the authors gather information from published articles and try to draw conclusions from a large body of data. They do not gather a new set of data.

The Jefferson et al study reviewed 78 different studies, including data from pre-COVID flu outbreaks.  Their conclusions are sobering.  First, the authors suggest that there is virtually no benefit to wearing a medical surgical mask over not wearing a mask in most settings.  If you’ve been reading my blog for long, you will know that this conclusion does not surprise me.  Blue surgical masks have large gaps in the sides and do not filter air leaving the mouth and nose.  They were designed to prevent droplets from a medical worker from contacting a patient, not to prevent transmission of aerosol based agents.  This is a problem, since most mask wearing people in public during the pandemic were wearing surgical masks.  These people thought they were protected from aerosols, but they were not.

The study also concludes, however, that N95 masks didn’t perform much better.  In fact, for lab tested COVID, the difference was statistically insignificant, meaning that the difference between wearing N95s or surgical masks was so small, it could not be proven to be a real difference statistically. 

I have to point out that the Jefferson meta-study points out that many of the studies they reviewed had various failings that may have made them unreliable.  Much of the data was collected through self-reporting of participants, which is a source of inaccuracy, and participants were often non-random, making application to the general population difficult.  So some of the conclusions may have suffered from these kinds of errors.

As you know, I’ve been a proponent of wearing N95, KN95, or KF94 masks when indoors during the pandemic.  Unfortunately, N95s are tight and intolerable for most people for long periods, so most people didn’t want to wear them at all.  Those that did were not careful to make sure the mask fits properly, making the mask ineffective.  This is part of the reason I wore a KF94 (Korean) during the later stages of the pandemic when I had choices.

So have I been wrong this whole time?  Well, yes and no.  I wore a KN95 in all kinds of environments while traveling during the pandemic.  When I finally got COVID in January of 2022, I was not wearing my mask, working in a “gray area” environment with people that I later found out had COVID.  I was technically indoors, but the room had a lot of ventilation, so I thought I would be OK. Obviously, I was incorrect.  All this to say, I think my KN95 was effective for much of the pandemic.  On the other hand, I am a scientist in the infectious disease field, and have had a lot of experience wearing and fitting these masks to myself, so I am not a typical user.  It may certainly be that my experience does not translate to non-scientists.

If you still have not had COVID and are not high risk, I might say that the current version has an extremely low fatality rate, and it may now be worth the risk to say good-bye to the mask.  I know the large majority of you have done this already.

If you are at high risk, I still think an N95, KN95, or KF94 can be effective for you.  In order for it to be effective, however, you need to make sure it is properly fitted, making sure you don’t have gaps between your nose and cheek.  The mask should filter the air coming into your nose and mouth.

Since I had COVID last January, I no longer wear a KN94, and enjoy eating indoors in restaurants again.  I’ve basically been back to normal for a long time.

Dr. Visay Prasad has an excellent video describing some of the details of the meta-study.  He is an epidemiologist from UCSF. 

Don’t fear, but be smart,
Erik