18 March 2022 Blog Post : On COVID Deaths

18 March 2022 Blog Post : On COVID Deaths

Death is never comfortable to talk about, but as we approach 1 million US deaths from COVID-19 (now at 969,000), it is instructive to look at mortality due to SARS-CoV2 infection. Conceptually I break the pandemic into three distinct parts when considering COVID-19 mortality: pre-vaccination, widespread vaccine availability and vaccine plus early treatment.

Figure 1 below shows mortality rates by week in Los Angeles County from March 1st 2020 through the week ending January 12, 2021. Pfizer received vaccine approval in mid-December but, initially, rollout was for healthcare workers but by mid-January, those in higher risk groups began receiving the vaccine. Case rates fell between 0.3 and 0.4 daily deaths per 100,000 through the Spring and Summer, dropping to 0.1 in the Fall before rising sharply during our Winter 2020/2021 disastrous surge. It was during this surge that Los Angeles was the epicenter of world cases.

The second time period to consider was that during which vaccines were widely available but early outpatient therapeutics had not yet come to market. While the first biospecific treatments were approved in May of 2021, Paxlovid did not receive approval until December 2021. Given that many treatments were earmarked for more highly impacted areas (such as Florida, Texas and Georgia), many of these treatments were not widely available until October or November 2021 in Los Angeles. So I mark the termination of the second phase of the COVID-19 mortality pandemic as November 1st, 2021. The sharp decline and the massive effectiveness of vaccination in preventing death from SARS-CoV2 infection is clear even from a simple graphical representation of these data (Figure 2). 

The effect of the Delta variant is evident in the increase in mortality rates beginning in early August and extending through the Fall of 2021. Mortality from Delta peaked in mid September at 0.3 daily deaths per 100,000 before declining and leveling off at a low rate (0.1 daily deaths per 100,000) thereafter.

The last time period to consider is from early November 2021 until present day when the highly infectious Omicron variant led to a massive increase in cases. In Figure 3 below, the mortality rate in Los Angeles County peaked in early February at 0.8 daily deaths per 100,000 population. While this rate is far below that of the January 2021 peak (2.8 daily deaths per 100,000) it nevertheless demonstrates the significant population impact it had upon the health of the County. It is unclear how much impact therapeutics made in attenuating this mortality rate given that many monoclonal antibodies showed such a decreased efficacy that institutions largely stopped providing it. Paxlovid was quite difficult to find as well, especially in January and February.

In all of the debate surrounding COVID-19 along with the impact and the effect of various mitigation strategies in protecting the public’s health – there is one aspect that has near universal agreement.  Vaccination is an effective tool in prevention of severe outcomes and death with SARS-CoV2 infection or breakthrough. While a variant such as Omicron that is highly transmissible can impact this protection at the population level (as can a variant like Delta that was associated with more severe disease, but was less transmissible), the highly effective and protective role of vaccination is seen convincingly across the graphs of the three phases of the pandemic. 

While I am hopeful that early therapeutic intervention will further reduce future mortality rates, the relative lack of availability of Paxlovid and the decreasing efficacy of monoclonal antibodies made them less impactful vis-a-vis Omicron. Tools such as that developed by Rob Relya will allow for further transparency of their geographic allocation and deployment across the US.  Link: https://rrelyea.github.io/

𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿

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17 March 2022 Blog Post: On BA.2

17 March 2022 Blog Post: On BA.2

News from England and Germany suggests that the BA.2 variant (the so called “stealth subvariant”) is causing a significant uptick in cases in Europe. According to a MSNBC article, “

Covid cases have increased dramatically in the U.K. in recent weeks, and Germany continues to mark record high daily infections with more than 250,000 new cases a day.”

(link: https://www.cnbc.com/2022/03/15/is-omicron-subvariant-bapoint2-to-blame-for-rising-covid-cases.html).

When looking at an epidemic curve, however, the numbers tell a somewhat different story (Figure 1 below). Indeed Germany is reporting a significant number of cases (about 225 new daily cases per 100,000 – for comparison Omicron topped out at 453 new daily cases per 100,000 here in Los Angeles County). I’ve added recent LA County case data as Figure 2 below But notice that Germany did not experience the Omicron surge seen in both the US and UK with cases rising through December and peaking in early January. The BA.2 is Germany’s Omicron.

A totally different phenomenon is occurring in the UK which has lifted all COVID restrictions, to the extent that British Airways is no longer requiring masks on airplanes. The curiously named ‘Living with COVID’ plan was implemented as a “moment of pride” on February 21st (link: https://www.cnbc.com/2022/02/21/uk-pm-boris-johnson-to-lift-all-remaining-covid-restrictions-in-england.html). In addition to rescinding mask mandates, there is no longer a requirement for individuals who test positive to self-isolate. Previously free of charge rapid antigen tests (or in UK parlance, lateral flow tests) will be phased out as well. So, in essence, a functioning test/trace/isolate policy has not just been scrapped – instead replaced with a test and no-isolate policy.

Another concerning aspect of the UK policy shift is the timing. Returning again to Figure 1 below, note that UK case rates were significantly higher than those of the US when the policy was enacted at about 40 new daily cases per 100,000 (as a reference, the case rate in Los Angeles County that week was 19.9). Unsurprisingly case rates have risen and are now at 125 new daily cases per 100,000 while Los Angeles County has continued to fall and are down to 8 new daily cases per 100,000.

Figure 1: Incidence rates of COVID-19 infection in US, UK and Germany. Mid-November 2021 through mid-March 2022.

So, in summary, the comparisons to be make with the UK or Germany experience are not strictly applicable to the US at this point in time. Germany, most certainly not, as they are just now experiencing the Omicron outbreak which consumed the US more than two months ago. They just happen to be having that experience with BA.2 rather than the original Omicron.

The US now has similarly rescinded mask mandates broadly, a move that has the potential to increase case rates. On the other hand, there has been no removal of the good public health policy to isolate for at least 5 days when one has a positive test. This well balanced article from NPR summarizes what we might expect (link: https://www.npr.org/sections/health-shots/2022/02/21/1081810074/omicron-ba2-variant-spread).  Put simply:

“A lot of us were assuming that it was going to quickly take off in the United States just like it was doing in Europe and become the new dominant variant,” says Nathan Grubaugh, an associate professor of epidemiology at the Yale School of Public Health.

So far that hasn’t happened. 

Figure 2: Incidence rates of COVID-19 infection in Los Angeles County, California. Mid-November 2021 through mid-March 2022.

 

𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿

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