What a Difference Six Weeks Makes

Dear Members of the Baylor College of Medicine Community,

What a difference six weeks makes. The CDC released new guidelines last week. Do they make sense for Texas? My short answer, yes. However, this is COVID-19. Yes-no questions are always subject to cautions and caveats.

In early April, the CDC released new guidance allowing those who are vaccinated to take some baby-steps toward normality. The vaccinated were now deemed safe to gather in small, private settings, with others who are vaccinated without masking or distancing. I commented at the time this seemed to be an extraordinarily timid step, and that the CDC recommendations were really following what people were largely already doing.

Six weeks later, we have new recommendations. I strongly encourage you to read them in their entirety, as I will not fully review them here, and there are important nuances. Notably, healthcare facilities and travel are treated much more cautiously. However, at the heart of the new guidelines is this: If you are vaccinated, you can (in most cases) take off your mask, stop social distancing, and largely return to your pre-COVID normal activities.

This announcement took many – me included – by surprise. Before I get too critical of the CDC, let me freely acknowledge that their decisions are driven by real experts in epidemiology, infectious diseases, and related disciplines. They have broad access to data and details of the emerging science. I have respect for the hard work they do. However, I do wish they would invest in some better advice on communications and public relations. I often read the issued public guidance and feel like I am interpreting cryptic utterances of a Delphic oracle.

Fundamentally, it appears what the Oracles of Atlanta are saying is the following:

If you are vaccinated, you are (relatively) safe. You are unlikely to get infected, and you are unlikely to infect others.

If you are unvaccinated, you need to continue to follow safe practices (mask, distance, avoid crowded indoor spaces).

There appear to be two major factors driving the new recommendations. First, new data is emerging from real-life situations that are building confidence in the efficacy of our vaccines. It is increasingly apparent that if you are vaccinated, you are highly unlikely to develop a severe case of COVID-19. Breakthrough infections do occur, and they can still be severe, but they are rare. In addition, there is emerging evidence that if vaccinated, and if transiently infected with SARS-CoV-2, viral replication and shedding is reduced in your upper respiratory tract. Not only are you unlikely to be infected, but you are unlikely to infect others.

The emerging data are encouraging, but there is a second important factor to consider – the overall disease prevalence in the community. In early April, I wrote why high community disease prevalence should result in continued masking, even in fully vaccinated people. In brief, even a highly effective – or said another way, a slightly ineffective – vaccine is not completely protective in a high prevalence environment. If you enter a room packed full of mosquitos, you will still be bitten even if protected by the best insect repellent. Crowding into Minute Maid Park when we have a high prevalence of COVID-19 is still risky, even if vaccinated.

Are we in a high or low prevalence environment? Harris County, after 47 consecutive weeks at their highest possible COVID-19 threat level, on Monday finally lowered the level a notch. This decision was based in part on the low number of new COVID-19 cases and decreased hospital utilization, signs we are in a lower prevalence environment. The Texas Medical Center metrics we have followed so closely for so long continue their steady decline, reaching levels we have not seen since September, and in some cases approaching Spring of 2020.

Is the disease prevalence low enough to feel relatively safe? Note, when talking about safety I am always compelled to use a modifier – relatively. Complete safety is unobtainable. No matter how much caution is exercised, there are few human endeavors that meet the standard of complete safety – no medication, no car trip, no sports participation. The question is, if someone is vaccinated have we reached a point of relative safety with COVID-19 where we can abandon our now-longstanding viral control practices, as the CDC recommendations seem to imply? Are we comfortable with the risk? After thinking about this for the past week, and discussing with several colleagues, my answer to that question is yes. I agree with the CDC (I doubt they have lost much sleep waiting for my opinion).

Have we reached a level where (if vaccinated) we should feel comfortable shedding our masks and aggregating indoors? Another useful way of thinking about our tolerance for this risk is to compare our current COVID-19 community disease burden to that of influenza. We have an influenza outbreak annually, usually between October and May, and peaking at variable points during the winter months. We – the health care delivery systems of the nation – ramp up efforts to control flu. We encourage our patients to be vaccinated. Some communities mount modest public education campaigns. Many health care providers require employees to be vaccinated against flu. Hospitals see a predictable and expected surge in admissions, often of critically ill patients. The annual flu surge transiently strains resources but come nowhere close to the breaking point. Nationally over the past decade flu kills between 12,000 and 61,000 people in the United States.

How do we react to flu? We do not push people to wear masks (although to be honest, next flu season in crowded places I will think about it). We do not shut down schools. Restaurants stay open. Sports arenas are packed shoulder-to-shoulder. Houses of worship are full. Live cultural performances continue. Except in very unusual and very limited circumstances, nothing is shut down. We live with the risk of flu – relatively safe – and go on with our lives. Most people outside of healthcare are not even aware it is an issue. It is a serious disease, people die, but as a society we appear to be comfortable with this risk.

I think it follows that when the COVID-19 disease burden starts to look like that of our typical flu season, we should be comfortable lifting most restrictions. To gauge disease burden, let us look at current and historical mortality data for Pneumonia, Influenza and COVID-19 (PIC).

The most recent data are from two weeks ago and may still be subject to some reporting lag. During that week, if you look at all the people who died in the US, 10.9% died from PIC. Compare that to the first week of January, where a stunning 33.7% of all deaths were attributable to pneumonia, influenza or COVID-19.

Let us compare the current state to the worst flu year in the past decade – 2017-18. The total deaths attributable to PIC conditions during our worst flu outbreak? 10.9%. Exactly the same as today. I spent a lot of time over the weekend looking at different methods of comparing historic flu to current COVID-19. I have talked to front-line providers to ask what the disease burden in hospitals feels like currently. I am increasingly confident that our disease burden is approaching – just recently – the disease burden of our worst flu outbreak of the past decade, and continues to trend downward.

Always with COVID-19, there are cautions and caveats. In this case, regional variability is important. If we drill down on the same “percent of total deaths attributable to PIC” metric for Texas, we look even better than the national picture. PIC conditions are currently responsible for 9.0% of our deaths in Texas. We peaked during the first week of January at 40.2% (of every 10 people who died in Texas that week, 4 died from PIC). How does our current 9.0% stack up to the worst flu year? In the peak week of 2017-18, PIC was responsible for 13.3% of total deaths, more than we are currently experiencing.

As an example of regional variability, Michigan looks materially different, as do most states in the Northeast. PIC is currently responsible for 17.6% of Michigander deaths (compared to 10.9% nationally and 9.0% in Texas). The disease burden (and presumably the prevalence of severe disease) is about double that of a severe flu year in Michigan. In Texas, it appears our disease burden has steadily declined over the past two months to approximate a moderate to severe flu year.

Regarding the recent CDC guidelines (in my opinion):

• If vaccinated, in Texas, you are relatively safe to remove your mask and eliminate distancing – even indoors. Remember, there is no such thing as complete safety.
• If unvaccinated, you are still at substantial risk, and should – for your own safety, continue to mask, distance and avoid crowded indoor spaces. Here is an even better idea: get vaccinated. Vaccinations are remarkably safe, effective, available and free.
• If I walk into an indoor space without a mask, how do I know everyone else is vaccinated? You don’t, and it doesn’t matter, at least not to you if you are vaccinated. It does matter to the unvaccinated people in the room, who remain at risk. This is perhaps the biggest change underlying the CDC recommendations. If you are vaccinated, you are unlikely to become infected, and you are unlikely to spread the virus to someone else.
• It is reasonable for businesses, houses of worship, etc. to consider relaxing or eliminating distancing and masking restrictions, particularly if our favorable trends continue for the next couple of weeks. If uncomfortable, private businesses clearly have the right to keep restrictions in place.
• Businesses should strongly encourage the unvaccinated to continue to mask and distance. Business’ approach to their employees will vary (e.g. vaccine requirements, employee attestation of vaccine status). It does not appear we will have a reliable method of assessing the vaccine status of patrons (like a vaccine passport). As our COVID-19 numbers continue to improve, and more are vaccinated, the risk of the unvaccinated choosing to follow unsafe practices will become less about protecting the public health, and more about protecting the individual health of those who are unvaccinated.
• For vaccinated individuals who are particularly at risk (for example, immunosuppressed from chemotherapy or a medical condition), it is prudent to continue to mask and distance. This advice would also apply during a normal flu year.
• Remember, some environments should not relax restrictions – hospitals, medical clinics, nursing homes.
• If you happen to be reading this outside the greater Houston area, pay attention to your local disease prevalence. If you are still in a “hot” area of the country, you may want to proceed with more caution.

The situation is clearly improving, and we should celebrate where we are right now. The biggest risk of a major resurgence would be the emergence of a true “variant of high consequence” that is immunologically resistant to our current vaccines. That hypothetical threat is real, but in the worst-case weeks to months in the future.

For now, it is appropriate to take a deep breath, relax a little, and take our next step towards normality.

James T McDeavitt, M.D.
Executive Vice President and Dean of Clinical Affairs

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